Prognostic influence of histopathological regression patterns in rectal adenocarcinoma receiving neoadjuvant therapy

Identification of radiologic and clinicopathologic variables associated with tumor regression pattern and distribution of cancer cells after short-course radiotherapy and consolidation chemotherapy in patients with rectal cancer

Background

Knowledge of the pattern of regression and distribution of residual tumor cells may assist in the selection of candidates for rectum-sparing strategies.

Objective

To investigate and identify factors associated with tumor regression pattern and distribution of residual tumor cells.

Methods

We conducted a prospective study of patients with T3/T4 N0/N+ adenocarcinoma of the middle and lower third of the rectum (≤10 cm) treated with radiotherapy (5×5 Gy) followed by 6 cycles of CAPOX chemotherapy. The pattern of tumor regression was classified as fragmented or solid. Microscopic intramural spread was measured. We used a model of distribution of residual tumor cells not yet applied to rectal cancer, defined as follows: type I (luminal), type II (invasive front), type III (concentric), and type IV (random).

Results

Forty patients were included with a median age of 66 years; 23 (57.5%) were men. A fragmented pattern was identified in 18 patients (45.0%), and a solid pattern in 22 (55.0%). Microscopic intramural spread was identified in 25 patients (62.5%), extending from 1 to 18 mm (median, 4 mm). There were 14 cases (35.0%) of microscopic intramural spread ≥10 mm. All cases of fragmented regression pattern, except one, showed microscopic intramural spread. Within the fragmented pattern, microscopic intramural spread was 4-8 mm in 4 cases and ≥10 mm in the remaining cases. All cases of microscopic intramural spread ≥ 10 mm were within the fragmented pattern. Regarding the distribution pattern of residual tumor cells, 11 cases (31.5%) were classified as type I, 14 (40.0%) as type II, 10 (28.5%) as type III, and none as type IV. Carcinoembryonic antigen levels >5 ng/mL, downsizing <50%, residual mucosal abnormality >20 mm, and anatomopathologic lymph node involvement were significantly associated with the occurrence of fragmentation (P<0.05). Having received all 6 cycles of CAPOX chemotherapy and absence of microscopic intramural spread were significantly associated with the type I distribution pattern (P<0.05).

Conclusion

The occurrence of a fragmented regression pattern is common, as is the presence of microscopic intramural spread. We could identify radiologic and clinicopathologic factors associated with the pattern of tumor regression and a type I distribution pattern.

Relevance of shrinkage versus fragmented response patterns in rectal cancer

AIMS

Partial response to neoadjuvant chemoradiotherapy (CRT) presents with one of two main response patterns: shrinkage or fragmentation. This study investigated the relevance of these response patterns in rectal cancer, correlation with other response indicators, and outcome.

METHODS AND RESULTS

The study included a test (n = 197) and a validation cohort (n = 218) of post-CRT patients with rectal adenocarcinoma not otherwise specified and a partial response. Response patterns were scored by two independent observers using a previously developed three-step flowchart. Tumour regression grading (TRG) was established according to both the College of American Pathologists (CAP) and Dworak classifications. In both cohorts, the predominant response pattern was fragmentation (70% and 74%), and the scoring interobserver agreement was excellent (k = 0.85). Patients with a fragmented pattern presented with significantly higher pathological stage (ypTNM II-IV, 78% versus 35%; P < 0.001), less tumour regression with Dworak (P = 0.004), and CAP TRG (P = 0.005) compared to patients with a shrinkage pattern. As a predictor of prognosis, the shrinkage pattern outperformed the TRG classification and stratified patients better in overall (fragmented pattern, hazard ratio [HR] 2.04, 95% confidence interval [CI] 1.19-3.50, P = 0.008) and disease-free survival (DFS; fragmented pattern, HR 2.50, 95% CI 1.23-5.10, P = 0.011) in the combined cohorts. The multivariable regression analyses revealed pathological stage as the only independent predictor of DFS.

CONCLUSIONS

The heterogeneous nature of tumour response following CRT is reflected in fragmentation and shrinkage. In rectal cancer there is a predominance of the fragmented pattern, which is associated with advanced stage and less tumour regression. While not independently associated with survival, these reproducible patterns give insights into the biology of tumour response.

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).

Size and depth of residual tumor after neoadjuvant chemoradiotherapy in rectal cancer - implications for the development of new imaging modalities for response assessment

With the shift towards organ preserving treatment strategies in rectal cancer it has become increasingly important to accurately discriminate between a complete and good clinical response after neoadjuvant chemoradiotherapy (CRT). Standard of care imaging techniques such as CT and MRI are well equipped for initial staging of rectal tumors, but discrimination between a good clinical and complete response remains difficult due to their limited ability to detect small residual vital tumor fragments. To identify new promising imaging techniques that could fill this gap, it is crucial to know the size and invasion depth of residual vital tumor tissue since this determines the requirements with regard to the resolution and imaging depth of potential new optical imaging techniques. We analyzed 198 pathology slides from 30 rectal cancer patients with a Mandard tumor regression grade 2 or 3 after CRT that underwent surgery. For each patient we determined response pattern, size of the largest vital tumor fragment or bulk and the shortest distance from the vital tumor to the luminal surface. The response pattern was shrinkage in 14 patients and fragmentation in 16 patients. For both groups combined, the largest vital tumor fragment per patient was smaller than 1mm for 38% of patients, below 0.2mm for 12% of patients and for one patient as small as 0.06mm. For 29% of patients the vital tumor remnant was present within the first 0.01mm from the luminal surface and for 87% within 0.5mm. Our results explain why it is difficult to differentiate between a good clinical and complete response in rectal cancer patients using endoscopy and MRI, since in many patients submillimeter tumor fragments remain below the luminal surface. To detect residual vital tumor tissue in all patients included in this study a technique with a spatial resolution of 0.06mm and an imaging depth of 8.9mm would have been required. Optical imaging techniques offer the possibility of detecting majority of these cases due to the potential of both high-resolution imaging and enhanced contrast between tissue types. These techniques could thus serve as a complimentary tool to conventional methods for rectal cancer response assessment.

Shrinkage versus fragmentation response in neoadjuvantly treated oesophageal adenocarcinoma: significant prognostic relevance

Aims

No consensus exists on the clinical value of tumour regression grading (TRG) systems for therapy effects of neoadjuvant chemoradiotherapy (nCRT) in oesophageal adenocarcinoma. Existing TRG systems lack standardization and reproducibility, and do not consider the morphological heterogeneity of tumour response. Therefore, we aim to identify morphological tumour regression patterns of oesophageal adenocarcinoma after nCRT and their association with survival.

Methods and results

Patients with oesophageal adenocarcinoma, who underwent nCRT followed by surgery and achieved a partial response to nCRT, were identified from two Dutch upper‐gastrointestinal (GI) centres (2005–18; test cohort). Resection specimens were scored for regression patterns by two independent observers according to a pre‐defined three‐step flowchart. The results were validated in an external cohort (2001–17). In total, 110 patients were included in the test cohort and 115 in the validation cohort. In the test cohort, two major regression patterns were identified: fragmentation (60%) and shrinkage (40%), with an excellent interobserver agreement (κ = 0.87). Here, patients with a fragmented pattern had a significantly higher pathological stage (stages III/IV: 52 versus 16%; P < 0.001), less downstaging (48 versus 91%; P < 0.001), a higher risk of recurrence [risk ratio (RR) = 2.9, 95% confidence interval (CI) = 1.5–5.6] and poorer 5‐year overall survival (30 versus 80% respectively, P = 0.001).

Conclusions

The validation cohort confirmed these findings, although had more advanced cases (case‐stages = III/IV 91 versus 73%, P = 0.005) and a higher prevalence of fragmented‐pattern cases (80 versus 60%, P = 0.002). When combining the cohorts in multivariate analysis, the pattern of response was an independent prognostic factor [hazard ratio (HR) = 1.76, 95% CI = 1.0–3.0]. In conclusion, we established an externally validated, reproducible and clinically relevant classification of tumour response.

Prognostic and staging value of tumor deposits in patients with rectal cancer after neoadjuvant chemoradiotherapy

Background

The presence of tumor deposits (TDs) is only considered in the absence of lymph node metastases (LNMs) in the current TNM staging system. However, the prognostic value of TDs when concomitant with LNM for rectal cancer after neoadjuvant chemoradiotherapy (NCRT) remains unclear. This study aimed to evaluate the prognostic value of TDs and when concomitant with LNMs in rectal cancer after NCRT.

Methods

Patients with rectal cancer who had received NCRT between 2010 and 2016 were obtained from the Surveillance, Epidemiology and End Results (SEER) 18 (year range, 1975–2016) database. Data were extracted on the following: age, sex, race, TNM stage, total LNs harvested, positive LNs, histologic type, perineural invasion, grade, carcinoma embryonic antigen status, TD number, and cancer-specific survival (CSS) rates. The primary objective was to determine the prognostic impact of TDs on CSS. The effect of the addition of TD to the LNM count for a novel N stage was also evaluated. Univariate and multivariate analyses were performed using the Kaplan-Meier method and Cox models.

Results

Of 9,620 patients, 865 (9.0%) had TDs. TD-positive patients showed a worse prognosis than TD-negative patients (HR =2.39, 95% CI: 2.04–2.80, P<0.001), and multivariate analysis showed that the presence of TDs was an independent poor prognostic factor (HR =1.41, 95% CI: 1.19–1.67, P<0.001). Regarding the LN status, TDs were associated with a higher risk of cancer-specific death in the LNM- group (HR =2.43, 95% CI: 1.86–3.18, P<0.001), M1 group (HR =1.51, 95% CI: 1.08–2.10, P<0.001), and ypN1 group (HR =2.08, 95% CI: 1.61–2.70, P<0.001), but not in the ypN2 group (HR =0.97, 95% CI: 0.69–1.36, P=0.84). Patients with concomitant TDs and LNM showed significantly worse survival than those with TDs or LNM alone (5-year CSS: 48.2%, 72.2%, and 67.8%, respectively). The 5-year CSS rates were 86.2%, 77.4%, 65.1%, 53.8%, and 46.5% for the novel N0, N1a, N1b, N2a, and N2b groups, respectively (P<0.05 across all groups). Time dependent receiver operating characteristic curve analysis and decision curve analysis showed that the novel N stage was superior to the current ypN stage.

Conclusions

The presence of TDs is an independent poor prognostic factor for LARC patients after NCRT. The concomitant presence of TDs and LNM indicates a significantly worse survival, and the addition of TD to LNM may help to better prompt appropriate risk stratification.

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”.

Connection and distinction of tumor regression grading systems of gastrointestinal cancer

OBJECTIVES

As the neoadjuvant therapy has been successfully introduced in the treatment of gastrointestinal malignancies, the evaluation of therapeutic effectiveness is becoming increasingly important. Tumor-node-metastasis system has been widely applied. However, this system is mainly based on the location of residual tumor, but does not consider the amount of residual tumor. Tumor regression grading system, a quantitative method to assess the reaction of tumor to neoadjuvant treatment, could be used as a supplement to tumor-node-metastasis system and provide additional information on prognosis. To date, numerous gastrointestinal grading systems have been used in esophageal/esophagogastric junction carcinoma, gastric adenocarcinoma, colorectal cancer, and most of them were considered to associate with clinical outcomes.

MATERIALS AND METHODS

In this review, firstly, we expounded the importance of tumor regression grading systems, and summarized the histopathological changes after neoadjuvant therapy. Secondly, we introduced some commonly used gastrointestinal systems, as well as the relationships and nuance. Finally, we discussed pivotal issues about these systems. In this part, we explained the calculation methods based on grid points and square measures, discussed several factors leading to observer bias, containing the slice number and the grading tier number, and analyzed the factors that might affect clinical significance, covering anatomical location, the selection of survival index, and the tumor type.

RESULTS

Tumor regression grade systems could be divided into two main classifications, the relative amount of fibrosis and residual tumor, and the proportion of residual tumor in the tumor bed. However, the definitions of these systems were still need to be improved.

CONCLUSIONS

The tumor regression grading system is useful in evaluating tumor response to neoadjuvant therapy, but more work is needed to refine and unify the system.

How to measure tumour response in rectal cancer? An explanation of discrepancies and suggestions for improvement

Various methods categorize tumour response after neoadjuvant therapy, including down-staging and tumour regression grading. Response categories allow comparison of different treatments within clinical trials and predict outcome. A reproducible response categorization could identify subgroups with high or low risk for the most appropriate subsequent treatments, like watch and wait. Lack of standardization and interpretation difficulties currently limit the usability of these approaches. In this review we describe these difficulties for the evaluation of chemoradiation in rectal cancer. An alternative approach of tumour response is based on patterns of residual disease, including fragmentation. We summarise the evidence behind this alternative method of response categorisation, which explains a number of very relevant clinical discrepancies. These issues include differences between downstaging and tumour regression, high local regrowth in advanced tumours during watchful waiting procedures, the importance of resection margins, the limited value of post-treatment biopsies and the relatively poor outcome of patients with a near complete pathological response. Recognition of these patterns of response can allow meaningful development of novel biomarkers in the future.

Mucin Pools Following Neoadjuvant Chemoradiotherapy for Rectal Cancer: A Marker of Response or Epiphenomenon?

Neoadjuvant chemoradiotherapy (CRT) is the standard of care for locally advanced rectal cancer. Morphologic changes such as fibrosis, inflammatory infiltrates, and the formation of extracellular mucin pools can be identified in the resection specimen after neoadjuvant CRT. The association of mucin pool formation with clinicopathologic variables and outcomes is unclear. The aim of this study was to meta-analyze all available evidence with regard to mucin pool formation and clinicopathologic outcomes following neoadjuvant CRT for rectal cancer. A comprehensive search for published studies analyzing outcomes between patients who formed mucin pools and patients who did not following neoadjuvant CRT for rectal cancer was performed. A random-effects model was used to combine the data. This study adhered to the recommendations of the MOOSE (Meta-analyses of Observational Studies in Epidemiology) guidelines. Data from 11 studies describing 1947 patients were included. Mucin pool formation was not associated with sex, T stage, N stage, tumor regression, pathologic complete response rate, lymphovascular invasion, perineural invasion, differentiation, margin status, local or distant recurrence, and disease-free or overall survival. Mucin pool formation is not associated with tumor response or downstaging; furthermore, on the basis of these data, it is not associated with local or systemic recurrence rate or survival.

Predictors and Risk Factors of Pathologic Complete Response Following Neoadjuvant Chemoradiotherapy for Rectal Cancer: A Population-Based Analysis

Background: Patients with rectal cancer who achieve pathologic complete response (pCR) after neoadjuvant chemoradiotherapy (nCRT) may have a better prognosis and may be eligible for non-operative management. The aim of this research was to identify variables for predicting pCR in rectal cancer patients after nCRT and to define clinical risk factors for poor outcome after pCR to nCRT and radical resection in rectal cancer patients. Methods: A retrospective review was performed using the Surveillance, Epidemiology, and End Results (SEER) database from 2004 to 2013. Non-metastatic rectal cancer patients who received radical resection after neoadjuvant chemoradiotherapy were included in this study. Multivariate analysis of the association between clinicopathological characteristics and pCR was performed, and a logistic regression model was used to identify independent predictors for pCR. A nomogram based on the multivariate logistics regression was built with decision curve analyses to evaluate the clinical usefulness. Results: A total of 6,555 patients were included in this study. The proportion of patients with pCR was 20.5% (n = 1,342). The nomogram based on multivariate logistic regression analysis showed that clinical T4 and N2 stages were the most significant independent clinical predictors for not achieving pCR, followed by mucinous adenocarcinoma and positive pre-treatment serum CEA results. The 3-year overall survival rate was 92.4% for those with pCR and 88.2% for those without pCR. Among all the pCR patients, mucinous adenocarcinoma patients had the worst survival, with a 3-year overall survival rate of 67.5%, whereas patients with common adenocarcinoma had an overall survival rate of 93.8% (P < 0.001). Univariate and multivariate analyses showed that histology and clinical N2 stage were independent risk factors. Conclusion: Mucinous adenocarcinoma, positive pre-treatment serum CEA results, and clinical T4 and N2 stages may impart difficulty for patients to achieve pCR. Mucinous adenocarcinoma and clinical N2 stage might be indicative of a prognostically unfavorable biological tumor profile with a greater propensity for local or distant recurrence and decreased survival.