Adjuvant chemotherapy for rectal cancer with complete pathological response (pCR) may not be necessary: a pooled analysis of 5491 patients

Impact of adjuvant chemotherapy on survival after pathological complete response in rectal cancer: a meta-analysis of 31,558 patients

BACKGROUND

Locally advanced rectal cancer (LARC) typically involves neoadjuvant chemoradiotherapy (nCRT) followed by surgery (total mesorectal excision, TME). While achieving a complete pathological response (pCR) is a strong indicator of a positive prognosis, the specific benefits of adjuvant chemotherapy after pCR remain unclear. To address this knowledge gap, we conducted a systematic review and meta-analysis to assess the potential advantages of adjuvant therapy in patients who achieve pCR.

METHODS

In this study, we searched Medline, Embase, and Web of Science databases for relevant research. We focused on binary outcomes, analyzing them using odds ratios (ORs) with 95% confidence intervals (CIs). To account for potential variability between studies, all endpoints were analyzed with DerSimonian and Laird random-effects models. We assessed heterogeneity using the I2 statistic and employed the R statistical software (version 4.2.3) for all analyses.

RESULTS

Thirty-four studies, comprising 31,558 patients, were included. The outcomes demonstrated a significant difference favoring the AC group in terms of overall survival (OS) (HR 0.75; 95% CI 0.60-0.94; p = 0.015; I2 = 0%), and OS in 5 years (OR 1.65; 95% CI 1.21-2.24; p = 0.001; I2 = 39%). There was no significant difference between the groups for disease-free survival (DFS) (HR 0.94; 95% CI 0.76-1.17; p = 0.61; I2 = 17%), DFS in 5 years (OR 1.19; 95% CI 0.82-1.74; p = 0.36; I2 = 43%), recurrence-free survival (RFS) (HR 1.10; 95% CI 0.87-1.40; p = 0.39; I2 = 0%), and relapse-free survival (OR 1.08; 95% CI 0.78-1.51; p = 0.62; I2 = 0%).

CONCLUSION

This systematic review and meta-analysis found a significant difference in favor of the ACT group in terms of survival after pCR. Therefore, the administration of this treatment as adjuvant therapy should be encouraged in clinical practice.

Effect of adjuvant chemotherapy on the oncological outcome of rectal cancer patients with pathological complete response

BACKGROUND

Locally advanced rectal cancer is typically treated using a combination of neoadjuvant chemoradiotherapy and total mesorectal resection. While achieving pathological complete response following neoadjuvant chemoradiotherapy has been recognized as a positive prognostic factor in oncology, the necessity of adjuvant chemotherapy for locally advanced rectal cancer patients with pathological complete response after surgery remains uncertain. The objective of this meta-analysis was to examine the impact of adjuvant chemotherapy on the oncological outcomes of rectal cancer patients who attain pathological complete response after neoadjuvant chemoradiotherapy.

METHODS

This meta-analysis followed the guidelines outlined in the preferred reporting items for systematic review and meta-analysis (PRISMA). The Web of Science, PubMed, and Cochrane Library databases were systematically searched to identify relevant literature.

RESULTS

A total of 34 retrospective studies, including 9 studies from the NCBD database, involving 31,558 patients with pathological complete response rectal cancer, were included in the meta-analysis. The included studies were published between 2008 and 2023. The pooled analysis demonstrated that adjuvant chemotherapy significantly improved overall survival (HR = 0.803, 95% CI 0.678-0.952, P = 0.011), and no heterogeneity was observed (I2 = 0%). Locally advanced rectal cancer patients with pathological complete response who underwent adjuvant chemotherapy exhibited a higher 5-year overall survival rate compared to those who did not receive adjuvant chemotherapy (OR = 1.605, 95% CI 1.183-2.177, P = 0.002). However, the analysis also revealed that postoperative ACT did not lead to improvements in disease-free survival and recurrence-free survival within the same patient population. Subgroup analysis indicated that pathological complete response patients with clinical stage T3/T4, lymph node positivity, and younger than 70 years of age may benefit from adjuvant chemotherapy in terms of overall survival.

CONCLUSIONS

The findings of this meta-analysis suggest that adjuvant chemotherapy has a beneficial effect on improving overall survival among rectal cancer patients with pathological complete response. However, no such association was observed in terms of disease-free survival and recurrence-free survival.

Predicting the risk of distant metastasis in patients with locally advanced rectal cancer using model based on pre-treatment T2WI-based radiomic features plus postoperative pathological stage

Objective

To assess the prognostic value of a model based on pre-treatment T2WI-based radiomic features and postoperative pathological staging in patients with locally advanced rectal cancer who have undergone neoadjuvant chemoradiotherapy.

Methods

Radiomic features were derived from T2WI, and a radiomic signature (RS) was established and validated for the prediction of distant metastases (DM). Subsequently, we designed and validated a nomogram model that combined the radiomic signature and postoperative pathological staging for enhanced DM prediction. Performance measures such as the concordance index (C-index) and area under the curve (AUC) were computed to assess the predictive accuracy of the models.

Results

A total of 260 patients participated in this study, of whom 197 (75.8%) were male, and the mean age was 57.2 years with a standard deviation of 11.2 years. 15 radiomic features were selected to define the radiomic signature. Patients with a high-risk radiomic signature demonstrated significantly shorter distant metastasis-free survival (DMFS) in both the development and validation cohorts. A nomogram, incorporating the radiomic signature, pathological T stage, and N stage, achieved an area under the curve (AUC) value of 0.72 (95% CI, 0.60-0.83) in the development cohort and 0.83 (95% CI, 0.73-0.92) in the validation cohort.

Conclusion

A radiomic signature derived from T2WI-based radiomic features can effectively distinguish patients with varying risks of DM. Furthermore, a nomogram integrating the radiomic signature and postoperative pathological stage proves to be a robust predictor of DMFS.

MicroRNAs as Predictive Biomarkers in Patients with Colorectal Cancer Receiving Chemotherapy or Chemoradiotherapy: A Narrative Literature Review

Colorectal cancer (CRC) is one of the most common malignancies and is associated with high mortality rates worldwide. The underlying mechanism of tumorigenesis in CRC is complex, involving genetic, lifestyle-related, and environmental factors. Although radical resection with adjuvant FOLFOX (5-fluorouracil, leucovorin, and oxaliplatin) chemotherapy and neoadjuvant chemoradiotherapy have remained mainstays of treatment for patients with stage III CRC and locally advanced rectal cancer, respectively, the oncological outcomes of these treatments are often unsatisfactory. To improve patients' chances of survival, researchers are actively searching for new biomarkers to facilitate the development of more effective treatment strategies for CRC and metastatic CRC (mCRC). MicroRNAs (miRs), small, single-stranded, noncoding RNAs, can post-transcriptionally regulate mRNA translation and trigger mRNA degradation. Recent studies have documented aberrant miR levels in patients with CRC or mCRC, and some miRs are reportedly associated with chemoresistance or radioresistance in CRC. Herein, we present a narrative review of the literature on the roles of oncogenic miRs (oncomiRs) and tumor suppressor miRs (anti-oncomiRs), some of which can be used to predict the responses of patients with CRC to chemotherapy or chemoradiotherapy. Moreover, miRs may serve as potential therapeutic targets because their functions can be manipulated using synthetic antagonists and miR mimics.

Clinical significance of adjuvant chemotherapy for pathological complete response rectal cancer patients with acellular mucin pools after neoadjuvant chemoradiotherapy

Background

Approximately 15-30% of locally advanced rectal cancer (LARC) patients achieved pathological complete response (pCR) after neoadjuvant chemoradiotherapy (CRT) and total mesorectal excision, but the clinical significance of adjuvant chemotherapy (ACT) for pCR patients remains unclear.

Objectives

To determine whether LARC pCR patients can benefit from the administration of ACT.

Design

Single center retrospective study.

Methods

This study retrospectively included 280 LARC patients who achieved pCR after CRT and surgery from 2011 to 2019. The information of patients was recorded. Main outcome measures included 5-year disease-free survival (DFS) and 5-year overall survival. Subgroup analysis was conducted on whether pCR patients with acellular mucin pools received ACT or not.

Results

A total of 74/280 (26.4%) patients were identified with acellular mucin pools. Disease recurrence occurred in 38/280 (13.6%) patients, and in the subgroup of patients with acellular mucin pools, 15/74 (20.3%) patients developed distant metastases. The existence of acellular mucin pools was associated with worse DFS (79.7% versus 88.8%, P = 0.037). Among pCR patients with acellular mucin pools, 9/25 (36.0%) of non-ACT patients occurred recurrence, and ACT was beneficial for improving DFS (hazard ratio: 0.245; 95% confidence interval: 0.084-0.719; P = 0.010).

Conclusions

The existence of acellular mucin pools may represent a sign of invasive tumor biology, which indicated a negative prognosis. ACT can improve the prognosis of patient with acellular mucin pools, so ACT should be considered for them.

miRNA-148a Enhances the Treatment Response of Patients with Rectal Cancer to Chemoradiation and Promotes Apoptosis by Directly Targeting c-Met

Patients with locally advanced rectal cancer (LARC) who achieve a pathological complete response (pCR) to neoadjuvant chemoradiotherapy (NACRT) have an excellent prognosis, but only approximately 30% of patients achieve pCR. Therefore, identifying predictors of pCR is imperative. We employed a microRNA (miRNA) microarray to compare the miRNA profiles of patients with LARC who achieved pCR (pCR group, n = 5) with those who did not (non-pCR group, n = 5). The validation set confirmed that miRNA-148a was overexpressed in the pCR group (n = 11) compared with the non-pCR group (n = 40). Cell proliferation and clonogenic assays revealed that miRNA-148a overexpression radio-sensitized cancer cells and inhibited cellular proliferation, before and after irradiation (p < 0.01). Apoptosis assays demonstrated that miRNA-148a enhanced apoptosis before and after irradiation. Reporter assays revealed that c-Met was the direct target gene of miRNA-148a. An in vivo study indicated that miRNA-148a enhanced the irradiation-induced suppression of xenograft tumor growth (p < 0.01). miRNA-148a may be a biomarker of pCR following NACRT and can promote apoptosis and inhibit proliferation in CRC cells by directly targeting c-Met in vitro and enhancing tumor response to irradiation in vivo.

Pretreatment Neutrophil-to-Lymphocyte Ratio Associated with Tumor Recurrence and Survival in Patients Achieving a Pathological Complete Response Following Neoadjuvant Chemoradiotherapy for Rectal Cancer

Simple Summary

Patients with locally advanced rectal cancer who achieve a pathological complete response to neoadjuvant chemoradiotherapy have been associated with excellent long-term prognosis. However, approximately 9% to 12% of patients with a pathological complete response have been reported to experience tumor recurrence and thereby experience poor outcomes. Identifying predictors of recurrence in patients with a pathological complete response is crucial for precise medicine. The neutrophil-to-lymphocyte ratio is a widely available biomarker of systemic inflammation and affects colorectal prognosis. The study aimed to assess the association between neutrophil-to-lymphocyte ratio and oncological outcomes in rectal cancer patients exhibiting a pCR. We found that a pretreatment high neutrophil-to-lymphocyte ratio (≥3.2) was an independent predictor of reduced overall survival and disease-free survival in patients with locally advanced rectal cancer who achieved a pathological complete response to neoadjuvant chemoradiotherapy. Our findings demonstrate that the neutrophil-to-lymphocyte ratio helps identify patients with a pathological complete response who are at high risk of tumor relapse and might facilitate patient selection for precise medicine.

Abstract

The clinical influence of the neutrophil-to-lymphocyte ratio (NLR) in predicting outcomes in patients with locally advanced rectal cancer (LARC) who achieve a pathological complete response (pCR) to neoadjuvant chemoradiotherapy (NACRT) has seldom been investigated. We retrospectively recruited 102 patients with LARC who achieved a pCR to NACRT and the association of NLR status with survival and tumor recurrence in the patients was analyzed. Thirteen patients (12.7%) developed tumor recurrence. A high NLR (≥3.2) was significantly associated with tumor recurrence (p = 0.039). The 5-year OS rates in patients with a low NLR and patients with a high NLR were 95.1% and 77.7%, respectively (p = 0.014); the 5-year DFS rates in patients with low NLR and patients with a high NLR were 90.6% and 71.3%, respectively (p = 0.031). The Cox proportional hazards model indicated that an NLR of ≥3.2 was an independent poor prognostic factor for DFS (hazard ratio [HR] = 3.12, 95% confidence interval [CI] = 1.06–9.46, p = 0.048) and OS (HR = 6.96, 95% CI = 1.53–35.51, p = 0.013). A pretreatment high NLR (≥3.2) was a promising predictor of reduced OS and DFS in patients with LARC who achieved a pCR to NACRT.

Current evidence regarding the role of adjuvant chemotherapy in rectal cancer patients with pathologic complete response after neoadjuvant chemoradiotherapy: a systematic review and meta-analysis

PURPOSE

The aim of this meta-analysis was to investigate the role of adjuvant chemotherapy (AC) in rectal cancer patients with pathologic complete response (pCR) after neoadjuvant chemoradiotherapy (nCRT) and curative resection.

METHODS

This study was completed in accordance to the PRISMA guidelines and the Cochrane Handbook for Systematic Reviews of Interventions. The electronic scholar databases (Medline, Web of Science, Scopus) were screened for eligible articles. The level of evidence (LoE) was assessed using the GRADE methodology.

RESULTS

Overall, 23 non-randomized studies and 17,406 patients were included in the present meta-analysis. Pooled comparisons confirmed that AC improved overall survival (HR: 0.68, p=0.0003), but not disease-free (p=0.22) and recurrence-free survival (p=0.39). However, the LoE for all outcomes was characterized as "very low," due to the absence of RCTs.

CONCLUSIONS

Considering the study limitations and the lack of randomized studies, further high-quality RCTs are required to confirm the findings of our study.

Nomogram to Predict Distant Metastasis Probability for Pathological Complete Response Rectal Cancer Patients After Neoadjuvant Chemoradiotherapy

Purpose

This study aimed to predict the risks of distant metastasis (DM) of locally advanced rectal cancer (LARC) patients with pathological complete response (pCR) after neoadjuvant chemoradiotherapy (NACRT) and total mesorectal excision (TME), and to find the association between adjuvant chemotherapy (ACT) and their survival outcomes.

Methods and Materials

A total of 242 patients with LARC achieving pCR after NACRT were enrolled in this retrospective study. We developed a nomogram model using logistic regression analyses for predicting risk of DM. The model performance was evaluated by the concordance index and calibration curve. Survival was determined using Kaplan–Meier survival curve.

Results

Age, pre-operative CEA, pre-treatment CEA and distance of tumor to anal verge were identified as significantly associated variables that could be enrolled in the model to predict the risk of DM for pCR patients. The nomogram we created had a bootstrapped-concordance index of 0.731 (95% CI = 0.627 to 0.834) and was well calibrated. The high risk group was more likely to develop DM than low risk group (total score) (95% CI = 1.439 to 6.493, P = 0.0036). The 1-year, 3-year, and 5-year distant metastasis-free survival (DMFS) for the low and high risk groups (total score ≤ 90 vs > 90) was 97.8%, 94.2%, 94.2% and 91.3%, 83.4%, 81.8%, respectively (P = 0.0036). DM occurred within 1 and 2 years after TME surgery was 33.3% and 55.6% for the low risk group, and 47.3% and 84.2% for the high risk group. The value of ACT was assessed among the whole cohort, patients with cT_3-4, with cN₊ or with either DM risk group, but no significant difference was observed concerning DMFS whether ACT was given or not (all P > 0.05). Active treatment after DM was more beneficial than palliative treatment (P < 0.001).

Conclusion

The nomogram model, including age, pre-operative CEA, pre-treatment CEA and distance to anal verge, predicted the probability of DM among LARC patients achieving pCR after NACRT. The effects of ACT were not seen in different subgroups, while closer clinical follow-up may have greater contribution to pCR patients in the first 2 years, especially for patients with relatively higher risk to develop DM. It is suggested that timely active treatment can bring survival benefit for pCR patients developing DM after NACRT.

MRI-defined high-risk rectal cancer patients: outcome comparison between neoadjuvant chemoradiotherapy plus TME and TME plus adjuvant chemotherapy or TME alone

OBJECTIVE

The goal of this study was to investigate whether neoadjuvant chemoradiotherapy (NCRT) plus total mesorectal excision (TME) would improve the outcome of patients with MRI-defined high-risk rectal cancer compared with TME plus adjuvant chemotherapy (ACT) or TME alone.

METHODS

We retrospectively enrolled 362 patients with MRI-defined high-risk rectal cancer who were treated with NCRT plus TME, TME plus ACT, or TME alone between January 2008 and August 2018. Cases with a high-risk tumor stage, positive extramural venous invasion, or mesorectal fascia involvement on baseline MRI were considered cases of high-risk rectal cancer. We matched patients treated with NCRT plus TME to patients treated with TME plus ACT and to those treated with TME alone. Kaplan-Meier curves were used to compare local recurrence (LR), disease-free survival (DFS), and overall survival (OS) rates.

RESULTS

The cumulative 3 year LR rate in the matched NCRT plus TME group was more favorable than in the TME plus ACT group (0% vs 5.1%; p = 0.037; n = 98) and in the TME alone group (0% vs 11.5%; p = 0.016; n = 61). Patients who received NCRT plus TME demonstrated better cumulative 3 year DFS rates than patients treated with TME plus ACT (85.7% vs 65.3%; p = 0.009) or with TME alone (86.9% vs 68.9%; p = 0.046). No difference in OS was observed among the groups.

CONCLUSION

NCRT may improve DFS and LR rates in patients with MRI-defined high-risk rectal cancer when compared with TME plus ACT or TME alone.

ADVANCES IN KNOWLEDGE

This study illustrated the specific benefit of NCRT on the outcome measures of MRI-defined high-risk rectal cancer compared with TME plus ACT or TME alone, which was not clearly clarified in previous studies enrolling all patients with Stage II/III rectal cancer.

Adjuvant chemotherapy in rectal cancer: state of the art and future perspectives

PURPOSE OF REVIEW

The value of adjuvant chemotherapy in rectal cancer is controversial with opinions varying from 'not be used' since randomized trials have not shown significant gains to 'be used as in colon cancer' as the need is the same and colon and rectal cancers are quite similar. This review will look upon data critically and with open eyes.

RECENT FINDINGS

With the exception of one randomized phase II trial (ADORE) revealing a significant gain in disease-free survival using one more effective regimen (mFOLFOX) than bolus 5-fluorouracil leucovorin, no new data have been presented. However, bringing up aspects in previous trials, either considered irrelevant for the present situation or overall negative, of what adjuvant treatment can achieve, a small reduction (hazard ratio about 0.8) in the risk of recurrence is present. This reduction is not fundamentally different from that in colon cancer considering that adjuvant treatment for rectal cancer cannot be initiated as rapidly as it can after a colon cancer diagnosis.

SUMMARY

Adjuvant chemotherapy after rectal cancer surgery reduces recurrence risks but the benefit is limited and for most patients not clinically relevant. Neoadjuvant therapy can be more effective but results from randomized trials are not yet available.

Adjuvant Chemotherapy in Elderly Colorectal Cancer Patients

The value of adjuvant chemotherapy in elderly patients has been the subject of many overviews, with opinions varying from “not effective”, since randomized trials have not been performed, to “as effective as in young individuals”, based upon many retrospective analyses of randomized trials that have included patients of all ages. In the absence of randomized trials performed specifically with elderly patients, retrospective analyses demonstrate that the influence on the time to tumour recurrence (TTR) may be the same as in young individuals, but that endpoints that include death for any reason, such as recurrence-free survival (RFS), disease-free survival (DFS), and overall survival (OS), are poorer in the elderly. This is particularly true if oxaliplatin has been part of the treatment. The need for adjuvant chemotherapy after colorectal cancer surgery in elderly patients is basically the same as that in younger patients. The reduction in recurrence risks may be similar, provided the chosen treatment is tolerated but survival gains are less. Adding oxaliplatin to a fluoropyrimidine is probably not beneficial in individuals above a biological age of approximately 70 years. If an oxaliplatin combination is administered to elderly patients, three months of therapy is in all probability the most realistic goal.

Prognostic Significance of Neoadjuvant Rectal Score and Indication for Postoperative Adjuvant Therapy in Rectal Cancer Patients After Neoadjuvant Chemoradiotherapy

BACKGROUND/AIM

Neoadjuvant chemoradiotherapy (CRT) is a standard treatment for patients with clinical Stage II/III rectal cancer. However, the benefit of postoperative adjuvant chemotherapy for patients after neoadjuvant CRT is uncertain. Recently, neoadjuvant rectal (NAR) score was suggested as an independent prognostic factor for patients with rectal cancer after neoadjuvant CRT. The aim of this study was to examine the prognostic significance of NAR score in rectal cancer patients who underwent neoadjuvant CRT followed by surgery, and to investigate which patients may benefit from postoperative adjuvant therapy.

PATIENTS AND METHODS

A total of 72 patients who underwent neoadjuvant CRT followed by R0 resection for clinical stage II /III rectal cancer were evaluated. The correlation between NAR score, various clinicopathological factors and disease recurrence were evaluated.

RESULTS

Disease recurrence was significantly more often observed in patients with incomplete neoadjuvant CRT, tumor regression grade (TRG) 3-4, and high NAR score. Multivariate analysis revealed that NAR score was an independent predictor of disease recurrence.

CONCLUSION

NAR score may be one of the predictive markers for disease recurrence in patients who underwent neoadjuvant CRT followed by surgery for rectal cancer. Patients with a low NAR score may benefit form postoperative adjuvant chemotherapy.

Rectal cancer patients with downstaging after neoadjuvant chemoradiotherapy and radical resection do not benefit from adjuvant chemotherapy

BACKGROUND

Whether adjuvant chemotherapy is beneficial for rectal cancer patients who respond well to neoadjuvant chemoradiotherapy (NCRT) and undergo radical resection is controversial. This study aimed to assess the effect of adjuvant chemotherapy on the oncological outcomes of ypT0-2N0 rectal cancer patients after NCRT and radical resection, and identify the prognostic factors.

METHODS

The clinical and pathological data of rectal cancer patients with ypT0-2N0 who underwent NCRT and radical resection between January, 2010 and June, 2018 were collected and retrospectively analyzed. The oncological outcomes of the chemotherapy (chemo) group and the non-chemotherapy (non-chemo) group were compared. Multivariate analysis, using a Cox proportional hazard model, was performed to identify independent predictors of oncological outcome.

RESULTS

Of the 121 rectal cancer patients enrolled, 90 patients received postoperative adjuvant chemotherapy with no fewer than 3 cycles (the chemo group), and the other 31 patients with fewer than 3 cycles (the non-chemo group). There was no significant difference in the 5-year disease-free survival (DFS) or overall survival (OS) rates between the two groups (DFS: 79.1% vs. 82.9%, P=0.442; OS: 87.5% vs. 78.2%, P=0.667). cT4 is an independent risk factor for OS (HR =4.227, 95% CI: 1.128-15.838, P=0.02) and DFS (HR =4.878, 95% CI: 1.752-13.578). Preoperative consolidation chemotherapy with Capeox or FOLFOX after NCRT significantly improved the DFS rate (HR =0.212, 95% CI: 0.058-0.776, P=0.019).

CONCLUSIONS

Rectal cancer patients with ypT0-2N0 who underwent NCRT and radical resection did not benefit significantly from postoperative adjuvant chemotherapy. For these patients, cT4 was an independent risk factor for OS and DFS. Preoperative consolidation chemotherapy with Capeox or FOLFOX after NCRT can significantly improve DFS.