Predictors of Pathologic Complete Response in Rectal Cancer Patients Undergoing Total Mesorectal Excision After Preoperative Chemoradiation

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.

Predicting Factors of Complete Pathological Response in Locally Advanced Rectal Cancer

Background: Current treatment of choice for locally advanced rectal cancer is neoadjuvant chemoradiotherapy (neo-CRT) followed by surgical resection and adjuvant chemotherapy. Some patients may experience complete pathological response (cPR) after the neoadjuvant treatment. However, the predicting factors are still debated. Methods: In this registry-based retrospective cohort study, 258 patients with locally advanced rectal cancer were included. Patients were categorized into two groups with or without cPR. Logistic regression analysis was recruited to investigate the odds ratio for all independent variables, and those with significant results were included in multivariate regression analysis. Results: Achievement of cPR was 21.3%. The odds ratio of cPR was significantly lower when the tumor distance from the anal verge was>10 centimeters (OR=0.24, P=0.040). Also, the odds of cPR with N1 involvement in comparison with N0 involvement decreased for 0.41 (P=0.043). It was also true for patients with N2 involvement in comparison with N0 involvement (OR=0.31, P=0.031). Higher odds ratio of cPR was observed in patients who underwent surgery in>12 weeks after neo-CRT (OR=2.9, P=0.022). Furthermore, the odds of cPR decreased for 0.9 with increasing in carcinoembryonic antigen (CEA) level (P=0.044). Conclusion: Patients with rectal cancer in clinical stage II or lower, without the involvement of the lymphatic system at diagnosis, and with tumors located in the lower parts of the rectum, with lower levels of CEA, and longer duration between neo-CRT and surgery were more likely to achieve cPR after neo-CRT. With the current knowledge, the "wait and watch policy" is still debated and needs to be defined more precisely by upcoming studies.

Predictors of pathologic complete response in patients with residual flat mucosal lesions after neoadjuvant chemoradiotherapy for locally advanced rectal cancer

OBJECTIVE

The accurate prediction of tumor response to neoadjuvant chemoradiotherapy (nCRT) remains challenging. Few studies have investigated pathologic complete response (ypCR) prediction in patients with residual flat mucosal lesions after treatment. This study aimed to identify variables for predicting ypCR in patients with residual flat mucosal lesions after nCRT for locally advanced rectal cancer (LARC).

METHODS

Data of patients with residual flat mucosal lesions after nCRT who underwent radical resection between 2009 and 2015 were retrospectively collected from the LARC database at Peking University Cancer Hospital. Univariate and multivariate analyses of the association between clinicopathological factors and ypCR were performed, and a nomogram was constructed by incorporating the significant predictors.

RESULTS

Of the 246 patients with residual flat mucosal lesions included in the final analysis, 56 (22.8%) had ypCR. Univariate and multivariate analyses showed that pretreatment cT stage (pre-cT) ≤T2 (P=0.016), magnetic resonance tumor regression grade (MR-TRG) 1-3 (P=0.001) and residual mucosal lesion depth =0 mm (P<0.001) were associated with a higher rate of ypCR. A nomogram was developed with a concordance index (C-index) of 0.759 and the calibration curve showed that the nomogram model had good predictive consistency. The follow-up time ranged from 3.0 to 113.3 months, with a median follow-up time of 63.77 months. The multivariate Cox regression model showed that the four variables in the nomogram model were not risk factors for disease-free survival (DFS) or overall survival (OS).

CONCLUSIONS

Completely flat mucosa, early cT stage and good MR-TRG were predictive factors for ypCR instead of DFS or OS in patients with LARC with residual flat mucosal lesions after nCRT. Endoscopic mucosal re-evaluation before surgery is important, as it may contribute to decision-making and facilitate nonoperative management or organ preservation.

Pre-Treatment Computed Tomography Radiomics for Predicting the Response to Neoadjuvant Chemoradiation in Locally Advanced Rectal Cancer: A Retrospective Study

Background and Purpose

Computerized tomography (CT) scans are commonly performed to assist in diagnosis and treatment of locally advanced rectal cancer (LARC). This study assessed the usefulness of pretreatment CT-based radiomics for predicting pathological complete response (pCR) of LARC to neoadjuvant chemoradiotherapy (nCRT).

Materials and Methods

Patients with LARC who underwent nCRT followed by total mesorectal excision surgery from July 2010 to December 2018 were enrolled in this retrospective study. A total of 340 radiomic features were extracted from pretreatment contrast-enhanced CT images. The most relevant features to pCR were selected using the least absolute shrinkage and selection operator (LASSO) method and a radiomic signature was generated. Predictive models were built with radiomic features and clinico-pathological variables. Model performance was assessed with decision curve analysis and was validated in an independent cohort.

Results

The pCR was achieved in 44 of the 216 consecutive patients (20.4%) in this study. The model with the best performance used both radiomics and clinical variables including radiomic signatures, distance to anal verge, lymphocyte-to-monocyte ratio, and carcinoembryonic antigen. This combined model discriminated between patients with and without pCR with an area under the curve of 0.926 and 0.872 in the training and the validation cohorts, respectively. The combined model also showed better performance than models built with radiomic or clinical variables alone.

Conclusion

Our combined predictive model was robust in differentiating patients with and without response to nCRT.

Dose-dependent expression of extracellular microRNAs in HCT116 colorectal cancer cells exposed to high-dose-rate ionising radiation

Biomarkers of tumour response to radiotherapy may help optimise cancer treatment. The aim of the present study was to identify changes in extracellular microRNAs (miRNAs) as a biomarker of radiation-induced damage to human colorectal cancer cells. HCT116 cells were exposed to increasing doses of X-rays, and extracellular miRNAs were analysed by microarray. The results were correlated with the frequency of micronuclei. A total of 59 miRNAs with a positive correlation and 4 with a negative correlation between dose (up to 6 Gy) and extracellular miRNA expression were identified. In addition, for doses between 0 and 10 Gy, 12 miRNAs among those 59 miRNAs with a positive correlation were identified; for these extracellular miRNAs, a significantly positive correlation was observed between their expression and the frequency of micronuclei for doses up to 10 Gy. These results suggest that specific miRNAs may be considered as cell damage markers and may serve as secreted radiotherapy response biomarkers for colorectal cancer; however, the results must be further validated in serum samples collected from patients undergoing radiotherapy.

Concurrent use of statins and neoadjuvant chemoradiotherapy for rectal cancer: a systematic review and meta-analysis

PURPOSE

Statins are used primarily in patients with cardiovascular disease. More recently, they have demonstrated benefit in oncology patients. In vitro models have shown decreased rectal tumor cell viability in cells receiving chemoradiation and statin therapy. In vivo models have been less clear. This study aims to elucidate the impact of concurrent use of statins on the efficacy of neoadjuvant therapy for rectal cancer.

METHODS

Search of Medline, EMBASE, and CENTRAL was performed. Articles were included if they reported complete pathological response (pCR), long-term oncologic outcomes, or chemoradiotherapy-induced toxicity in patients with rectal cancer receiving concurrent statin and neoadjuvant therapy. A pairwise meta-analyses was performed using inverse variance random effects.

RESULTS

From 1564 citations, six studies with 726 patients on statin therapy (24.5% female, age: 63.6 years) and 1863 patients not on statin therapy (35.6% female, age: 60.9 years) were included. There was no significant difference in pCR rate between patients on statin therapy and patients not on statin therapy (RR 1.23, 95%CI 0.98-1.54, p = 0.08). Similarly, no difference existed between groups in long-term oncologic outcomes (5-year overall survival: RR 1.03, 95%CI 0.86-1.24, p = 0.75; 5-year disease-free survival: RR 1.04, 95%CI 0.85-1.26, p = 0.73). Chemoradiotherapy-induced toxicities were similar between groups.

CONCLUSION

The concurrent use of statin and neoadjuvant therapy did not significantly impact short- or long-term oncologic outcomes in patients with rectal cancer. Yet, despite pooling of data, this study remained inadequately powered. Larger, prospective studies are required to further elucidate the impact of statins on patients undergoing neoadjuvant therapy for rectal cancer.

Association Between Pathological Complete Response and Tumor Location in Patients with Rectal Cancer After Neoadjuvant Chemoradiotherapy, a Prospective Cohort Study

Background: Colorectal cancers are the third common malignancies after lung and breast neoplasms. Some contributing factors for pathological complete response (pCR) to neoadjuvant therapy of rectal cancer have been defined. Despite various studies in this era, there are few studies on the location of tumors. Objectives: Regarding the high prevalence of colorectal cancer in Iran and the importance of neoadjuvant chemoradiation for survival and morbidity, this study was carried out to determine the association between pathologic complete response and tumor location in patients with rectal cancer after neoadjuvant chemoradiotherapy. Methods: In this prospective cohort, 100 cases with rectal adenocarcinoma from 2017 to 2019 were enrolled. Distance between anal verge and tumor was measured by clinical examination, colonoscopy, endo-sonography, and MRI. Tumors were defined as distal (less than 5 cm from the anal verge) and none distal (more than 5 cm from the anal verge). Another subdivision was inferior (0 - 4.99 cm), middle (5 - 9.99 cm), and superior (10 - 15 cm). The pathological response was compared across the groups. Results: In this study, the pCR was seen in 30%. In univariate analysis body mass index (BMI), grade, N-stage, and distance from anal verge were related to pCR. In cases with BMI over 25 kg/m2 and in tumors with low to medium grade N0/N1, and distance less than 5 cm from the anal verge (low lying tumors) the pCR to neoadjuvant treatment was higher. In multivariate analysis tumor grade, N stage, and distance from anal verge were still related to pCR. Conclusions: According to the obtained results in this study, there may be some association between rectal tumor location and pathologic complete response.

Time interval between neoadjuvant radio-chemotherapy and surgery in rectal cancer: is the long interval correct for all patients?

BACKGROUND

Optimal time between neoadjuvant radio-chemotherapy period and surgery remains controversial in patients with rectal cancer: an increasing number of studies show results in favour of a long interval.

METHODS

We conducted a retrospective analysis of the cases of low-middle rectal adenocarcinoma undergoing neoadjuvant RT-CT and surgery: the primary endpoint was the complete pathological response rate and the secondary endpoint the rate of complications. We analysed cases from 1/01/2003 to 31/12/2018 divided in two periods: from 2003 to 2010 (23 pts) and from 2011 to 2018 (23 pts). The two periods were characterised by two different surgical teams which use different time intervals (≤vs>8 weeks).

RESULTS

The pCR rate is 21.7% in both groups; as regards the complications, the difference between the two groups is in grade IIIb: 8.7% in the first group and 17.4% in the second group (p 0.66).

CONCLUSIONS

Although our study is based on a small number of patients, it shows the same rate of pCR with respect to two different time intervals; this suggests the need for studies based on the division of patients into subgroups and the evaluation of different time intervals in order to reach the best oncological outcomes.

Clinical predictors of pathological good response in locally advanced rectal cancer

Purpose

The aim of this study was to identify the clinical predictors of pathological good response (PGR) after neoadjuvant chemoradiotherapy (nCRT) in locally advanced rectal cancer (LARC) to clarify the indications for local excision.

Methods and materials

A total of 173 patients with LARC (cT3–4/N +) who were treated with nCRT followed by surgery were enrolled in our retrospective study. Patients were categorized into two groups according to the different tumor responses of surgical pathology. Stage ypT0–1N0 was defined as the group with PGR, and stage ypT2–4N0/ypTanyN + was the defined as the pathological poor response (PPR) group, and the potential predictors were compared.

Results

Of 173 patients, PGR was achieved in 57 patients (32.95%). The distance from the inferior margin of the tumor to the anal verge, cT classification, pretreatment carcinoembryonic antigen (CEA) and the interval from the end of radiation to surgery were correlated with pathological response. In the multivariate analysis, the distance from anal verge < 5 cm (OR = 0.443, p = 0.019), pretreatment CEA < 5 ng/mL (OR = 0.412, p = 0.015) and the interval from the end of radiation to surgery ≥ 84 days (OR = 2.652, p = 0.005) were independent predictors of PGR.

Conclusions

The distance from the inferior margin of the tumor to the anal verge, pretreatment CEA and the interval from the end of radiation to surgery were significant predictors of PGR in LARC. A prospective study is needed to further validate these results in the future.

Neoadjuvant Chemoradiotherapy and Tumor Recurrence in Patients with Early T-Stage Cancer of the Lower Rectum

BACKGROUND

The role neoadjuvant chemoradiotherapy (nCRT) plays in oncological outcomes in early T-stage rectal cancer is uncertain. The present work aims to clarify prognostic outcomes by estimating the effect of nCRT on tumor recurrence prior to major surgery compared with major surgery alone.

PATIENTS AND METHODS

Prospectively collected data were retrospectively analyzed for patients diagnosed with localized rectal adenocarcinoma ≤ 8 cm from the anal verge, with final histopathology ≤ T2 (≤ ypT2/≤ pT2), regardless of magnetic resonance imaging staging, between 1990 and 2017. As the effect of nCRT on recurrence varied over time, thereby violating the Cox proportional hazards assumption, the effect of nCRT on recurrence hazards was estimated using a time-varying multivariate Cox model over two separate time intervals (≤ 1 year and > 1 year postsurgery) by nCRT.

RESULTS

Long-course nCRT was associated with a 5.6-fold increase in the hazard of recurrence ≤ 1 year postsurgery [hazard ratio (HR) 5.6; 95% confidence interval (CI) 1.2-24.9; P = 0.02], but there was no increase in recurrence hazards > 1 year (HR 0.84; 95% CI 0.4-2.0; P = 0.70). In subgroup analysis restricted to ≤ mrT2/≤ ypT2 and ≤ pT2 tumors (omitting > mrT2 tumors), the effect of nCRT on recurrence no longer varied over time, indicating that tumor heterogeneity was responsible for the observed increased recurrence hazards ≤ 1 year postsurgery; That is, > mrT2 tumors that were downstaged to ≤ ypT2 after nCRT were responsible for the time-varying effects of nCRT and increased recurrence hazards ≤ 1 year postsurgery. Subsequently, no difference was found in prognostic outcomes either with or without nCRT before surgery in the homogeneous population of ≤ mrT2/≤ ypT2 and ≤ pT2 tumors.

CONCLUSIONS

No evidence was found to indicate that nCRT prior to surgery reduces tumor recurrence in early T-stage lower rectal cancer compared with surgery alone.

Prediction of tumor response of rectal cancer cells via 3D cell culture and in vitro cytotoxicity assay before initiating preoperative chemoradiotherapy

The aim of the present study was to investigate the utility of 3D cell culture and in vitro cytotoxicity assays, performed using cells derived from biopsies obtained prior to the initiation of preoperative chemoradiotherapy (preop-CRT), in predicting tumor response to chemoradiotherapy following preop-CRT in rectal cancer. Biopsies were obtained from 49 patients with locally advanced rectal cancer that underwent preop-CRT between August 2015 and March 2017. Tumor tissue was obtained before initiating preop-CRT. The response to chemoradiation was assessed by in vitro cytotoxicity assay following 3D cell culture and radiation treatment. The associations between the results from the cytotoxicity assay, and tumor regression grade (TRG) and yp node (ypN) positivity were investigated. Among 49 patients, 26 patients were available for analysis. Cytotoxicity ranged from 25.5-72.6% (median, 47.6%). There was no difference in cytotoxicity according to the TRGs 1-5 (P=0.940), or good tumor response (TRGs 1-2 vs. TRGs 3-5; P=0.729). However, there was a significant difference in cytotoxicity between the ypN-negative and -positive groups (53.2±14.1 and 38.7±10.1, respectively; P=0.021). Following dichotomization of patients with 45% cut-off value, the cytotoxicity assay was the only factor that predicted ypN positivity in multivariate analysis (odds ratio, 13; 95% confidence interval, 1.2-133.2; P=0.031). In conclusion, the cytotoxicity assay using the 3D cell culture method can be used to predict tumor response, particularly ypN positivity, in patients with rectal cancer who are scheduled for preop-CRT.

Circulating Biomarkers for Response Prediction of Rectal Cancer to Neoadjuvant Chemoradiotherapy

Rectal cancer response to neoadjuvant Chemoradiotherapy (pCRT) is highly variable. In fact, it has been estimated that only about 21 % of patients show pathologic Complete Response (pCR) after therapy, while in most of the patients a partial or incomplete tumour regression is observed. Consequently, patients with a priori chemoradioresistant tumour should not receive the treatment, which is associated with substantial adverse effects and does not guarantee any clinical benefit. For Locally Advanced Rectal Cancer Patients (LARC), a standardized neoadjuvant treatment protocol is applied, the identification and the usefulness of prognostic or predictive biomarkers can improve the antitumoural treatment strategy, modifying the sequence, dose, and combination of radiotherapy, chemotherapy and surgical resection. For these reasons, a growing number of studies are actually focussed on the discovery and investigation of new predictive biomarkers of response to pCRT. In this review, we have selected the most recent literature (2012-2017) regarding the employment of blood-based biomarkers potentially predicting pCR in LARC patients and we have critically discussed them to highlight their real clinical benefit and the current limitations of the proposed methodological approaches.

Clinical and molecular diagnosis of pathologic complete response in rectal cancer: an update

INTRODUCTION

The standard of care for locally advanced rectal cancer includes neoadjuvant chemoradiation with subsequent total mesorectal excision. This approach has shown various degrees of response to neoadjuvant chemoradiation (ranging from complete response to further tumor growth), which have substantial prognostic and therapeutic implications. A total regression of the tumor is a predictor of superior oncologic outcomes compared with partial responders and non-responders. Further, this concept has opened the possibility of nonoperative strategies for complete responders and explains the widespread research interest in finding clinical, radiographic, pathologic, and biochemical parameters that allow for identification of these patients. Areas covered: The present review evaluates the most recent efforts in the literature to identify predictors of patients likely to achieve a complete response following neoadjuvant treatment for the management of rectal cancer. This includes clinical predictors of pathologic complete response such as tumor location, size, and stage, molecular predictors such as tumor biology and microRNA, serum biomarkers such as carcinoembryogenic antigen and nomograms. Expert commentary: There has been significant progress in our ability to predict pathological complete response. However, more high-quality research is still needed to use this concept to confidently dictate clinical management.

Potentiating the effects of radiotherapy in rectal cancer: the role of aspirin, statins and metformin as adjuncts to therapy

BACKGROUND

Complete tumour response (pCR) to neo-adjuvant chemo-radiotherapy for rectal cancer is associated with a reduction in local recurrence and improved disease-free and overall survival, but is achieved in only 20-30% of patients. Drug repurposing for anti-cancer treatments is gaining momentum, but the potential of such drugs as adjuncts, to increase tumour response to chemo-radiotherapy in rectal cancer, is only just beginning to be recognised.

METHODS

A systematic literature search was conducted and all studies investigating the use of drugs to enhance response to neo-adjuvant radiation in rectal cancer were included. 2137 studies were identified and following review 12 studies were extracted for full text review, 9 studies were included in the final analysis.

RESULTS

The use of statins or aspirin during neo-adjuvant therapy was associated with a significantly higher rate of tumour downstaging. Statins were identified as a significant predictor of pCR and aspirin users had a greater 5-year progression-free survival and overall survival. Metformin use was associated with a significantly higher overall and disease-free survival, in a subset of diabetic patients.

CONCLUSIONS

Aspirin, metformin and statins are associated with increased downstaging of rectal tumours and thus may have a role as adjuncts to neoadjuvant treatment, highlighting a clear need for prospective randomised controlled trials to determine their true impact on tumour response and overall survival.

Prognosis and value of preoperative radiotherapy in locally advanced rectal signet-ring cell carcinoma

As well known, signet-ring cell carcinoma (SRCC) is a rare histological subtype of colorectal adenocarcinoma, which has been associated with poor prognosis and resistant to non-surgery therapy compared with common adenocarcinoma. In this study, we assessed the effect of preoperative radiotherapy (PRT) for locally advanced rectal SRCC in a large patient group from the Surveillance, Epidemiology, and End Results program (SEER, 1988–2011) database. SRCC was found in 0.9% (n = 622) rectal cancer (RC) patients in our study. In the PRT setting, SRCC had significantly worse cancer-specific survival than mucinous adenocarcinoma and nonmucinous adenocarcinoma patients (log-rank, P < 0.001). In terms of SRCC, stage III RC patients benefited from PRT (log-rank, P < 0.001) while stage II did not (P = 0.095). The multivariate Cox proportional hazard model showed that PRT was an independent benefit factor in stage III rectal SRCC patients (HR, 0.611; 95% CI, 0.407–0.919; P = 0.018). In conclusion, SRCC was an independent predictor of poor prognosis in stage III RC patients, but not in stage II. In the PRT setting of locally advanced RC, SRCC patients had significantly worse prognosis. PRT was an independent prognostic factor associated with improved survival in stage III rectal SRCC.

Pre-treatment platelet counts as a prognostic and predictive factor in stage II and III rectal adenocarcinoma

AIM

To investigate if pre-treatment platelet counts could provide prognostic information in patients with rectal adenocarcinoma that received neo-adjuvant treatment.

METHODS

Platelet number on diagnosis of stage II and III rectal cancer was evaluated in 51 patients receiving neo-adjuvant treatment and for whom there were complete follow-up data on progression and survival, as well as pathologic outcome at the time of surgery. Pathologic responses on the surgical specimen of patients with lower platelet counts (150-300 × 10⁹/L) were compared with these of patients with higher platelet counts (> 300 × 10⁹/L) by the χ² test. Overall and progression free survival Kaplan-Meier curves of the two groups were constructed and compared with the Log-Rank test.

RESULTS

A significant difference was present between the two groups in regards to pathologic response with patients with lower platelet counts being more likely to exhibit a good or complete response to neo-adjuvant treatment than patients with higher platelet counts (P = 0.015). Among other factors evaluated, there was also a significant difference between the carcinoembryonic antigen (CEA) at presentation of patients that exhibited a good or complete response and those that had no response or a minimal to moderate response. Patients with a good or complete response were more likely to present with a CEA of less than 5 μg/L (P = 0.00066). There was no significant difference in overall and progression free survival between the two platelet count groups (Log-Rank tests P = 0.42 and P = 0.35, respectively).

CONCLUSION

In this retrospective analysis of stage II and III rectal cancer patients, platelet counts at the time of diagnosis had prognostic value for neo-adjuvant treatment pathologic response. Pre-treatment CEA also held prognostic value in regards to treatment effect.

Prognostic significance of DSG3 in rectal adenocarcinoma treated with preoperative chemoradiotherapy

AIM

This study aimed to investigate the prognostic significance of DSG3 and its association with response to neoadjuvant concurrent chemoradiotherapy (CCRT) in rectal cancer.

MATERIALS & METHODS

Data mining of a publicly available dataset was performed to find genes associated with CCRT response. Immunohistochemistry was applied to evaluate DSG3 expression. The relationships between DSG3 expression and various clinicopathological parameters and survival were analyzed.

RESULTS

The DSG3 gene was significantly associated with CCRT response. The expression of DSG3 negatively correlated with poorer tumor regression (p < 0.001) and had an independent negative impact on disease-specific survival (p = 0.011), local recurrence-free survival (p = 0.031) and metastasis-free survival (p = 0.029).

CONCLUSION

DSG3 was a key prognostic factor and predictor for CCRT response in rectal cancer patients.