Assessing pathological complete response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer: a systematic review

Clinical and genetic factors associated with tumor response to neoadjuvant (chemo)radiotherapy, survival and recurrence risk in rectal cancer

Rectal cancer poses challenges in preoperative treatment response, with up to 30% achieving a complete response (CR). Personalized treatment relies on accurate identification of responders at diagnosis. This study aimed to unravel CR determinants, overall survival (OS), and time to recurrence (TTR) using clinical and targeted sequencing data. Analyzing 402 patients undergoing preoperative treatment, tumor stage, size, and treatment emerged as robust response predictors. CR rates were higher in smaller, early-stage, and intensively treated tumors. Targeted sequencing analyzed 216 cases, while 120 patients provided hotspot mutation data. KRAS mutation dramatically reduced CR odds by over 50% (odds ratio [OR] = 0.3 in the targeted sequencing and OR = 0.4 hotspot cohorts, respectively). In contrast, SMAD4 and SYNE1 mutations were associated with higher CR rates (OR = 6.0 and 6.8, respectively). Favorable OS was linked to younger age, CR, and low baseline carcinoembryonic antigen levels. Notably, CR and an APC mutation increased TTR, while a BRAF mutation negatively affected TTR. Beyond tumor burden, SMAD4 and SYNE1 mutations significantly influenced CR. KRAS mutations independently correlated with radiotherapy resistance, and BRAF mutations heightened recurrence risk. Intriguingly, non-responding tumors with initially small sizes carried a higher risk of recurrence. The findings, even if limited in addition to the imperfect clinical factors, offer insights into rectal cancer treatment response, guiding personalized therapeutic strategies. By uncovering factors impacting CR, OS, and TTR, this study underscores the importance of tailored approaches for rectal cancer patients. These findings, based on extensive analysis and mutation data, pave the way for personalized interventions, optimizing outcomes in the challenges of rectal cancer preoperative treatment.

Does complete pathological response increase perioperative morbidity risk in rectal cancer?

AIM

The optimal management of patients with clinical complete response after neoadjuvant treatment for rectal cancer is controversial. The aim of this study is to compare the morbidity between patients with locally advanced rectal cancer who have had a pathological complete response (pCR) or not after neoadjuvant chemoradiotherapy (NCRT) and total mesorectal excision (TME). The study hypothesis was that pCR may impact the surgical complication rate.

METHOD

A retrospective cohort study was conducted of a prospectively maintained database in Australia and New Zealand, the Binational Colorectal Cancer Audit, that identified patients with locally advanced rectal cancer (<15 cm from anal verge) from 1 January 2007 to 31 December 2019. Patients were included if they had locally advanced rectal cancer and had undergone NCRT and proceeded to surgical resection.

RESULTS

There were 4584 patients who satisfied the inclusion criteria, 65% being male. The mean age was 63 years and 11% had a pCR (ypT0N0). TME with anastomosis was performed in 67.8% of patients, and the majority of the cohort received long-course radiotherapy (81.7%). Both major and minor complications were higher in the TME without anastomosis group (17.3% vs. 14.7% and 30.6% vs. 20.8%, respectively), and the 30-day mortality was 1.31%. In the TME with anastomosis group, pCR did not contribute to higher rates of surgical complications, but male gender (p < 0.0012), age (p < 0.0001), preoperative N stage (p = 0.0092) and American Society of Anesthesologists (ASA) score ≥3 (p < 0.0002) did. In addition, pCR had no significant effect (p = 0.44) but male gender (p = 0.0047) and interval to surgery (p = 0.015) contributed to higher rates of anastomotic leak. In the TME without anastomosis cohort, the only variable that contributed to higher rates of complications was ASA score ≥3 (p = 0.033).

CONCLUSION

Patients undergoing TME dissection for rectal cancer following NCRT showed no difference in complications whether they had achieved pCR or not.

Characteristics of pathologic complete response for locally advanced rectal cancer

BACKGROUND

Neoadjuvant chemoradiation (NACRT) is the standard of care for locally advanced rectal cancers. The purpose of this study was to determine patient and tumor factors associated with a pathologic complete response (pCR).

METHODS

The National Surgical Quality Improvement Program proctectomy-targeted database was utilized to identify all patients from 2016 to 2020 who underwent NACRT followed by proctectomy with curative intent for T3-4N0-2 rectal cancers.

RESULTS

A total of 1891 patients were included, of which 253 (13.4%) demonstrated a pCR. Pretreatment N0 staging was associated with a higher rate of pCR (18.9%) when compared to N1 (6.7%) and N2 (6.7%) (p < 0.0001). Patients clinically staged at T3N0 had the highest rate of pCR (19.5%). Gender, age, race, weight, smoking status, and tumor height were not associated with pCR.

CONCLUSIONS

Patients with cN0 disease were more likely to experience a pCR compared to cN1-2 patients. Tumor height relative to anal verge or patient demographics were not associated with pCR.

MRI Tumor Regression Grade Combined with T2-Weighted Volumetry May Predict Histopathological Response in Locally Advanced Rectal Cancer following Neoadjuvant Chemoradiotherapy-A New Scoring System Proposal

Modern studies focus on the discovery of innovative methods to improve the value of post-treatment magnetic resonance imaging (MRI) in the prediction of pathological responses to preoperative neoadjuvant chemoradiotherapy (nCRT) in locally advanced rectal cancer (LARC). The aim of this study was to assess the potential benefits of combining magnetic resonance tumor regression grade (mrTRG) with T2-weighted volumetry in the prediction of pathological responses to nCRT in LARC. This was a cohort study conducted on patients with histopathologically confirmed LARC in a period from 2020 to 2022. After histopathological verification, all patients underwent initial MRI studies, while the follow-up MRI was performed after nCRT. Tumor characteristics, MRI estimated tumor regression grade (mrTRG) and tumor volumetry were evaluated both initially and at follow-up. All patients were classified into responders and non-responders according to pathological tumor regression grade (pTRG) and mrTRG. A total of 71 patients, mostly male (66.2%) were included in the study. The median tumor volume reduction rate was significantly higher in nCRT-responders compared to non-responders (79.9% vs. 63.3%) (p = 0.003). Based on ROC analysis, optimal cut-off value for tumor volume reduction rate was determined with an area under the curve (AUC) value of 0.724 (p = 0.003). Using the tumor volume reduction rate ≥75% with the addition of response to nCRT according to mrTRG, a new scoring system for prediction of pTRG to preoperative nCRT in LARC was developed. Diagnostic performance of prediction score was tested and the sensitivity, PPV, specificity, and NPV were 81.8%, 56.3%, 71.4%, and 89.7%, respectively. The combination of mrTRG and T2-weighted volumetry increases the MRI-based prediction of pTRG to preoperative nCRT in LARC. The proposed scoring system could aid in distinguishing responders to nCRT, as these patients could benefit from organ-preserving treatment and a "watch and wait" strategy.

Endoscopic ultrasound-guided injection of carbon nanoparticles suspension to label rectal cancer before neoadjuvant chemoradiotherapy: a retrospective cohort study

Background

Localization of the primary tumor and ensuring safe distal surgical margins (DSMs) following neoadjuvant chemoradiotherapy (nCRT) are challenging in locally advanced rectal cancers (LARCs). This study investigated the effectiveness of carbon nanoparticles suspension (CNS) for labeling the primary tumor and allowing precise tumor resection after nCRT.

Methods

Clinicopathological data of LARC patients who underwent nCRT followed by laparoscopic radical anal preservation surgery at our center between January 2018 and February 2023 were prospectively collected. The patients were divided into the CNS tattooed (CNS) and non-tattooed (control) groups. In the CNS group, CNS was injected in four quadrants on the anal side 1 cm away from the lower tumor margin. DSMs were determined through intraoperative distal rectal examination in the control group and observation of CNS tattoos in the CNS group. DSM lengths and positive DSM rates were compared between the two groups to analyse the feasibility and effectiveness of CNS for labeling LARCs before nCRT.

Results

There was no statistically significant difference in the basic demographic data, effectiveness of nCRT, or post-operative recovery rates between the two groups (all P > 0.05). In the CNS group, CNS tattoos were observed on the outside of the rectal wall, with an overall efficiency of 87.1% (27/31). The CNS group had fewer positive DSMs and safer DSM lengths (2.73 ± 0.88 vs 2.12 ± 1.15 cm, P = 0.012) than the control group (P < 0.05).

Conclusions

Endoscopic ultrasound-guided injection of CNS tattoos before nCRT could effectively label the LARCs, ensuring safe DSMs during anus-preserving surgeries (Chictr.org.cn No.: ChiCTR2300068991).

Predicting response to chemoradiotherapy in rectal cancer via visual morphologic assessment and staging on baseline MRI: a multicenter and multireader study

PURPOSE

Pre-treatment knowledge of the anticipated response of rectal tumors to neoadjuvant chemoradiotherapy (CRT) could help to further optimize the treatment. Van Griethuysen et al. proposed a visual 5-point confidence score to predict the likelihood of response on baseline MRI. Aim was to evaluate this score in a multicenter and multireader study setting and compare it to two simplified (4-point and 2-point) adaptations in terms of diagnostic performance, interobserver agreement (IOA), and reader preference.

METHODS

Twenty-two radiologists from 14 countries (5 MRI-experts,17 general/abdominal radiologists) retrospectively reviewed 90 baseline MRIs to estimate if patients would likely achieve a (near-)complete response (nCR); first using the 5-point score by van Griethuysen (1=highly unlikely to 5=highly likely to achieve nCR), second using a 4-point adaptation (with 1-point each for high-risk T-stage, obvious mesorectal fascia invasion, nodal involvement, and extramural vascular invasion), and third using a 2-point score (unlikely/likely to achieve nCR). Diagnostic performance was calculated using ROC curves and IOA using Krippendorf's alpha (α).

RESULTS

Areas under the ROC curve to predict the likelihood of a nCR were similar for the three methods (0.71-0.74). IOA was higher for the 5- and 4-point scores (α=0.55 and 0.57 versus 0.46 for the 2-point score) with best results for the MRI-experts (α=0.64-0.65). Most readers (55%) favored the 4-point score.

CONCLUSIONS

Visual morphologic assessment and staging methods can predict neoadjuvant treatment response with moderate-good performance. Compared to a previously published confidence-based scoring system, study readers preferred a simplified 4-point risk score based on high-risk T-stage, MRF involvement, nodal involvement, and EMVI.

The Role of Probe-Based Confocal Laser Endomicroscopy (pCLE) in the Diagnosis of Sustained Clinical Complete Response Under Watch-and-Wait Strategy After Neoadjuvant Chemoradiotherapy for Locally Advanced Rectal Adenocarcinoma: a Score Validation

BACKGROUND

Watch-and-wait strategy has been increasingly accepted for patients with clinical complete response (cCR) after multimodal treatment for locally advanced rectal adenocarcinoma. Close follow-up is essential to the early detection of local regrowth. It was previously demonstrated that probe-based confocal laser endomicroscopy (pCLE) scoring using the combination of epithelial and vascular features might improve the diagnostic accuracy of cCR.

AIM

To validate the pCLE scoring system in the assessment of patients with cCR after neoadjuvant chemoradiotherapy (nCRxt) for advanced rectal adenocarcinoma.

METHODS

Digital rectal examination, pelvic magnetic resonance imaging (MRI), and pCLE were performed in 43 patients with cCR, who presented either a scar (N = 33; 76.7%) or a small ulcer with no signs of tumor, and/or biopsy negative for malignancy (N = 10; 23.3%).

RESULTS

Twenty-five (58.1%) patients were men, and the mean age was 58.4 years. During the follow-up, 12/43 (27.9%) patients presented local regrowth and underwent salvage surgery. There was an association between pCLE diagnostic scoring and final histological report (for patients who underwent surgical resection) or final diagnosis at the latest follow-up (p = 0.0001), while this association was not observed with MRI (p = 0.49). pCLE sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 66.7%, 93.5%, 80%, 88.9%, and 86%, respectively. MRI sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 66.7%, 48.4%, 66.7%, 78.9%, and 53.5%, respectively.

CONCLUSIONS

pCLE scoring system based on epithelial and vascular features improved the diagnosis of sustained cCR and might be recommended during follow-up. pCLE might add some valuable contribution for identifying local regrowth. Trial Registration This protocol was registered at the Clinical Trials (ClinicalTrials.gov identifier NCT02284802).

Treatment stratification and prognosis assessment using circulating tumor DNA in locally advanced rectal cancer: A systematic review and meta-analysis

BACKGROUND

Circulating tumor DNA (ctDNA) is an emerging biomarker for locally advanced rectal cancer (LARC), giving hope for stratified treatment. As the completed studies have small sample sizes and different experimental methods, systematic review and meta-analysis were performed to explore their role in predicting pathological complete response (pCR), tumor recurrence, and prognosis.

METHODS

PubMed, Embase, and the Web of Science were searched for potentially eligible studies published up to September 6, 2022. Pooled relative risk (RR) was calculated to predict pCR and tumor recurrence, and pooled hazard ratio (HR) was calculated to evaluate the prognosis of overall survival (OS), recurrence-free survival (RFS), and metastasis-free survival (MRS).

RESULTS

Twelve studies published between 2018 and 2022 included 931 patients, and 2544 serum samples were eventually included in the meta-analysis. The pooled revealed that ctDNA-negative patients were more likely to have a pCR (RR = 1.64, 95% confidence interval [CI]: 1.26-2.12). The pooled revealed that ctDNA-positive patients were at high risk of recurrence (RR = 3.37, 95% CI: 2.34-4.85) and had a poorer prognosis for OS (HR = 3.03, 95% CI: 1.86-4.95), RFS (HR = 7.08, 95% CI: 4.12-12.14), and MRS (HR = 2.77, 95% CI: 2.01-3.83).

CONCLUSION

ctDNA may be useful for stratifying treatment and assessing prognosis in patients with LARC, but its clinical application still needs to be confirmed in a prospective multicenter study with large samples.

Minimal residual disease in solid tumors: an overview

Minimal residual disease (MRD) is termed as the small numbers of remnant tumor cells in a subset of patients with tumors. Liquid biopsy is increasingly used for the detection of MRD, illustrating the potential of MRD detection to provide more accurate management for cancer patients. As new techniques and algorithms have enhanced the performance of MRD detection, the approach is becoming more widely and routinely used to predict the prognosis and monitor the relapse of cancer patients. In fact, MRD detection has been shown to achieve better performance than imaging methods. On this basis, rigorous investigation of MRD detection as an integral method for guiding clinical treatment has made important advances. This review summarizes the development of MRD biomarkers, techniques, and strategies for the detection of cancer, and emphasizes the application of MRD detection in solid tumors, particularly for the guidance of clinical treatment.

MRI for nodal restaging after neoadjuvant therapy in rectal cancer with histopathologic comparison

BACKGROUND

After neoadjuvant therapy, most of the lymph nodes (LNs) will shrink and disappear in patients with rectal cancer. However, LNs that are still detectable on MRI carry a risk of metastasis. This study aimed to evaluate the performance of the European Society of Gastrointestinal and Abdominal Radiology (ESGAR) criterion (short-axis diameter ≥ 5 mm) in diagnosing malignant LNs in patients with rectal cancer after neoadjuvant therapy, and whether nodal morphological characteristics (including shape, border, signal homogeneity, and enhancement homogeneity) could improve the diagnostic efficiency for LNs ≥ 5 mm.

METHODS

This retrospective study included 90 patients with locally advanced rectal cancer who underwent surgery after neoadjuvant therapy and performed preoperative MRI. Two radiologists independently measured the short-axis diameter of LNs and evaluated the morphological characteristics of LNs ≥ 5 mm in consensus. With a per node comparison with histopathology as the reference standard, a ROC curve was performed to evaluate the diagnostic performance of the size criterion. For categorical variables, either a χ² test or Fisher's exact test was used.

RESULTS

A total of 298 LNs were evaluated. The AUC for nodal size in determining nodal status was 0.81. With a size cutoff value of 5 mm, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 65.9%, 87.0%, 46.8%, 93.6% and 83.9%, respectively. No significant differences were observed in any of the morphological characteristics between benign and malignant LNs ≥ 5 mm (all P > 0.05).

CONCLUSIONS

The ESGAR criterion demonstrated moderate diagnostic performance in identifying malignant LNs in patients with rectal cancer after neoadjuvant therapy. It was effective in determining the status of LNs < 5 mm but not for LNs ≥ 5 mm, and the diagnostic efficiency could not be improved by considering nodal morphological characteristics.

Emerging Roles of Circulating Tumor DNA for Increased Precision and Personalization in Radiation Oncology

Recent breakthroughs in circulating tumor DNA (ctDNA) technologies present a compelling opportunity to combine this emerging liquid biopsy approach with the field of radiogenomics, the study of how tumor genomics correlate with radiotherapy response and radiotoxicity. Canonically, ctDNA levels reflect metastatic tumor burden, although newer ultrasensitive technologies can be used after curative-intent radiotherapy of localized disease to assess ctDNA for minimal residual disease (MRD) detection or for post-treatment surveillance. Furthermore, several studies have demonstrated the potential utility of ctDNA analysis across various cancer types managed with radiotherapy or chemoradiotherapy, including sarcoma and cancers of the head and neck, lung, colon, rectum, bladder, and prostate . Additionally, because peripheral blood mononuclear cells are routinely collected alongside ctDNA to filter out mutations associated with clonal hematopoiesis, these cells are also available for single nucleotide polymorphism analysis and could potentially be used to detect patients at high risk for radiotoxicity. Lastly, future ctDNA assays will be utilized to better assess locoregional MRD in order to more precisely guide adjuvant radiotherapy after surgery in cases of localized disease, and guide ablative radiotherapy in cases of oligometastatic disease.

Predictive value of modified MRI-based split scar sign (mrSSS) score for pathological complete response after neoadjuvant chemoradiotherapy for patients with rectal cancer

PURPOSE

To measure the diagnostic performance of modified MRI-based split scar sign (mrSSS) score for the prediction of pathological complete response (pCR) after neoadjuvant chemoradiotherapy (nCRT) for patients with rectal cancer.

METHODS

The modified MRI-based split scar sign (mrSSS) score, which consists of T2-weighted images (T2WI)-based score and diffusion-weighted images (DWI)-based score. The sensitivity, specificity, and accuracy of modified mrSSS score, endoscopic gross type, and MRI-based tumor regression grading (mrTRG) score, in the prediction of pCR, were compared. The prognostic value of the modified mrSSS score was also studied.

RESULTS

A total of 189 patients were included in the study. The Kendall's coefficient of interobserver concordance of modified mrSSS score, T2WI -based score, and DWI-based score were 0.899, 0.890, and 0.789 respectively. And the maximum and minimum k value of the modified mrSSS score was 0.797 (0.742-0.853) and 0.562 (0.490-0.634). The sensitivity, specificity, and accuracy of prediction of pCR were 0.66, 0.97, and 0.90 for modified mrSSS score; 0.37, 0.89, and 0.78 for endoscopic gross type (scar); and 0.24, 0.92, and 0.77 for mrTRG score (mrTRG = 1). The modified mrSSS score had significantly higher sensitivity than the endoscopic gross type and the mrTRG score in predicting pCR. Patients with lower modified mrSSS scores had significantly longer disease-free survival (P < 0.05).

CONCLUSION

The modified mrSSS score showed satisfactory interobserver agreement and higher sensitivity in predicting pCR after nCRT in patients with rectal cancer. The modified mrSSS score is also a predictor of disease-free survival.

Utility of Circulating Free DNA Fragmentomics in the Prediction of Pathological Response after Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer

BACKGROUND

A "Watch and Wait" (W&W) approach has become an alternative to surgery for locally advanced rectal cancer (LARC) after neoadjuvant chemoradiotherapy (nCRT). Precise prediction of pathological complete response (pCR) will improve patient selection for W&W. We investigated the utility of cell-free DNA (cfDNA) fragmentomics in predicting pCR.

METHODS

We recruited 119 LARC patients and evaluated nCRT response by pCR status and pathological or MRI tumor regression grade (mrTRG). Plasma samples before, during, and after nCRT were applied to deep targeted-panel sequencing, with 103 patients having complete samples. cfDNA fragment and 5'-end motif profiles were used to construct elastic-net logistic regression models to predict non-pCR. Predictive performance was measured by area under the receiver operator characteristic curve (AUC), sensitivity, and specificity.

RESULTS

In the training cohort, the model based on 5'-end motif profile plus mrTRG achieved the highest cross-validation AUC (0.92, 95% CI, 0.91-0.93). The AUC in a testing cohort was 0.96 (95% CI, 0.90-1.00). The models based on 5'-end motif profile alone or in combination with mrTRG both maintained good predictive ability for patients without detectable circulating tumor DNA (AUC 0.94, 95% CI, 0.93-0.95; AUC 0.95, 95% CI, 0.94-0.96). In an external validation cohort, the model trained with a local 5'-end motif profile obtained an AUC of 0.878 (95% CI, 0.801-0.956) in discriminating colorectal cancer from healthy subjects.

CONCLUSIONS

The combination of a 5'-end motif profile with mrTRG has the potential to predict the response to nCRT, and therefore may improve the patient selection for a W&W approach.

Impact of Prediagnosis Risk of Major Depressive Disorder and Health-Related Quality of Life on Treatment Choice for Stage II-III Rectal Cancer

PURPOSE

We hypothesized that depressive symptoms and health-related quality of life (HRQOL) reported by patients before their cancer diagnoses would be associated with treatment choice for stage II and III rectal cancer, specifically whether patients underwent surgery.

METHODS

The Surveillance, Epidemiology, and End Results and Medicare Health Outcomes Survey linked data set was used to identify patients with stage II-III rectal adenocarcinoma diagnosed between 2004 and 2013 who had completed the health outcomes survey within 36 months before their cancer diagnoses. Risk for major depressive disorder (MDD) was determined on the basis of responses to screening questions for depressive disorders. HRQOL was assessed using the Mental Component Summary and Physical Component Summary of the 36-Item Short Form Survey and Veterans RAND 12-Item Health Survey. Using univariable and multivariable analyses, we assessed for associations between health survey responses and ultimate treatment modality.

RESULTS

We identified 142 evaluable patients, of whom 109 (76.8%) underwent surgery. Thirty patients (21.1%) met criteria for being at risk for MDD before their cancer diagnoses. Patients at risk for MDD underwent surgery less often than those not at risk (P = .0499), and this association strengthened after adjusting for patient characteristics (odds ratio, 0.17; 95% CI, 0.04 to 0.82; P = .027). There was a nonsignificant trend between higher Mental Component Summary scores (indicating higher self-reported mental HRQOL) and increased frequency of undergoing surgery (P = .081). There were no significant associations between the Physical Component Summary and treatment modality.

CONCLUSION

In Medicare beneficiaries with stage II-III rectal cancer, those at risk for MDD underwent standard-of-care treatment with surgery less frequently. Further studies are warranted to assess the effect of mental health on clinical decision making in this patient population.

Exploring biomarkers for prognosis and neoadjuvant chemosensitivity in rectal cancer: Multi-omics and ctDNA sequencing collaboration

Introduction

This study aimed to identified the key genes and sequencing metrics for predicting prognosis and efficacy of neoadjuvant chemotherapy (nCT) in rectal cancer (RC) based on genomic DNA sequencing in samples with different origin and multi-omics association database.

Methods

We collected 16 RC patients and obtained DNA sequencing data from cancer tissues and plasma cell-free DNA before and after nCT. Various gene variations were analyzed, including single nucleotide variants (SNV), copy number variation (CNV), tumor mutation burden (TMB), copy number instability (CNI) and mutant-allele tumor heterogeneity (MATH). We also identified genes by which CNV level can differentiate the response to nCT. The Cancer Genome Atlas database and the Clinical Proteomic Tumor Analysis Consortium database were used to further evaluate the specific role of therapeutic relevant genes and screen out the key genes in multi-omics levels. After the intersection of the screened genes from differential expression analysis, survival analysis and principal components analysis dimensionality reduction cluster analysis, the key genes were finally identified.

Results

The genes CNV level of principal component genes in baseline blood and cancer tissues could significantly distinguish the two groups of patients. The CNV of HSP90AA1, EGFR, SRC, MTOR, etc. were relatively gained in the better group compared with the poor group in baseline blood. The CNI and TMB was significantly different between the two groups. The increased expression of HSP90AA1, EGFR, and SRC was associated with increased sensitivity to multiple chemotherapeutic drugs. The nCT predictive score obtained by therapeutic relevant genes could be a potential prognostic indicator, and the combination with TMB could further refine prognostic prediction for patients. After a series of analysis in multi-omics association database, EGFR and HSP90AA1 with significant differences in multiple aspects were identified as the key predictive genes related to prognosis and the sensitivity of nCT.

Discussion

This work revealed that effective combined application and analysis in multi-omics data are critical to search for predictive biomarkers. The key genes EGFR and HSP90AA1 could serve as an effective biomarker to predict prognose and neoadjuvant chemosensitivity.

Extracellular volume fraction determined by equilibrium contrast-enhanced CT for the prediction of the pathological complete response to neoadjuvant chemoradiotherapy for locally advanced rectal cancer

OBJECTIVES

To determine the extracellular volume (ECV) fraction derived from equilibrium contrast-enhanced CT for predicting pathological complete response (pCR) after neoadjuvant chemoradiotherapy (NCRT) in locally advanced rectal cancer (LARC).

METHODS

The ECV fraction before NCRT (ECV_pre) and/or ECV after NCRT (ECV_post) of rectal tumors was assessed, and ECV_Δ was calculated as ECV_post - ECV_pre. The histopathologic tumor regression grading (TRG) was assessed. pCR (TRG 0 grade) was defined as the absence of viable tumor cells in the primary tumor and lymph nodes. Demographic and clinicopathological characteristics and ECV fraction were compared between the pCR and non-pCR groups. A mixed model was constructed by logistic regression. The performance for predicting pCR was assessed with the area under the receiver-operator curve (AUC). The AUCs of the different methods were compared by the method proposed by DeLong et al. RESULTS: Seventy-five patients were included; 17 achieved pCR, and 58 achieved non-pCR. The ECV_post (17.05 ± 2.36% vs. 29.94 ± 1.20%; p < 0.001) and ECV_Δ (- 17.01 ± 3.01% vs. 0.44 ± 1.45%; p < 0.001) values in the pCR group were significantly lower than those in the non-pCR group. The mixed model that combined ECV_post with ECV_Δ achieved an AUC of 0.92 (95% confidence interval (CI) = 0.81-0.98), which was higher than that of ECV_post (AUC, 0.91 (95% CI = 0.80-0.97); p = 0.60) or ECV_Δ (AUC, 0.90 (95% CI = 0.79-0.97); p = 0.61).

CONCLUSIONS

ECV_post and ECV_Δ determined by using equilibrium contrast-enhanced CT were useful in distinguishing between pCR and non-pCR patients with LARC who received NCRT.

KEY POINTS

• ECV_post and ECV_Δ (ECV_post - ECV_pre) differed significantly between the non-pCR and pCR groups. • ECV_pre cannot be used to predict the efficacy of neoadjuvant chemoradiotherapy. • ECV_post combined with ECV_Δ had the best performance with an AUC of 0.92 for predicting pCR after NCRT in LARC.

Changes of serum metabolites levels during neoadjuvant chemoradiation and prediction of the pathological response in locally advanced rectal cancer

INTRODUCTION

Previous studies have explored prediction value of serum metabolites in neoadjuvant chemoradiation therapy (NCRT) response for rectal cancer. To date, limited literature is available for serum metabolome changes dynamically through NCRT.

OBJECTIVES

This study aimed to explore temporal change pattern of serum metabolites during NCRT, and potential metabolic biomarkers to predict the pathological response to NCRT in locally advanced rectal cancer (LARC) patients.

METHODS

Based on dynamic UHPLC-QTOF-MS untargeted metabolomics design, this study included 106 LARC patients treated with NCRT. Biological samples of the enrolled patients were collected in five consecutive time-points. Untargeted metabolomics was used to profile serum metabolic signatures from LARC patients. Then, we used fuzzy C-means clustering (FCM) to explore temporal change patterns in metabolites cluster and identify monotonously changing metabolites during NCRT. Repeated measure analysis of variance (RM-ANOVA) and multilevel partial least-squares discriminant analysis (ML-PLS-DA) were performed to select metabolic biomarkers. Finally, a panel of dynamic differential metabolites was used to build logistic regression prediction models.

RESULTS

Metabolite profiles showed a clearly tendency of separation between different follow-up panels. We identified two clusters of 155 serum metabolites with monotonously changing patterns during NCRT (74 decreased metabolites and 81 increased metabolites). Using RM-ANOVA and ML-PLS-DA, 8 metabolites (L-Norleucine, Betaine, Hypoxanthine, Acetylcholine, 1-Hexadecanoyl-sn-glycero-3-phosphocholine, Glycerophosphocholine, Alpha-ketoisovaleric acid, N-Acetyl-L-alanine) were further identified as dynamic differential biomarkers for predicting NCRT sensitivity. The area under the ROC curve (AUC) of prediction model combined with the baseline measurement was 0.54 (95%CI = 0.43 ~ 0.65). By incorporating the variability indexes of 8 dynamic differential metabolites, the prediction model showed better discrimination performance than baseline measurement, with AUC = 0.67 (95%CI 0.57 ~ 0.77), 0.64 (0.53 ~ 0.75), 0.60 (0.50 ~ 0.71), and 0.56 (0.45 ~ 0.67) for the variability index of difference, linear slope, ratio, and standard deviation, respectively.

CONCLUSION

This study identified eight metabolites as dynamic differential biomarkers to discriminate NCRT-sensitive and resistant patients. The changes of metabolite level during NCRT show better performance in predicting NCRT sensitivity. These findings highlight the clinical significance of metabolites variabilities in metabolomics analysis.

Application of Radiomics in Predicting Treatment Response to Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer: Strategies and Challenges

Neoadjuvant chemoradiotherapy (nCRT) followed by total mesorectal excision is the standard treatment for locally advanced rectal cancer (LARC). A noninvasive preoperative prediction method should greatly assist in the evaluation of response to nCRT and for the development of a personalized strategy for patients with LARC. Assessment of nCRT relies on imaging and radiomics can extract valuable quantitative data from medical images. In this review, we examined the status of radiomic application for assessing response to nCRT in patients with LARC and indicated a potential direction for future research.

CT radiomics identifying non-responders to neoadjuvant chemoradiotherapy among patients with locally advanced rectal cancer

BACKGROUND AND PURPOSE

Early detection of non-response to neoadjuvant chemoradiotherapy (nCRT) for locally advanced colorectal cancer (LARC) remains challenging. We aimed to assess whether pretreatment radiotherapy planning computed tomography (CT) radiomics could distinguish the patients with no response or no downstaging after nCRT from those with response and downstaging after nCRT.

MATERIALS AND METHODS

Patients with LARC who were treated with nCRT were retrospectively enrolled between March 2009 and March 2019. Traditional radiological characteristics were analyzed by visual inspection and radiomic features were analyzed through computational methods from the pretreatment radiotherapy planning CT images. Differentiation models were constructed using radiomic methods and clinicopathological characteristics for predicting non-response to nCRT. Model performance was assessed for classification efficiency, calibration, discrimination, and clinical application.

RESULTS

This study enrolled a total of 215 patients, including 151 patients in the training cohort (50 non-responders and 101 responders) and 64 patients in the validation cohort (21 non-responders and 43 responders). For predicting non-response, the model constructed with an ensemble machine learning method had higher performance with area under the curve (AUC) values of 0.92 and 0.89 as compared to the model constructed with the logistic regression method (AUC: 0.72 and 0.71 for the training and validation cohorts, respectively). Both decision curve and calibration curve analyses confirmed that the ensemble machine learning model had higher prediction performance.

CONCLUSION

Pretreatment CT radiomics achieved satisfying performance in predicting non-response to nCRT and could be helpful to assist in treatment planning for patients with LARC.

Contemporary Management of Locally Advanced and Recurrent Rectal Cancer: Views from the PelvEx Collaborative

Pelvic exenteration is a complex operation performed for locally advanced and recurrent pelvic cancers. The goal of surgery is to achieve clear margins, therefore identifying adjacent or involved organs, bone, muscle, nerves and/or vascular structures that may need resection. While these extensive resections are potentially curative, they can be associated with substantial morbidity. Recently, there has been a move to centralize care to specialized units, as this facilitates better multidisciplinary care input. Advancements in pelvic oncology and surgical innovation have redefined the boundaries of pelvic exenterative surgery. Combined with improved neoadjuvant therapies, advances in diagnostics, and better reconstructive techniques have provided quicker recovery and better quality of life outcomes, with improved survival This article provides highlights of the current management of advanced pelvic cancers in terms of surgical strategy and potential future developments.

Prognostic Impact of An Integrative Landscape of Clinical, Immune, and Molecular Features in Non-Metastatic Rectal Cancer

Rectal Cancer (RC) is a complex disease that involves highly variable treatment responses. Currently, there is a lack of reliable markers beyond TNM to deliver a personalized treatment in a cancer setting where the goal is a curative treatment. Here, we performed an integrated characterization of the predictive and prognostic role of clinical features, mismatch-repair deficiency markers, HER2, CDX2, PD-L1 expression, and CD3-CD8+ tumor-infiltrating lymphocytes (TILs) coupled with targeted DNA sequencing of 76 non-metastatic RC patients assigned to total mesorectal excision upfront (TME; n = 15) or neoadjuvant chemo-radiotherapy treatment (nCRT; n = 61) followed by TME. Eighty-two percent of RC cases displayed mutations affecting cancer driver genes such as TP53, APC, KRAS, ATM, and PIK3CA. Good response to nCRT treatment was observed in approximately 40% of the RC cases, and poor pathological tumor regression was significantly associated with worse disease-free survival (DFS, HR = 3.45; 95%CI = 1.14-10.4; p = 0.028). High neutrophils-platelets score (NPS) (OR = 10.52; 95%CI=1.34-82.6; p = 0.025) and KRAS mutated cases (OR = 5.49; 95%CI = 1.06-28.4; p = 0.042) were identified as independent predictive factors of poor response to nCRT treatment in a multivariate analysis. Furthermore, a Cox proportional-hazard model showed that the KRAS mutational status was an independent prognostic factor associated with higher risk of local recurrence (HR = 9.68; 95%CI = 1.01-93.2; p <0.05) and shorter DFS (HR = 2.55; 95%CI = 1.05-6.21; p <0.05), while high CEA serum levels were associated with poor DFS (HR = 2.63; 95%CI = 1.01-6.85; p <0.05). Integrated clinical and molecular-based unsupervised analysis allowed us to identify two RC prognostic groups (cluster 1 and cluster 2) associated with disease-specific OS (HR = 20.64; 95%CI = 2.63-162.2; p <0.0001), metastasis-free survival (HR = 3.67; 95%CI = 1.22-11; p = 0.012), local recurrence-free survival (HR = 3.34; 95%CI = 0.96-11.6; p = 0.043) and worse DFS (HR = 2.68; 95%CI = 1.18-6.06; p = 0.012). The worst prognosis cluster 2 was enriched by stage III high-risk clinical tumors, poor responders to nCRT, with low TILs density and high frequency of KRAS and TP53 mutated cases compared with the best prognosis cluster 1 (p <0.05). Overall, this study provides a comprehensive and integrated characterization of non-metastatic RC cases as a new insight to deliver a personalized therapeutic approach.

Evaluation and Predictive Factors of Complete Response in Rectal Cancer after Neoadjuvant Chemoradiation Therapy

The response to neoadjuvant chemoradiation therapy is an important prognostic factor for locally advanced rectal cancer. Although the majority of the patients after neoadjuvant therapy are referred to following surgery, the clinical data show that complete clinical or pathological response is found in a significant proportion of the patients. Diagnostic accuracy of confirming the complete response has a crucial role in further management of a rectal cancer patient. As the rate of clinical complete response, unfortunately, is not always consistent with pathological complete response, accurate diagnostic parameters and predictive markers of tumor response may help to guide more personalized treatment strategies and identify potential candidates for nonoperative management more safely. The management of complete response demands interdisciplinary collaboration including oncologists, radiotherapists, radiologists, pathologists, endoscopists and surgeons, because the absence of a multidisciplinary approach may compromise the oncological outcome. Prediction and improvement of rectal cancer response to neoadjuvant therapy is still an active and challenging field of further research. This literature review is summarizing the main, currently known clinical information about the complete response that could be useful in case if encountering such condition in rectal cancer patients after neoadjuvant chemoradiation therapy, using as a source PubMed publications from 2010–2021 matching the search terms “rectal cancer”, “neoadjuvant therapy” and “response”.

Histopathological, Radiological, and Demographic Factors Predicting the Response to Neoadjuvant Therapy for Rectal Cancer

BACKGROUND/AIM

While the treatment for early stage rectal cancer is surgery, when a diagnosis is made at a locally advanced stage, it is recommended to start treatment with neoadjuvant chemoradiotherapy. Therefore, it is important to determine which patients will respond best to neoadjuvant treatment. The aim of this study was to investigate which hematological, histopathological, and radiological parameters can predict the response to chemoradiotherapy.

METHODS AND MATERIAL

A retrospective examination was made of 43 patients who underwent surgery following neoadjuvant chemoradiotherapy because of locally advanced stage rectal cancer. Demographic data were collected from the patient files, and the radiological, histopathological, and laboratory findings before neoadjuvant chemoradiotherapy were compared with the findings after treatment.

RESULTS

In the postoperative evaluation, a pathological complete response was determined in 25.50% of the patients. Lymphovascular invasion, perineural invasion, and absence of necrosisis were seen to be statistically related to major response (p < 0.05), and in patients where the tumor was closer than 6 cm to the anal verge, the response was better CONCLUSION: When the findings were examined, histopathological lymphovascular invasion, perineural invasion, the presence of necrosis, and the anal verge distance were evaluated as parameters predicting the response to neoadjuvant chemoradiotherapy in rectal cancer.

The predictive value of PET/CT for distant recurrences in locally advanced rectal cancer treated with neoadjuvant chemoradiotherapy

INTRODUCTION

It is well recognized that pathological complete response (pCR) for locally advanced rectal cancer after neoadjuvant chemoradiotherapy (CRT) confers a positive survival advantage. Despite this, a small proportion of patients can develop distant recurrence, and these are the patients that will likely benefit from adjuvant therapy. This study aims to investigate the role of PET/CT as a functional imaging to stratify patients according to their risk of distant recurrence.

METHODS

This is a retrospective analysis of a prospectively maintained database in a single quaternary teaching hospital from 2010 to 2019. All consecutive cases of locally advanced rectal cancer with restaging PET/CT were included. The primary outcome measure was 5-year OS and distant recurrence-free survival.

RESULTS

A pCR and complete metabolic response (CMR) were identified in 47 (18%) patients and 73 (27.4%) patients respectively. Of these, 26 patients had both pCR and CMR and these patients remained free of local and distant recurrence at their last censored date. Patients with both pCR and CMR achieved the highest 5-year overall survival of 96.2%, followed by those with pCR and incomplete CMR (iCMR) of 85.7%, non-pCR and CMR of 85.1% and non-pCR and iCMR of 83.1%. Independent predictors for 5-year distant recurrence-free survival were pathological and PET metabolic response, nodal staging and lymphovascular invasion (LVI).

CONCLUSION

In conclusion, a PET/CT has the potential to better stratify patients of their risk of distant metastasis. However, a larger validation cohort is required before these findings can be translated to clinical utility.

Utility of ctDNA in predicting response to neoadjuvant chemoradiotherapy and prognosis assessment in locally advanced rectal cancer: A prospective cohort study

BACKGROUND

For locally advanced rectal cancer (LARC) patients who receive neoadjuvant chemoradiotherapy (nCRT), there are no reliable indicators to accurately predict pathological complete response (pCR) before surgery. For patients with clinical complete response (cCR), a "Watch and Wait" (W&W) approach can be adopted to improve quality of life. However, W&W approach may increase the recurrence risk in patients who are judged to be cCR but have minimal residual disease (MRD). Magnetic resonance imaging (MRI) is a major tool to evaluate response to nCRT; however, its ability to predict pCR needs to be improved. In this prospective cohort study, we explored the value of circulating tumor DNA (ctDNA) in combination with MRI in the prediction of pCR before surgery and investigated the utility of ctDNA in risk stratification and prognostic prediction for patients undergoing nCRT and total mesorectal excision (TME).

METHODS AND FINDINGS

We recruited 119 Chinese LARC patients (cT3-4/N0-2/M0; median age of 57; 85 males) who were treated with nCRT plus TME at Fudan University Shanghai Cancer Center (China) from February 7, 2016 to October 31, 2017. Plasma samples at baseline, during nCRT, and after surgery were collected. A total of 531 plasma samples were collected and subjected to deep targeted panel sequencing of 422 cancer-related genes. The association among ctDNA status, treatment response, and prognosis was analyzed. The performance of ctDNA alone, MRI alone, and combining ctDNA with MRI was evaluated for their ability to predict pCR/non-pCR. Ranging from complete tumor regression (pathological tumor regression grade 0; pTRG0) to poor regression (pTRG3), the ctDNA clearance rate during nCRT showed a significant decreasing trend (95.7%, 77.8%, 71.1%, and 66.7% in pTRG 0, 1, 2, and 3 groups, respectively, P = 0.008), while the detection rate of acquired mutations in ctDNA showed an increasing trend (3.8%, 8.3%, 19.2%, and 23.1% in pTRG 0, 1, 2, and 3 groups, respectively, P = 0.02). Univariable logistic regression showed that ctDNA clearance was associated with a low probability of non-pCR (odds ratio = 0.11, 95% confidence interval [95% CI] = 0.01 to 0.6, P = 0.04). A risk score predictive model, which incorporated both ctDNA (i.e., features of baseline ctDNA, ctDNA clearance, and acquired mutation status) and MRI tumor regression grade (mrTRG), was developed and demonstrated improved performance in predicting pCR/non-pCR (area under the curve [AUC] = 0.886, 95% CI = 0.810 to 0.962) compared with models derived from only ctDNA (AUC = 0.818, 95% CI = 0.725 to 0.912) or only mrTRG (AUC = 0.729, 95% CI = 0.641 to 0.816). The detection of potential colorectal cancer (CRC) driver genes in ctDNA after nCRT indicated a significantly worse recurrence-free survival (RFS) (hazard ratio [HR] = 9.29, 95% CI = 3.74 to 23.10, P < 0.001). Patients with detectable driver mutations and positive high-risk feature (HR_feature) after surgery had the highest recurrence risk (HR = 90.29, 95% CI = 17.01 to 479.26, P < 0.001). Limitations include relatively small sample size, lack of independent external validation, no serial ctDNA testing after surgery, and a relatively short follow-up period.

CONCLUSIONS

The model combining ctDNA and MRI improved the predictive performance compared with the models derived from individual information, and combining ctDNA with HR_feature can stratify patients with a high risk of recurrence. Therefore, ctDNA can supplement MRI to better predict nCRT response, and it could potentially help patient selection for nonoperative management and guide the treatment strategy for those with different recurrence risks.

Complete Pathologic Response of Multiple Liver Metastases and Clinical Complete Response of Rectal Cancer in a Patient with Ataxia-Telangiectasia Mutated Gene Mutations After XELOXIRI Plus Bevacizumab: A Case Report

Background

Doublet or triplet chemotherapy plus or minus targeted drugs can achieve a high objective response rate (ORR) and are currently considered to be the backbone of conventional therapy for liver metastatic colorectal cancer (mCRC). However, current biomarkers (such as UGT1A1 and DPYD) are limited to the prediction of toxicity and there are no effective biomarkers to predict chemotherapy response. Therefore, personalized cancer chemotherapy underpinned by genomic alterations in mCRC has received increasing attention.

Case Presentation

We present a case of a 28-year-old female rectal cancer patient with multiple liver metastases (clinical risk score, CRS = 5 points). The patient underwent XELOXIRI plus bevacizumab regimen that consisted of irinotecan (150 mg/m2), oxaliplatin (100 mg/m2) on day 1, capecitabine (1700 mg/m2 per day from day 2 to 15), bevacizumab (7.5 mg/kg) on day 1 (on the second cycle), given every three weeks for eight cycles. After multi-disciplinary team (MDT) discussion, the patient underwent right hemihepatectomy, partial liver resection of segment IV and cholecystectomy. Surprisingly, the patient achieved a complete pathologic response (pCR) of the hepatic metastasis and clinical complete response (cCR) of the primary rectal lesion. A paired tumor molecular profile revealed somatic mutations in ataxia-telangiectasia mutated (ATM) genes that may explain why the patient achieved such a dramatic tumor response. Treatment was discontinued after eight cycles of a single oral dose of capecitabine and the patient started a follow-up program of physical and radiological examinations. To monitor the signs of recurrence, we also obtained blood samples to analyze circulating tumor DNA (ctDNA). To date, the patient has remained disease-free.

Conclusion

The XELOXIRI-bevacizumab regimen is a feasible and effective regimen for patients with mCRC. Mutations in the ATM genes may characterize a subset of patients with a better prognosis who are more sensitive to chemotherapy plus biological agents.

Early conformational changes at tumour bed and long term response after neoadjuvant therapy in locally-advanced rectal cancer

OBJECTIVES

To evaluate how changes in tumour scar depth angle and thickness in the post-neoadjuvant period relate to long-term response in locally-advanced rectal cancer patients.

METHODS

Informed consent was obtained from all patients and institutional review board approved this retrospective study. Sixty-nine consecutive locally-advanced rectal cancer patients who underwent neoadjuvant therapy and were selected for "Watch-and-Wait" were enrolled. Two radiologists, O1 and O2, blindly and independently reviewed the 1st and 2nd post-neoadjuvant therapy pelvic MRI T2-weighted images and recorded depth angle and thickness of the tumour scar. Value changes were calculated by simple subtraction (2nd-1st). Mann-Whitney U test was employed to assess for significant differences between sustained clinical complete responders (SCR), defined as patients with pathologic complete response or clinical complete response with a minimum follow-up of 1 year; and non-sustained complete responders (non-SCR). Interobserver agreement was estimated using intraclass correlation coefficient (ICC). Data on mrTRG, DWI and endoscopy at 1st and 2nd timepoints were retrieved for comparison.

RESULTS

In SCR, depth angle change between 1st (med = 10 weeks after end of radiotherapy) and 2nd (med = 23 weeks after end of radiotherapy) timepoints was significantly different (O1:p = 0.004; O2:p = 0.010): the SCR group showed a depth angle reduction (O1:med=-4.45; O2:med=-2.35), whereas non-SCRs showed a depth angle increase (O1:med=+2.60; O2:med=+7.40). Also, at 2nd timepoint, SCR scars were significantly thinner both for O1 (p = 0.003; SCR:med = 7.05 mm; non-SCR:med = 9.4 mm) and O2 (p = 0.006; SCR:med = 6.45 mm; non-SCR:med = 8.2 mm). A depth angle increase >21^º between 1st and 2nd timepoints and a scar thickness >10 mm at 2nd timepoint were not sensitive but were highly specific for a non-SCR (91/94 %) for both observers. Interobserver agreement was good for scar depth angle change (ICC = 0.65) and excellent for scar thickness at 2nd timepoint (ICC = 0.84). Of the retrieved data, only DWI at 2nd timepoint was discriminative (p = 0.043) providing a similar sensitivity (33 %) and a slightly lower specificity (87.5 %).

CONCLUSION

Tumour scar expansion >21° between 1st and 2nd post-neoadjuvancy MRI and a scar thickness >10 mm at 2nd post-neoadjuvancy MRI may consistently indicate a non-SCR with high specificity in locally-advanced rectal cancer patients.

Molecular and Dynamic Evaluation of Proteins Related to Resistance to Neoadjuvant Treatment with Chemoradiotherapy in Circulating Tumor Cells of Patients with Locally Advanced Rectal Cancer

The heterogeneity of response to neoadjuvant chemoradiotherapy (NCRT) is still a challenge in locally advanced rectal cancer (LARC). The evaluation of thymidylate synthase (TYMS) and RAD23 homolog B (RAD23B) expression in circulating tumor cells (CTCs) provides complementary clinical information. CTCs were prospectively evaluated in 166 blood samples (63 patients) with LARC undergoing NCRT. The primary objective was to verify if the absence of RAD23B/TYMS in CTCs would correlate with pathological complete response (pCR). Secondary objectives were to correlate CTC kinetics before (C1)/after NCRT (C2), in addition to the expression of transforming growth factor-β receptor I (TGF-βRI) with survival rates. CTCs were isolated by ISET and evaluated by immunocytochemistry (protein expression). At C1, RAD23B was detected in 54.1% of patients with no pCR and its absence in 91.7% of patients with pCR (p = 0.014); TYMS^- was observed in 90% of patients with pCR and TYMS⁺ in 51.7% without pCR (p = 0.057). Patients with CTC2 > CTC1 had worse disease-free survival (DFS) (p = 0.00025) and overall survival (OS) (p = 0.0036) compared with those with CTC2 ≤ CTC1. TGF-βRI expression in any time correlated with worse DFS (p = 0.059). To conclude, RAD23B/TYMS and CTC kinetics may facilitate the personalized treatment of LARC.

Can the mesorectal fat tissue volume be used as a predictive factor in foreseeing the response to neoadjuvant chemoradiotherapy in rectum cancer? A CT-based preliminary study

PURPOSE

This study was to investigate the effect of mesorectal fat tissue volume (MRV) on the pathological response to neoadjuvant chemoradiotherapy (nCRT) in patients with locally advanced rectal cancer.

METHODS

88 patients who had been diagnosed with locally advanced rectal cancer between January 2017 and June 2020 were reviewed retrospectively. The total abdominal, subcutaneous, visceral, and mesorectal fatty tissue components were measured semiquantitatively by two radiologists using computed tomography (CT)-based findings. The patients were divided into two groups as those with and without a pathological response to nCRT. The relationship of MRV with the other fat tissue components of the body was also evaluated.

RESULTS

We performed a retrospective analysis of 88 patients (mean age 62.7 years [range, 33-90 years]; 31 males and 57 females). A positive response to nCRT was present in 47 patients. There were 59 patients with stage 3 disease. 46 patients demonstrated lymph node involvement. The mean MRV was 69.6 ± 31.0 ml in no-response group and 105.8 ± 47.5 ml in response-positive patients (p < 0.05). MRV showed the highest correlation with visceral fat volume (VFV). There was a negative correlation between the MRV and the N stage. A cut-off value of ≥ 69.4 for MRV predicted the repsonse to nCRT, with 82.9% sensitivity and 58.5% specificity [AUC: 0.757 (0.653-0.842), p < 0.001] in receiver operating characteristic (ROC) curve analysis CONCLUSIONS: MRV can be used as a novel parameter in predicting of pathological response to nCRT in locally advanced rectal cancer patients.

Computertomography-Based Prediction of Complete Response Following Neoadjuvant Chemoradiotherapy of Locally Advanced Rectal Cancer

Therapeutic strategies for patients with locally advanced rectal cancer (LARC) who are achieving a pathological complete response (pCR) after neoadjuvant radio-chemotherapy (neoCRT) are being increasingly investigated. Recent trials challenge the current standard therapy of total mesorectal excision (TME). For some patients, the treatment strategy of “watch-and-wait” seems a preferable procedure. The key factor in determining individual treatment strategies following neoCRT is the precise evaluation of the tumor response. Contrast-enhanced computer tomography (ceCT) has proven its ability to discriminate benign and malign lesions in multiple cancers. In this study, we retrospectively analyzed the ceCT based density of LARC in 30 patients, undergoing neoCRT followed by TME. We compared the tumors´ pre- and post-neoCRT density and correlated the results to the amount of residual vital tumor cells in the resected tissue. Overall, the density decreased after neoCRT, with the highest decrease in patients achieving pCR. Densitometry demonstrated a specificity of 88% and sensitivity of 68% in predicting pCR. Thus, we claim that ceCT based densitometry is a useful tool in identifying patients with LARC who may benefit from a “watch-and-wait” strategy and suggest further prospective studies.

Complete pathological response in rectal cancer utilising novel treatment strategies for neo-adjuvant therapy: A systematic review

BACKGROUND

Locally advanced rectal cancer is routinely treated with neo-adjuvant long course chemoradiotherapy or short course radiotherapy, followed by total mesorectal excision. Not all patients respond to this treatment and there has been an emergence of novel treatment strategies designed to improve outcomes for these patients. This systematic review aims to assess the current novel neo-adjuvant treatment strategies being utilised in the treatment of patients with rectal cancer and how these impact pathological complete response (pCR) rates.

METHODS

A systematic review of the literature was performed to evaluate pathological response in patients with rectal cancer receiving novel neo-adjuvant therapy. EMBASE and Medline electronic databases were searched for relevant articles. Articles published between January 2008 and February 2019 were retrieved. Included studies underwent critical appraisal and complete pathological response rates were recorded.

RESULTS

Of the initial 1074 articles identified, 217 articles fulfilled the inclusion criteria, of these 60 articles (4359 patients) were included. Neo-adjuvant therapy delivered included novel long course chemoradiation therapy, neoadjuvant chemotherapy alone, addition of a biological agent, total neo-adjuvant therapy, novel short course radiation therapy and studies utilising biomarkers to select patients for therapy. Complete pathological response rates ranged from 0 to 60%.

CONCLUSION

A validated novel neo-adjuvant therapy that significantly increases pCR rates in patients with rectal cancer has not been identified.

Studying local tumour heterogeneity on MRI and FDG-PET/CT to predict response to neoadjuvant chemoradiotherapy in rectal cancer

OBJECTIVE

To investigate whether quantifying local tumour heterogeneity has added benefit compared to global tumour features to predict response to chemoradiotherapy using pre-treatment multiparametric PET and MRI data.

METHODS

Sixty-one locally advanced rectal cancer patients treated with chemoradiotherapy and staged at baseline with MRI and FDG-PET/CT were retrospectively analyzed. Whole-tumour volumes were segmented on the MRI and PET/CT scans from which global tumour features (T2W_volume/T2W_entropy/ADC_mean/SUV_mean/TLG/CT_mean-HU) and local texture features (histogram features derived from local entropy/mean/standard deviation maps) were calculated. These respective feature sets were combined with clinical baseline parameters (e.g. age/gender/TN-stage) to build multivariable prediction models to predict a good (Mandard TRG1-2) versus poor (Mandard TRG3-5) response to chemoradiotherapy. Leave-one-out cross-validation (LOOCV) with bootstrapping was performed to estimate performance in an 'independent' dataset.

RESULTS

When using only imaging features, local texture features showed an AUC = 0.81 versus AUC = 0.74 for global tumour features. After internal cross-validation (LOOCV), AUC to predict a good response was the highest for the combination of clinical baseline variables + global tumour features (AUC = 0.83), compared to AUC = 0.79 for baseline + local texture and AUC = 0.76 for all combined (baseline + global + local texture).

CONCLUSION

In imaging-based prediction models, local texture analysis has potential added value compared to global tumour features to predict response. However, when combined with clinical baseline parameters such as cTN-stage, the added value of local texture analysis appears to be limited. The overall performance to predict response when combining baseline variables with quantitative imaging parameters is promising and warrants further research.

KEY POINTS

• Quantification of local tumour texture on pre-therapy FDG-PET/CT and MRI has potential added value compared to global tumour features to predict response to chemoradiotherapy in rectal cancer. • However, when combined with clinical baseline parameters such as cTN-stage, the added value of local texture over global tumour features is limited. • Predictive performance of our optimal model-combining clinical baseline variables with global quantitative tumour features-was encouraging (AUC 0.83), warranting further research in this direction on a larger scale.

Diagnosis of Clinical Complete Response by Probe-Based Confocal Laser Endomicroscopy (pCLE) After Chemoradiation for Advanced Rectal Cancer

BACKGROUND

Neoadjuvant chemoradiotherapy (nCRxt) followed by radical surgery is the optimal treatment for advanced rectal adenocarcinoma. Patients with clinical complete response (cCR) may be followed closely without immediate surgery. Probe-based confocal laser endomicroscopy (pCLE) is a real-time in vivo method that allows acquisition of optical biopsies with 1000 times magnification, evaluating both epithelial and vascular patterns.

AIM

To evaluate the role of pCLE in the diagnosis of cCR after nCRxt for advanced rectal adenocarcinoma.

METHODS

pCLE was performed in 47 patients with locally advanced rectal adenocarcinoma (T3/T4, or N+) who underwent nCRxt (5-fluorouracil, 5040 cGy).

RESULTS

Twenty-seven (57.5%) patients were men, and the mean age was 62.8 years. Thirty-seven had partial response confirmed by pCLE. Ten (21.3%) patients had good endoscopic response and presented small ulcer (n = 5) or residual scar (n = 5). After nCRxt, the essential features to differentiate malignancy from post-radiation alterations at pCLE were the presence of irregular crypts, budding, back-to-back glands, cribriform pattern, increased vessel/crypt ratio, and fluorescein leakage. A scoring system was created considering these epithelial and vascular features, with high accuracy for differentiating patients with complete response from those with residual neoplasia (p < 0.00001). pCLE sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 100%, 71.4%, 95.2%, 100%, and 95.7%, respectively.

CONCLUSIONS

(1) pCLE evaluation of epithelial and vascular features may improve the diagnosis of cCR and may alter patient management; (2) pCLE might be valuable for identifying patients with advanced rectal cancer who will benefit from watch and wait strategy, avoiding immediate surgical treatment.

Neoadjuvant rectal (NAR) score: Value evaluating the efficacy of neoadjuvant therapy and prognostic significance after surgery?

INTRODUCTION

The Neoadjuvant rectal (NAR) score is a new surrogate endpoint to be used in clinical trials for early determination of treatment response to different preoperative therapies. The aim is to further validate the NAR-score, primarily developed using chemoradiotherapy (CRT) with a delay to surgery 6-8 weeks, and explore its value using other schedules.

MATERIALS AND METHODS

The study included all 9978 patients diagnosed with non-metastasized RC in 2007-2015 that had undergone surgery and was registered in the Swedish Colorectal Cancer Registry. The patients of interest had either short-course radiotherapy (scRT)/CRT + delayed surgery, long-course radiotherapy (RT) + delayed surgery, (C)RT + additional chemotherapy, primary surgery, or scRT + immediate surgery. The scRT/CRT + delayed surgery groups were further divided based on time to surgery.

RESULTS

Mean NAR-score differed significantly (p < 0.0001) between different treatments. (C)RT + additional chemotherapy had the lowest mean score of 16.3 and CRT + delayed surgery had 17.7. There was a significant difference (p < 0.05) in overall survival (OS) and time to recurrence (TTR) of patients with a Low NAR-score (<8) compared to those with a High score (>16) for both CRT- and scRT, with a stronger correlation for CRT-patients. C-index for the NAR-score model (0.623) was not superior to when only pathological T- and N-stage was used (0.646).

CONCLUSIONS

The NAR-score is prognostic, but it is not better than pT- and pN-stage. However, the NAR-score can still discriminate between two treatments that have different cell killing effect and may still be of value in clinical trials as an easier method than pT- and N-stage.

A Comprehensive Evaluation of Associations Between Routinely Collected Staging Information and The Response to (Chemo)Radiotherapy in Rectal Cancer

Simple Summary

Rectal cancer patients are often treated with radiotherapy, either alone or combined with chemotherapy, prior to surgery to enable radical surgery on a non-resectable tumor or to lower the recurrence risk. For some patients, the tumor disappears completely after preoperative treatment, while others experience little or no benefit. Accurate prediction of therapy response before treatment is of great importance for a personalized treatment approach and intentional organ preservation. We performed a comprehensive evaluation of the predictive capacity of all routinely collected staging information at diagnosis in a population-based, completely staged patient material of 383 patients representing a real-life clinical situation. Size or stage of the rectal tumor were independent predictors of excellent response irrespective of preoperative treatment, with small/early-stage tumors being significantly more likely to reach a complete response. Levels of the tumor marker carcinoembryonic antigen (CEA) above upper normal limit halved the chance of response.

Abstract

Radiotherapy (RT) or chemoradiotherapy (CRT) are frequently used in rectal cancer, sometimes resulting in complete tumor remission (CR). The predictive capacity of all clinical factors, laboratory values and magnetic resonance imaging parameters performed in routine staging was evaluated to understand what determines an excellent response to RT/CRT. A population-based cohort of 383 patients treated with short-course RT (5 × 5 Gy in one week, scRT), CRT, or scRT with chemotherapy (scRT+CT) and having either had a delay to surgery or been entered into a watch-and-wait program were included. Complete staging according to guidelines was performed and associations between investigated variables and CR rates were analyzed in univariate and multivariate analyses. In total, 17% achieved pathological or clinical CR, more often after scRT+CT and CRT than after scRT (27%, 18% and 8%, respectively, p < 0.001). Factors independently associated with CR included clinical tumor stage, small tumor size (<3 cm), tumor level, and low CEA-value (<3.8 μg/L). Size or stage of the rectal tumor were associated with excellent response in all therapy groups, with small or early stage tumors being significantly more likely to reach CR (p = 0.01 (scRT), p = 0.01 (CRT) and p = 0.02 (scRT+CT). Elevated level of carcinoembryonic antigen (CEA) halved the chance of response. Extramural vascular invasion (EMVI) and mucinous character may indicate less response to RT alone.

Prognostic value of changes in serum carcinoembryonic antigen levels for preoperative chemoradiotherapy response in locally advanced rectal cancer

BACKGROUND

Preoperative chemoradiotherapy (CRT) is a standard treatment modality for locally advanced rectal cancer. However, CRT alone cannot improve overall survival. Approximately 20% of patients with CRT-resistant tumors show disease progression. Therefore, predictive factors for treatment response are needed to identify patients who will benefit from CRT. We theorized that the prognosis may vary if patients are classified according to pre- to post-CRT changes in carcinoembryonic antigen (CEA) levels.

AIM

To identify patients with locally advanced rectal cancer for preoperative chemoradiotherapy based on carcinoembryonic antigen levels.

METHODS

We retrospectively included locally advanced rectal cancer patients who underwent preoperative CRT and curative resection between 2011 and 2017. Patients were assigned to groups A, B, and C based on pre- and post-CRT serum CEA levels: Both > 5; pre > 5 and post ≤ 5; and both ≤ 5 ng/mL, respectively. We compared the response to CRT based on changes in serum CEA levels. Receiver operating characteristic curve analysis was performed to determine optimal cutoff for neutrophil–lymphocyte ratio and platelet–lymphocyte ratio. Multivariate logistic regression analysis was used to evaluate the prognostic factors for pathologic complete response (pCR)/good response.

RESULTS

The cohort comprised 145 patients; of them, 27, 43, and 65 belonged to groups A, B, and C, respectively, according to changes in serum CEA levels before and after CRT. Pre- (P < 0.001) and post-CRT (P < 0.001) CEA levels and the ratio of down-staging (P = 0.013) were higher in Groups B and C than in Group A. The ratio of pathologic tumor regression grade 0/1 significantly differed among the groups (P = 0.003). Group C had the highest number of patients showing pCR (P < 0.001). Most patients with pCR showed pre- and post-CRT CEA levels < 5 ng/mL (P < 0.001, P = 0.008). Pre- and post-CRT CEA levels were important risk factors for pCR (OR = 18.71; 95%CI: 4.62–129.51, P < 0.001) and good response (OR = 5.07; 95%CI: 1.92–14.83, P = 0.002), respectively. Pre-CRT neutrophil–lymphocyte ratio and post-CRT T ≥ 3 stage were also prognostic factors for pCR or good response.

CONCLUSION

Pre- and post-CRT CEA levels, as well as change in CEA levels, were prognostic markers for treatment response to CRT and may facilitate treatment individualization for rectal cancer.

Genetic Variants of the TERT Gene, Telomere Length, and Circulating TERT as Prognostic Markers in Rectal Cancer Patients

Single-nucleotide polymorphisms (SNPs) in the TERT gene can affect telomere length and TERT expression and have been associated with risk and/or outcome for several tumors, but very few data are available about their impact on rectal cancer. Eight SNPs (rs2736108, rs2735940, rs2736098, rs2736100, rs35241335, rs11742908, rs2736122 and rs2853690), mapping in regulatory and coding regions of the TERT gene, were studied in 194 rectal cancer patients to evaluate their association with constitutive telomere length, circulating TERT mRNA levels, response to neoadjuvant chemoradiotherapy (CRT) and disease outcome. At diagnosis, the rs2736100CC genotype was associated with longer telomeres measured pre-CRT, while the rs2736100CC, rs2736108TT and rs2735940AA were associated with greater telomere erosion evaluated post-CRT. The rs2736108CC and rs2853690AA/GG genotypes, respectively associated with lower telomere erosion and lower levels of circulating TERT post-CRT, were also independently associated with a better response to therapy [OR 4.6(1.1-19.1) and 3.0(1.3-6.9)]. Overall, post-CRT, low levels (≤ median value) of circulating TERT and its stable/decreasing levels compared to those pre-CRT, were independently associated with a better response to therapy [OR 5.8(1.9-17.8) and 5.3(1.4-19.4), respectively]. Furthermore, post-CRT, patients with long telomeres (>median value) and low levels of circulating TERT had a significantly lower risk of disease progression [HR 0.4(0.1-0.9) and 0.3(0.1-0.8), respectively]. These findings suggest that TERT SNPs could be a useful tool for improving the selection of patients who could benefit from CRT and support the role of telomere length and circulating TERT mRNA levels as useful markers for monitoring the response to therapy and disease outcome in rectal cancer patients.

Serial Circulating Tumor DNA in Predicting and Monitoring the Effect of Neoadjuvant Chemoradiotherapy in Patients with Rectal Cancer: A Prospective Multicenter Study

PURPOSE

We investigated the value of circulating tumor DNA (ctDNA) in predicting tumor response to neoadjuvant chemoradiotherapy (nCRT), monitoring tumor burden, and prognosing survival in patients with locally advanced rectal cancer (LARC).

EXPERIMENTAL DESIGN

This prospective multicenter trial recruited 106 patients with LARC for treatment with nCRT followed by surgery. Serial ctDNAs were analyzed by next-generation sequencing at four timepoints: at baseline, during nCRT, presurgery, and postsurgery.

RESULTS

In total, 1,098 mutations were identified in tumor tissues of the 104 patients being analyzed (median, seven mutations/patient). ctDNA was detected in 75%, 15.6%, 10.5%, and 6.7% of cases at the four timepoints, respectively. None of the 29 patients with pathologic complete response (ypCR) had preoperative ctDNA detected. The preoperative ctDNA-positive rate was significantly lower in the well-responded patients with pathologic tumor regression grade of ypCAP 0-1 than ypCAP 2-3 group (P < 0.001), lower in ypCR than non-ypCR group (P = 0.02), and lower in pathologic T stage (ypT) 0-2 than ypT 3-4 group (P = 0.002). With a median follow-up of 18.8 months, 13 patients (12.5%) experienced distant metastasis. ctDNA positivity at all four timepoints was associated with a shorter metastasis-free survival (MFS; P < 0.05). Multivariate analyses showed that the median variant allele frequency (VAF) of mutations in baseline ctDNA was a strong independent predictor of MFS (HR, 1.27; P < 0.001).

CONCLUSIONS

We show that ctDNA is a real-time monitoring indicator that can accurately reflect the tumor burden. The median VAF of baseline ctDNA is a strong independent predictor of MFS.

Preoperative Fibrinogen-Albumin Ratio Index (FARI) is a Reliable Prognosis and Chemoradiotherapy Sensitivity Predictor in Locally Advanced Rectal Cancer Patients Undergoing Radical Surgery Following Neoadjuvant Chemoradiotherapy

Background

Inflammatory response and nutritional status are associated with cancer development and progression. The purpose of this study was to explore whether the preoperative fibrinogen-albumin ratio index (FARI) is related to prognosis and chemoradiotherapy outcome of radical surgery after neoadjuvant chemoradiotherapy (NCRT) in patients with locally advanced rectal cancer (LARC).

Methods

In total, 123 patients with LARC who underwent radical surgery after NCRT between June 2012 and December 2018 were collected in this study. Time-dependent receiver operating characteristic (ROC) curve analysis was made to evaluate the ability of the markers for forecasting prognosis. The correlation between FARI and clinicopathological parameters was analyzed. The Kaplan-Meier survival analysis, univariate and multivariate analysis based on Cox proportional hazards models, and subgroup analysis were performed to evaluate overall survival (OS) and disease-free survival (DFS). A nomogram was constructed to evaluate the predictive role of FARI in DFS.

Results

The ROC curve analysis showed that the ability of FARI on DFS prediction was superior to those of other inflammatory markers and carcinoembryonic antigen (CEA) (P<0.05). Based on the Youden's index, the optimal cut-off value of FARI was 8.8%. High FARI patients (>8.8%) showed a poor response to NCRT and a decreased DFS rate (P<0.05). In addition, multivariate analysis revealed that FARI (HR=3.098, P=0.033), neutrophil-to-lymphocyte ratio (NLR), and postoperative T stage were independent prognostic factors for DFS in TNM stage III LARC patients. However, FARI failed to distinguish patients with poor OS. Harrell's concordance index (C-index) of the nomogram containing FARI (0.807) was obviously higher than that without it (0.732) among LARC patients who underwent radical surgery after NCRT. Moreover, multivariate analysis revealed FARI (OR=3.044, P=0.012) as an independent predictor for response to NCRT.

Conclusion

Among LARC patients who underwent radical surgery after NCRT, preoperative FARI is an independent prognostic factor for DFS and an independent predictor for response to NCRT.

The role of readout-segmented echo-planar imaging-based diffusion-weighted imaging in evaluating tumor response of locally advanced rectal cancer after neoadjuvant chemoradiotherapy

BACKGROUND

Accurate assessment of tumor response in rectal cancer could help individualize treatment.

PURPOSE

To evaluate the role of diffusion-weighted imaging (DWI) based on readout-segmented echo-planar imaging (rs-EPI) in assessing tumor response after neoadjuvant chemoradiotherapy (CRT) in locally advanced rectal cancer (LARC).

MATERIAL AND METHODS

Sixty-three patients with LARC who received neoadjuvant CRT and surgery were enrolled retrospectively. They all underwent pre- and post-CRT magnetic resonance examinations, including DWI using rs-EPI. According to pathological results, patients were grouped as pathological complete responder (pCR, n = 16) and non-pCR (n = 47). Visual assessment of residual tumor and whole-tumor histogram analysis of pre- and post-CRT apparent diffusion coefficient (ADC) map was performed by two radiologists; tumor volume on ADC map was also recorded.

RESULTS

Overall inter-observer agreement was good for histogram analysis (ICC = 0.543-0.999). Tumor volume reduction rate on ADC map showed no significant difference between the two groups (P = 0.468). Post-CRT mean, quantile values, and their percentage changes were higher in the pCR group (all P < 0.001). Post-CRT mean value had a good diagnostic power in selecting pCR (AUC = 0.855), with a cut-off value of 1.345 × 10^-3 mm²/s, yielding a sensitivity of 83%, specificity of 81.3%. Post-CRT 95% quantile value had the highest AUC (AUC = 0.868) among quantile values, and a higher specificity (87.5% vs. 81.3%) than mean value with comparable overall diagnostic performance (P = 0.563). Visual assessment showed a sensitivity of 85.1%, specificity of 68.8% in selecting pCR.

CONCLUSION

Quantitative ADC value of rs-EPI DWI could reliably evaluate tumor response in patients with LARC. Post-CRT 95% quantile ADC value could help mean value to more accurately identify pCR.

Limited Role for Routine Restaging After Neoadjuvant Therapy in Locally Advanced Rectal Cancer

BACKGROUND

Although many patients with locally advanced rectal cancer undergo restaging imaging after neoadjuvant chemoradiotherapy and before surgery, the benefit of this practice is unclear. The purpose of this study was to examine the impact of reimaging on outcomes.

MATERIALS AND METHODS

We performed a retrospective analysis of consecutive patients with stage 2 and 3 rectal adenocarcinoma treated with neoadjuvant chemoradiotherapy between May 2005 and April 2018. Patient and disease characteristics, imaging, treatment, and oncologic outcomes were compared between those who underwent restaging and those who went directly to surgery. Predictors of outcomes and cost effectiveness of restaging were determined.

RESULTS

Of 224 patients, 146 underwent restaging. Six restaged patients had findings leading to a change in management. There was no difference in freedom from recurrence (P = 0.807) and overall survival (P = 0.684) based on restaging. Pretreatment carcinoembryonic antigen level >3 ng/mL (P = 0.010), clinical T stage 4 (P = 0.016), and pathologic T4 (P = 0.047) and N2 (P = 0.002) disease increased the risk of death, whereas adjuvant chemotherapy decreased the risk of death (P < 0.001) on multivariate analysis. Disease recurrence was lower with pelvic exenteration (P = 0.005) and in females (P = 0.039) and higher with pathologic N2 (P = 0.003) and N3 (P = 0.002) disease. The average cost of reimaging is $40,309 per change in management; however, $45 is saved per patient when downstream surgical costs are considered.

CONCLUSIONS

Imaging restaging after neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer rarely changes treatment and does not improve survival. In a subset of patients at higher risk for worse outcome, reimaging may be beneficial.

Pre-Treatment T2-WI Based Radiomics Features for Prediction of Locally Advanced Rectal Cancer Non-Response to Neoadjuvant Chemoradiotherapy: A Preliminary Study

Locally advanced rectal cancer (LARC) response to neoadjuvant chemoradiotherapy (nCRT) is very heterogeneous and up to 30% of patients are considered non-responders, presenting no tumor regression after nCRT. This study aimed to determine the ability of pre-treatment T2-weighted based radiomics features to predict LARC non-responders. A total of 67 LARC patients who underwent a pre-treatment MRI followed by nCRT and total mesorectal excision were assigned into training (n = 44) and validation (n = 23) groups. In both datasets, the patients were categorized according to the Ryan tumor regression grade (TRG) system into non-responders (TRG = 3) and responders (TRG 1 and 2). We extracted 960 radiomic features/patient from pre-treatment T2-weighted images. After a three-step feature selection process, including LASSO regression analysis, we built a radiomics score with seven radiomics features. This score was significantly higher among non-responders in both training and validation sets (p < 0.001 and p = 0.03) and it showed good predictive performance for LARC non-response, achieving an area under the curve (AUC) = 0.94 (95% CI: 0.82–0.99) in the training set and AUC = 0.80 (95% CI: 0.58–0.94) in the validation group. The multivariate analysis identified the radiomics score as an independent predictor for the tumor non-response (OR = 6.52, 95% CI: 1.87–22.72). Our results indicate that MRI radiomics features could be considered as potential imaging biomarkers for early prediction of LARC non-response to neoadjuvant treatment.

External validation of a 'response score' after neoadjuvant chemotherapy in patients with high-grade serous ovarian carcinoma with complete clinical response

OBJECTIVES

The chemotherapy response score (CRS) has been developed for measuring response to neoadjuvant chemotherapy in tubo-ovarian high-grade serous carcinoma. This study aimed to validate the ability of this three-tier scoring system of pathologic response on omental specimens to determine prognosis in a subgroups of patients who had clinical complete response to neoadjuvant chemotherapy.

METHODS

This was a retrospective study, conducted in women receiving interval debulking surgery at the Division of Gynecologic Oncology, between December 2007 and April 2017. Inclusion criteria were: high-grade serous ovarian cancer, FIGO stage IIIC/IV, platinum-based neoadjuvant chemotherapy, and clinical complete response after neoadjuvant chemotherapy (normalization in CA125 levels, disappearance of all target and non-target lesions according to RECIST 1.1). CRS was defined by a single pathology review and classified as previously reported: CRS1, no or minimal tumor response with fibroinflammatory changes limited to a few foci ranging from multifocal or diffuse regression-associated fibroinflammatory changes with viable tumor in sheets, or nodules to extensive regression-associated fibroinflammatory changes with multifocal residual tumor; CRS2, appreciable tumor response with viable tumor readily identifiable; and CRS3, complete absence of tumor or nodules with maximum size of 2 mm. CRS was analyzed according to clinical variables and survival.

RESULTS

A total of 108 patients were eligible for analysis. The average age was 65 (range 36-85) years. A total of 91 (84.3%) patients had stage IIIC disease and 17 (15.7%) patients had stage IV disease. No statistically significant differences were observed in terms of age, FIGO stage, CA125 serum levels, type of chemotherapy schedules, and number of cycles between the three groups. Patients in the CRS3 group had a longer median progression-free survival (25.8 months) compared with CRS2 or CRS 1 (20.3 vs 17.4 months, respectively; p=0.001). Median overall survival was 68.9 months for CRS3, 35.0 months for CRS2, and 45.9 months for CRS1 (p=0.034).

CONCLUSION

Complete or near-complete pathologic response assessed in the omental specimens of advanced epithelial ovarian carcinoma patients after neoadjuvant chemotherapy (CRS3) is predictive of prolonged progression-free and overall survival. In particular, this is true in women with a clinical complete response.

Pretreatment TACC3 expression in locally advanced rectal cancer decreases the response to neoadjuvant chemoradiotherapy

Chemoradiotherapy combined with surgical resection is the standard treatment for locally advanced rectal cancer, but not all the patients respond to neoadjuvant treatment. Transforming acidic coiled-coil protein-3 (TACC3) is frequently aberrantly expressed in rectal cancer tissue. In this study, we investigated whether TACC3 could serve as a biomarker predictive of the efficacy of chemoradiotherapy. In all, 152 rectal cancer patients with tumor tissue collected at biopsy and set aside before treatment were enrolled in this study. All patients received chemoradiotherapy and surgical resection. Immunohistochemically detected tumoral TACC3 expression significantly decreased sensitivity to chemoradiotherapy [risk ratio (RR) = 2.236, 95% confidence interval (CI): 1.447-3.456; P = 0.001] and thus the pathological complete response rate (P = 0.001). TACC3 knockdown using specific siRNA enhanced radiotherapy-induced decreases in proliferation and colony formation by HCT116 and SW480 cells and increased the incidence of radiotherapy-induced apoptosis. Cox multivariate analysis showed that TACC3 was a significant prognostic factor for overall survival (P = 0.017) and disease-free survival (P = 0.020). These findings suggest TACC3 expression may be predictive of chemoradiotherapy sensitivity and prognosis in locally advanced rectal cancer.

A Multigene Model for Predicting Tumor Responsiveness After Preoperative Chemoradiotherapy for Rectal Cancer

PURPOSE

Although preoperative chemoradiotherapy (PCRT) is regarded as a standard treatment for locally advanced rectal cancer, there is no reliable biomarker for predicting responsiveness to PCRT. We aimed to develop a biomarker model for predicting response to PCRT.

METHODS AND MATERIALS

We included 184 patients who received PCRT followed by surgical resection and categorized them as good responders (complete or near-complete regression) or poor responders (all other patients). Candidate gene mRNAs were isolated from formalin-fixed paraffin-embedded tumor specimens and analyzed using the NanoString nCounter gene expression assay. Stepwise logistic regression analysis was used to select genes in discovery and training phases. A quantitative radio-responsiveness prediction model was developed and validated using internal cross-validation groups, and the model's predictive value was assessed based on the area under the receiver operating characteristic curve (AUC).

RESULTS

By comparing the gene expressions between good and poor responders, we created a multigene mRNA model using FZD9, HRAS, ITGA7, MECOM, MMP3, NKD1, PIK3CD, and PRKCB. This panel showed good ability to predict treatment response (AUC: 0.846 for the whole data set). Internal cross-validation was performed to evaluate the model's predictive stability among 3 cohorts, which provided AUC values of 0.808-0.909. The satisfactory diagnostic performance of the radio-response prediction index persisted regardless of other clinicopathologic features such as clinical T or N stage, interval between radiation and surgery, and pretreatment carcinoembryonic antigen levels (P = .001, 95% CI, 0.686-0.905).

CONCLUSIONS

We developed a multigene mRNA-based biomarker model that allows prediction of rectal cancer response to PCRT, which may help identify patients who will benefit most from PCRT.

Current concepts in imaging for local staging of advanced rectal cancer

Imaging of rectal cancer has an increasingly pivotal role in the diagnosis, staging, and treatment stratification of patients with the disease. This is particularly true for advanced rectal cancers where magnetic resonance imaging (MRI) findings provide essential information that can change treatment. In this review we describe the rationale for the current imaging standards in advanced rectal cancer for both morphological and functional imaging on the baseline staging and reassessment studies. In addition the clinical implications and future methods by which radiologists may improve these are outlined relative to TNM8.