Is routine use of adjuvant chemotherapy for rectal cancer with complete pathological response justified?

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.

Predicting survival in locally advanced rectal cancer with effective chemoradiotherapy response

BACKGROUND

Locally advanced rectal cancer patients often display favorable responses and favorable oncologic outcomes. Due to the low recurrence rate, there is scarcity of studies investigating the prognostic factors influencing their survival. Therefore, our study sought to assess the prognostic factors associated with survival in rectal cancer patients who achieved either a pathologic complete response or a pathologic stage I after neoadjuvant chemoradiotherapy combined with radical resection.

METHODS

In this retrospective study, we analyzed data from cohort of 1394 patients diagnosed with locally advanced rectal cancer who underwent neoadjuvant chemoradiotherapy combined with total mesorectal excision from January 2008 to April 2017. Finally, we selected 474 (34.2 %) who exhibited either a pathologic complete response or attained pathologic stage I following the treatment. Subsequently, we analyzed the prognostic factors influencing disease-free and overall survival.

RESULTS

A total of 161 (34 %) achieved a pathologic complete response. Our analysis revealed that circumferential resection margin and the administration of adjuvant chemotherapy were prognostic factors for disease-free survival (p = 0.011, p = 0.022). Furthermore, factors influencing overall survival included the clinical N stage and administration of adjuvant chemotherapy (p = 0.035, p = 0.015).

CONCLUSION

In conclusion, the circumferential resection margin, clinical N stage, and administration of adjuvant chemotherapy were prognostic factors for survival in patients showing good response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer. For patients with a positive circumferential resection margin and clinical N (+) stage, intensive follow-up might be needed to achieve favorable oncologic outcomes. Also, we recommend considering adjuvant chemotherapy as a beneficial treatment approach for these patients.

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.

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.

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.

Oncologic benefit of adjuvant chemotherapy for locally advanced rectal cancer after neoadjuvant chemoradiotherapy and curative surgery with selective lateral pelvic lymph node dissection: An international retrospective cohort study

INTRODUCTION

Intensive local treatment comprising total mesorectal excision (TME) with selective lateral pelvic lymph node dissection (LPND) after neoadjuvant chemoradiotherapy (CRT) for locally advanced rectal cancer (LARC) has received attention among clinicians treating rectal cancer. It remains unclear whether adjuvant chemotherapy (ACT) after intensive local treatment is beneficial for these patients. We evaluated the oncologic benefit of ACT for patients with LARC who received intensive local treatment.

MATERIALS AND METHODS

This international multicentre retrospective cohort study included 737 patients treated in Japan and Korea between 2010 and 2017. The effectiveness of ACT on recurrence-free survival (RFS) was evaluated using univariable and multivariable Cox proportional hazards models, with subgroup analyses to identify subpopulations potentially benefiting from ACT.

RESULTS

The median follow-up was 49 months; the 5-year RFS and local recurrence rates for the entire cohort were 72.1% and 4.9%, respectively; 514 patients (69.7%) received adjuvant chemotherapy, without an oncologic benefit (hazard ratio, 1.14; 95% confidence interval [CI]: 0.79-1.68) demonstrated in the multivariable Cox regression analysis. In subgroup analyses, the distributions of the 95% CI in patients aged ≥70 years and those with ypStage 0 tended to place a disproportionate emphasis that favoured the non-ACT treatment strategy.

CONCLUSION

Despite achieving good local control with intensive local treatment strategy, the effectiveness of ACT for the LARC patients with CRT followed by TME with selective LPND was not proved. Elderly patients and those with ypStage0 may not receive benefit from ACT after CRT and TME ± LPND.

Evaluating the benefit of adjuvant chemotherapy in patients with ypT0–1 rectal cancer treated with preoperative chemoradiotherapy

BACKGROUND

Adjuvant chemotherapy (ACTx) is recommended in rectal cancer patients after preoperative chemoradiotherapy (PCRT), but its efficacy in patients in the early post-surgical stage who have a favorable prognosis is controversial.

AIM

To evaluate the long-term survival benefit of ACTx in patients with ypT0–1 rectal cancer after PCRT and surgical resection.

METHODS

We identified rectal cancer patients who underwent PCRT followed by surgical resection at the Asan Medical Center from 2005 to 2014. Patients with ypT0–1 disease and those who received ACTx were included. The 5-year overall survival (OS) and 5-year recurrence-free survival (RFS) were analyzed according to the status of the ACTx.

RESULTS

Of 520 included patients, 413 received ACTx (ACTx group) and 107 did not (no ACTx group). No significant difference was observed in 5-year RFS (ACTx group, 87.9% vs no ACTx group, 91.4%, P = 0.457) and 5-year OS (ACTx group, 90.5% vs no ACTx group, 86.2%, P = 0.304) between the groups. cT stage was associated with RFS and OS in multivariate analysis [hazard ratio (HR): 2.57, 95% confidence interval (CI): 1.07–6.16, P = 0.04 and HR: 2.27, 95%CI: 1.09–4.74, P = 0.03, respectively]. Furthermore, ypN stage was associated with RFS and OS (HR: 4.74, 95%CI: 2.39–9.42, P < 0.00 and HR: 4.33, 95%CI: 2.20–8.53, P < 0.00, respectively), but only in the radical resection group.

CONCLUSION

Oncological outcomes of patients with ypT0–1 rectal cancer who received ACTx after PCRT showed no improvement, regardless of the radicality of resection. Further trials are needed to evaluate the efficacy of ACTx in these group of patients.

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.

Downstaged ypT0-2N0 rectal cancer after neoadjuvant chemoradiation therapy may not need adjuvant chemotherapy: a retrospective cohort study

PURPOSE

Current guidelines suggest that adjuvant chemotherapy (AC) be administered to all locally advanced (clinically T3-4 or N-positivity) rectal cancer patients undergoing neoadjuvant chemoradiotherapy (nCRT) and radical surgical resection regardless of the final pathological staging (yp staging). This study aimed to evaluate the necessity of AC for ypT0-2N0 rectal cancer.

METHODS

Patients with ypT0-2N0 rectal cancer, who received nCRT and radical surgical resection, were recruited retrospectively at a university hospital. The main outcome was to evaluate the 5-year overall survival (OS) and disease-free survival (DFS) between ypT0-2N0 rectal cancer patients with AC and those without AC. We also identified potential independent prognostic factors associated with poor outcomes.

RESULTS

One hundred and ten ypT0-2N0 rectal cancer patients (ypT0: n = 6; ypT1: n = 44; ypT2: n = 60) were followed up for a median of 60 months. No significant difference was observed in DFS and 5-year OS between patients with AC and those without AC. The risk of recurrence was associated with the postoperative pathological staging (0% with ypT0, 2.4% with ypT1, and 10% with ypT2). In the multivariate analysis, retrieval of < 12 lymph nodes was an independent favorable prognostic factor, which correlated with a higher OS (HR: 2.263; 95% CI: 1.093-4.687, P = 0.028). Intra-tumor lymphovascular and perineural invasion were poor prognostic markers for shorter DFS (HR: 5.940; 95% CI: 1.150-30.696, P = 0.033).

CONCLUSION

Postoperative AC is not required for patients with ypT0-2N0 rectal cancer downstaged by nCRT, especially in those without poor prognostic factors.

Oncologic effects of adjuvant chemotherapy in patients with ypT0-2N0 rectal cancer after neoadjuvant chemoradiotherapy and curative surgery: a meta-analysis

Purpose

The role of adjuvant chemotherapy for patients with ypT0–2N0 rectal cancer following neoadjuvant chemoradiotherapy (nCRT) and curative surgery is uncertain. We performed a meta-analysis using selected studies to compare adjuvant chemotherapy with observation for this cohort of patients.

Methods

PubMed, Embase, and the Cochrane Library were searched. Data were pooled, and overall effect size was calculated using random effect models. Outcome measures were 5-year overall survival (OS), disease-free survival (DFS), local, and distant recurrence.

Results

We included 17 nonrandomized studies for qualitative analysis and 16 nonrandomized studies that examined 4,747 patients for the meta-analysis. In analysis of patients with ypT0N0 rectal cancer, adjuvant chemotherapy had no significant effect on OS (odds ratio [OR], 1.53; 95% confidence interval [CI], 0.86–2.72; I² = 27%), DFS (OR, 1.22; 95% CI, 0.61–2.42; I² = 5%), local recurrence (OR, 0.78; 95% CI, 0.08–7.37; I² = 0%), and distant recurrence (OR, 1.04; 95% CI, 0.41–2.62; I² = 0%). In analysis of patients with ypT1–2N0 rectal cancer, adjuvant chemotherapy also had no significant effect on OS (OR, 2.15; 95% CI, 0.59–7.80; I² = 26%), DFS (OR, 1.66; 95% CI, 0.35–7.85; I² = 44%), local recurrence (OR, 2.56; 95% CI, 0.72–9.13; I² = 0%), and distant recurrence (OR, 1.15; 95% CI, 0.23–5.87; I² = 0%).

Conclusion

Adjuvant chemotherapy may have no oncologic benefits in patients with ypT0–2N0 rectal cancer after nCRT and radical surgery. Routine use of adjuvant chemotherapy for those patients may be avoided.

Prognostic impact of acellular mucin pools towards the patients with locally advanced rectal cancer achieving pathological complete response after preoperative chemoradiotherapy

BACKGROUND

To date, the prognostic significance of acellular mucin pools in tumors from patients with locally advanced rectal cancer (LARC) undergoing preoperative chemoradiotherapy (CRT) and subsequently obtaining pathological complete response (pCR) has not been well determined. Our current study aimed to explore the prognostic impact on these patients of acellular mucin pools.

METHODS

We collected clinical data from 117 consecutive LARC patients who achieved pCR after preoperative CRT and then underwent radical resection. Two groups of patients were generated, according to the presence or absence of acellular mucin pools. The 5-year disease-free survival (DFS) and overall survival (OS) rates were compared between the two groups of patients.

RESULTS

A total of 27 (23.1%) patients presented with acellular mucin pools. At a median follow-up period of 64 months, patients with acellular mucin pool showed a 5-year DFS rate (96.3% versus 83.7%, p = 0.110) and 5-year OS rate (100% versus 87.5%, p = 0.054) statistically similar to those of patients without acellular mucin pools. In univariable and multivariable Cox regression analyses, the presence of acellular mucin pools was not determined as an independent risk factor for DFS [hazard ratio (HR): 0.222; 95% confidence interval (CI): 0.029-1.864; p = 0.145] or OS (HR: 0.033; 95% CI: 0.000-9.620; p = 0.238).

CONCLUSIONS

Acellular mucin pools had no significant prognostic impact on LARC patients showing pCR after preoperative CRT.

The Role of Adjuvant Chemotherapy in ypT0N0 Rectal Adenocarcinoma

BACKGROUND

In patients who develop a complete pathologic response (ypT0N0) following neoadjuvant chemoradiation, the benefits of postoperative chemotherapy remain uncertain. This study aims to determine whether treatment with adjuvant chemotherapy in ypT0N0 patients affects short- and long-term outcomes.

METHODS

From January 2000 to December 2015, 992 patients at our institution underwent surgery for rectal adenocarcinoma following treatment with neoadjuvant chemoradiation. A complete pathologic response was noted in 96 (9.7%) patients. Adjuvant chemotherapy was administered to 60 (62.5%) patients. We reviewed clinical and pathological records and compared outcomes in ypT0N0 patients who received adjuvant chemotherapy to those who did not.

RESULTS

The mean age of patients who received adjuvant chemotherapy was 55.6 ± 11.5 years, compared to 62.1 ± 11.7 years for those who did not (p = 0.008). Among the two groups, mean follow-up time after surgery was 5.3 ± 4.1 years for the adjuvant group and 8.3 ± 5.5 years for the non-adjuvant cohort (p = 0.003). The 1, 3, and 5-year survival rates were 100.0%, 97.7%, and 92.1% for patients who received adjuvant chemotherapy and 97.2%, 94.1%, and 90.7% for those who did not (p = 0.382). In a subanalysis of patients with available follow-up information, we observed 3/53 (5.7%) disease recurrences in patients who received adjuvant chemotherapy, compared to 2/18 (11.1%) in those who were not treated postoperatively (p = 0.456).

CONCLUSION

In patients with ypT0N0 rectal adenocarcinoma, we found equivalent survival and recurrence outcomes. Further study will be necessary to determine the importance of adjuvant chemotherapy following ypT0N0 resection.

Association Between Adjuvant Chemotherapy and Overall Survival in Patients With Rectal Cancer and Pathological Complete Response After Neoadjuvant Chemotherapy and Resection

Importance

Although American guidelines recommend use of adjuvant chemotherapy in patients with locally advanced rectal cancer, individuals who achieve a pathological complete response (pCR) following neoadjuvant chemoradiotherapy are less likely to receive adjuvant treatment than incomplete responders. The association and resection of adjuvant chemotherapy with survival in patients with pCR is unclear.

Objective

To determine whether patients with locally advanced rectal cancer who achieve pCR after neoadjuvant chemoradiation therapy and resection benefit from the administration of adjuvant chemotherapy.

Design, Setting, and Participants

This retrospective propensity score-matched cohort study identified patients with locally advanced rectal cancer from the National Cancer Database from 2006 through 2012. We selected patients with nonmetastatic invasive rectal cancer who achieved pCR after neoadjuvant chemoradiation therapy and resection.

Exposures

We matched patients who received adjuvant chemotherapy to patients who did not receive adjuvant treatment in a 1:1 ratio. We separately matched subgroups of patients with node-positive disease before treatment and node-negative disease before treatment to investigate for effect modification by pretreatment nodal status.

Main Outcome and Measures

We compared overall survival between groups using Kaplan-Meier survival methods and Cox proportional hazards models.

Results

We identified 2455 patients (mean age, 59.5 years; 59.8% men) with rectal cancer with pCR after neoadjuvant chemoradiation therapy and resection. We matched 667 patients with pCR who received adjuvant chemotherapy and at least 8 weeks of follow-up after surgery to patients with pCR who did not receive adjuvant treatment. Over a median follow-up of 3.1 years (interquartile range, 1.94-4.40 years), patients treated with adjuvant chemotherapy demonstrated better overall survival than those who did not receive adjuvant treatment (hazard ratio, 0.44; 95% CI, 0.28-0.70). When stratified by pretreatment nodal status, only those patients with pretreatment node-positive disease exhibited improved overall survival with administration of adjuvant chemotherapy (hazard ratio, 0.24; 95% CI, 0.10-0.58).

Conclusions and Relevance

The administration of adjuvant chemotherapy in patients with rectal cancer with pCR is associated with improved overall survival, particularly in patients with pretreatment node-positive disease. Although this study suggests a beneficial effect of adjuvant treatment on survival in patients with pCR, these results are limited by the presence of potential unmeasured confounding in this nonrandomized study.

Association of Adjuvant Chemotherapy With Overall Survival in Patients With Rectal Cancer and Pathologic Complete Response Following Neoadjuvant Chemotherapy and Resection

Importance

Adjuvant chemotherapy (AC) in patients with rectal cancer with pathologic complete response following neoadjuvant chemoradiotherapy (nCRT) and resection is recommended by treatment guidelines. However, its role in this setting is equivocal because data supporting benefits are lacking.

Objective

To compare the overall survival (OS) between AC and postoperative observation (OB) in patients with rectal cancer with pathologic complete response following nCRT and resection.

Design, Setting, and Participants

We identified a cohort of patients with rectal cancer and a complete pathological response (ypT0N0) after nCRT in the National Cancer Database between 2006 and 2012. Patients who received AC were compared with OB patients by propensity score matching. Overall survival was compared using the stratified log-rank test and stratified Cox regression model. The outcomes after AC vs OB were also evaluated in patient subgroups. The data analysis was completed in June 2017.

Exposures

Adjuvant chemotherapy and OB.

Main Outcomes and Measures

Overall survival.

Results

We identified 2764 patients (mean [SD] age, 60.0 [12.3] years; 40% female) with clinical stage II or III resected adenocarcinoma of the rectum who had received nCRT and were complete responders (ypT0N0M0). Of this cohort, 741 patients in the AC group were matched by propensity score to 741 patients who underwent OB. The AC cohort had better OS compared with the OB cohort (hazard ratio, 0.50; 95% CI, 0.32-0.79). The 1-, 3-, and 5-year OS rates were 99.7%, 97.1%, and 94.7% for the AC group and 99.2%, 93.6%, and 88.4% for the OB group (P = .005). In subgroup analysis, patients with clinical stage T3/T4 and node-positive disease benefited most from AC (hazard ratio, 0.47; 95% CI, 0.25-0.91).

Conclusions and Relevance

Adjuvant chemotherapy was associated with improved OS in patients with pathologic complete response after nCRT for resected locally advanced rectal cancer. This study supports the use of AC in this setting where there is currently paucity of data.

Adjuvant chemotherapy in rectal cancer patients who achieved a pathological complete response after preoperative chemoradiotherapy: a systematic review and meta-analysis

This study evaluated the prognostic impact of ACT in patients who achieved a pathological complete response (pCR). Articles published from January 1990 to September 2018 were searched in EMBASE, PubMed, Ovid, Web of Science, and Cochrane Library. Hazard ratios (HRs) and 95% confidence intervals (CIs) of overall survival (OS) were extracted. Thirteen observational studies were included. There were four National Cancer Database studies with overlapping study periods, thus individual pooled analyses of four different datasets were conducted (n = 3,182, 3,330, 3,575, and 4,739 for pooled analysis sets including Dossa et al., Polanco et al., Xu et al., and Shahab et al., respectively). Although a trend toward improved OS with ACT was observed, statistical significance was not proven (P = 0.09, P = 0.03, P = 0.12, and P = 0.10, respectively). When we performed a stratified analysis comparing the results from single institution and multicenter studies, there was no significant prognostic benefit of ACT. Publication bias was not observed. Routine use of ACT in patients with a pCR could not be warranted from the present meta-analysis. Further study of individual patient data from randomized trials is needed to clarify the role of ACT.

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

Background

It is recommended postoperative adjuvant chemotherapy for all rectal cancers undergoing neo-chemoradiotherapy regardless of the final yield pathology. However, the role of adjuvant chemotherapy in pathological complete response (pCR) remains controversial. We aimed to identify the necessarily of adjuvant chemotherapy in pCR.

Methods

Consecutive patients with pCR in Fudan University Shanghai Cancer Center (FUSCC) were enrolled. Meanwhile, a pooled analysis of individual patient with pCR was performed from PubMed and Embase databases for validation.

Results

A total of 171 patients form FUSCC were identified to achieve pCR with up to almost 10 years follow-up. Among them, those receiving adjuvant chemotherapy had no survival benefits compared to those without adjuvant chemotherapy (log-rank test = 0.17, P = 0.676). The 5y-DFS rates for patients in chemo group and no-chemo group was 87.5 and 88.8%, respectively, showing no significant difference (p = 0.854). No matter chemotherapy regimens, T stage, EMVI and CRM status varied, the results remained consistent. Meantime, the COX model did not demonstrate adjuvant chemotherapy as the independent risk factor for OS and DFS. Additionally, among 18 systemic recurrences in all, the rate of relapse surged rapidly on the 12 months and rose up to peak in the 36th months. In order to validate these results, nine controlled trials involving 5491 patients with pCR were included in this pooled-analysis. For both 5-year overall survival and disease-free survival, the pooling data did not produce a statistically significant effect in cases of adjuvant chemotherapy performed (RR = 0.79 and RR = 0.95, respectively, all p > 0.05).

Conclusion

This study suggested that rectal cancer patients with pCR did not benefit from adjuvant chemotherapy and we recommended that achievement of pCR require more prolonged close follow care in case of distant metastasis.

Is adjuvant chemotherapy necessary for locally advanced rectal cancer patients with pathological complete response after neoadjuvant chemoradiotherapy and radical surgery? A systematic review and meta-analysis

PURPOSE

Current clinical guidelines recommended the routine use of adjuvant chemotherapy for locally advanced rectal cancer (LARC) patients. However, the effects of adjuvant chemotherapy in patients with pathological complete response (pCR) after neoadjuvant chemoradiotherapy and radical surgery showed discrepancies in different investigations.

METHODS

A systematic review and meta-analysis were conducted using PubMed, Embase and Web of Science databases. All original comparative studies published in English that were related to adjuvant versus non-adjuvant chemotherapy for LARC patients with pCR were included.

RESULTS

A total of 6 studies based on 18 centres or databases involving 2948 rectal cancer patients with pCR (adjuvant group = 1324, non-adjuvant group = 1624) were included in our overall analysis. Based on our meta-analysis, LARC patients with pCR who received adjuvant chemotherapy showed a significantly improved overall survival (OS) when compared to patients with observation (HR = 0.65, 95% CI = 0.46-0.90, P = 0.01). In addition, investigations focused on this issue based on the National Cancer Database (NCDB) were systematically reviewed in our current study. Evidence from all three analyses demonstrated that LARC patients with clinical nodal positive disease that achieved pCR might benefit the most from additional adjuvant chemotherapy.

CONCLUSION

Our meta-analysis indicated that adjuvant chemotherapy is associated with improved OS in LARC patients with pCR after neoadjuvant chemoradiotherapy and radical surgery.

Is adjuvant chemotherapy necessary for patients with ypT0-2N0 rectal cancer treated with neoadjuvant chemoradiotherapy and curative surgery?

Background and objective

The benefit from adjuvant chemotherapy for patients treated with neoadjuvant chemoradiotherapy (NCRT) and curative surgery remains controversial, particularly among those responding well to NCRT. This retrospective study aimed to clarify the benefits of adjuvant chemotherapy in terms of the oncological outcomes of patients with ypT0–2N0 rectal cancer after NCRT and curative surgery.

Methods

All patients with ypT0–2N0 rectal cancer after NCRT and curative resection between 2005 and 2014 were examined. The oncological outcomes between patients treated with adjuvant chemotherapy and those without any chemotherapy were compared.

Results

The clinicopathological characteristics of 110 patients were reviewed in this study; one patient was excluded due to lack of follow-up. Of the 109 patients included, 58 (53.2%) underwent adjuvant chemotherapy (chemo group), whereas the remaining 51 (46.8%) did not receive any chemotherapy (non-chemo group). After a median follow-up of 50 months, there were no significant differences in the 5-year overall survival (OS) or recurrence-free survival (RFS) rates between the groups (OS: 92.1 vs 86.3%, P = 0.375; RFS: 80.9 vs 74.7%, P = 0.534). Subgroup analysis also demonstrated no significant differences in 5-year OS and RFS rates between patients with ypT0N0 rectal cancer (P = 0.712 and P = 0.599, respectively) and those with ypT1–2N0 disease (P = 0.255 and P = 0.278, respectively).

Conclusions

These results indicate that patients with ypT0–2N0 rectal cancer after NCRT followed by curative surgery may not derive significant benefit from adjuvant chemotherapy. However, further prospective randomized trials, with larger sample sizes, are warranted to confirm this conclusion.

Oxaliplatin-containing adjuvant chemotherapy improves the survival of locally advanced rectal cancer patients with pathological complete response after pre-operative chemoradiotherapy

Background

The necessity for adjuvant chemotherapy (ACT) in locally advanced rectal cancer (LARC) patients who achieve pathological complete response (pCR) after pre-operative chemoradiotherapy (CRT) is still not identified. We aimed to investigate the therapeutic value of ACT in these patients.

Methods

Clinical data were retrospectively collected from 105 consecutive LARC patients who achieved pCR after pre-operative CRT and underwent radical tumor resection between December 2008 and April 2014 in a comprehensive cancer center. Perioperative chemotherapy (CT) was administered by combining oxaliplatin with capecitabine (XELOX regimen). Disease-free survival (DFS) and overall survival (OS) rates of patients with or without ACT were compared.

Results

Eighty-three (79.0%) patients received ACT and 22 (21.0%) did not. With a median follow-up of 49 months, the ACT group had a significantly higher 3-year DFS rate (92.8 vs 86.4%, p = 0.029) and 3-year OS rate (95.1 vs 86.1%, p = 0.026) than the non-ACT group. In multivariable analyses, the presence of ACT was an independent prognostic factor for DFS (hazard ratio [HR]: 0.271; 95% confidence interval (CI): 0.080–0.916; p = 0.036) but not for OS. This benefit was more obvious in patients younger than 60 years via subgroup analysis (adjusted HR: 0.106; 95% CI: 0.019–0.606; p = 0.012).

Conclusions

Oxaliplatin-containing ACT may confer survival benefits to patients with pCR, particularly younger patients. However, the routine use of ACT in patients with pCR needs further validation.