Adjuvant therapy sparing in rectal cancer achieving complete response after chemoradiation

Adjuvant chemotherapy after neoadjuvant chemoradiation and proctectomy improves survival irrespective of pathologic response in rectal adenocarcinoma: a population-based cohort study

BACKGROUND

This study sought to determine whether adjuvant chemotherapy (AC) compared to no AC (noAC) after neoadjuvant chemoradiation (CRT) and resection for rectal adenocarcinoma prolongs survival. Current guidelines from expert groups are conflicting, and data to support administering AC to patients who received neoadjuvant CRT are lacking.

METHODS

A total of 19,867 patients met inclusion/exclusion criteria. Mean age was 58.6 ± 12.0 years, and 12,396 (62.4%) were males. Complete response (CR) was documented in 3801 (19.1%) patients and 8167 (41.1%) received AC. The cohort was stratified into pathological complete (pCR, N = 3801) and incomplete (pIR, N = 16,066) subgroups, and pIR further subcategorized into ypN0 (N = 10,191) and ypN + (N = 5875) subgroups. After propensity score matching, AC was associated with improved OS in the pCR subgroups (mean 139.1 ± 1.9 vs. 134.0 ± 2.2 months; p < 0.001), in pIR ypN0 subgroup (141.6 ± 1.5 vs. 129.9 ± 1.2 months, p < 0.001), and in pIR ypN + subgroup (155.9 ± 5.4 vs. 126.5 ± 7.6 months; p < 0.001).

RESULTS

AC was associated with improved OS in patients who received neoadjuvant CRT followed by proctectomy for clinical stages II and III rectal adenocarcinoma. This effect persisted irrespective of pathological response status.

CONCLUSIONS

AC following neoadjuvant CRT and surgery is associated with improved OS in patients with rectal adenocarcinoma. These findings warrant adoption of AC after neoadjuvant CRT and surgery for clinical stage II and III rectal adenocarcinoma.

Can Elevated Pretreatment Serum Carcinoembryonic Antigen Levels Serve as a Potential Biomarker Guiding Adjuvant Chemotherapy in Rectal Cancer Patients With ypTis-3N0 After Neoadjuvant Radiotherapy and Surgery?

Survival benefit of adjuvant chemotherapy (ACT) remained controversial in patients with stage II/III rectal cancer (RC) who received neoadjuvant therapy and surgery. This study aimed to investigate the guiding role of elevated pretreatment serum carcinoembryonic antigen (CEA) levels for receiving ACT in yield pathological Tis-3N0 (ypTis-3N0) RC patients after neoadjuvant radiotherapy and surgery. Between 2004 and 2015, 10,973 RC patients with ypTis-3N0 who received neoadjuvant radiotherapy and radical surgery were retrospectively analyzed using the Surveillance, Epidemiology, and End Results (SEER) database. Compared with CEA-normal group, elevated-CEA patients had worse 5-year CSS rate (90.1 vs 83.5%). The 5-year CSS rates were 86.3 and 87.4% for ypTis-3N0M0 patients with or without ACT, respectively. Patients receiving ACT had a comparable 5-year CSS rate compared to those who did not regardless of CEA levels in ypTis-3N0M0 RC patients (CEA elevation group: 76.4 vs. 83.5%, P = 0.305; CEA normal group: 90.0 vs. 90.1%, P = 0.943). Intriguingly, ypT3N0M0 RC patients with elevated CEA levels may benefit from ACT (5-year CSS: 69.1 vs. 82.9%, P = 0.045), while those with normal CEA levels did not (5-year CSS: 89.3 vs. 89.3%, P = 0.885). Multivariate Cox analysis demonstrated that ACT tended to be a protective factor in elevated-CEA ypT3N0M0 RC patients (HR = 0.633, 95% CI = 0.344–1.164, P = 0.141), while ACT was not associated with improved CSS in normal-CEA ypT3N0M0 RC patients (HR = 1.035, 95% CI = 0.487–2.202, P = 0.928). Elevated pretreatment serum CEA levels may serve as a promising biomarker guiding ACT in rectal cancer patients with ypT3N0M0.

ACRNaCT trial protocol: efficacy of adjuvant chemotherapy in patients with clinical T3b/T4, N+ rectal Cancer undergoing Neoadjuvant Chemoradiotherapy: a pathology-oriented, prospective, multicenter, randomized, open-label, parallel group clinical trial

BACKGROUND

The CAO/ARO/AIO-94 demonstrated that neoadjuvant chemoradiotherapy (CRT) could decrease the rate of local recurrence rather than distal metastases in advanced rectal cancer. Adjuvant chemotherapy (ACT) can eliminate micrometastasis, and render a better prognosis to rectal cancer. However, adoption of ACT mainly depends on the evidence from colon cancer. Neoadjuvant CRT can lead to tumor shrinkage in a number of patients with advanced rectal cancer. The administration of adjuvant therapy depending on pretreatment clinical stage or postoperative yield pathological (yp) stage remains controversial. At present, the clinical guidelines recommend ACT for patients with stage II/III (ypT3-4 N0 or ypTanyN1-2) rectal cancer following neoadjuvant CRT and surgery. However, the yp stage may influence the guidance of ACT.

METHODS

According to the postoperative pathological stage, the present study was divided into two parts with different study design procedures. Patients will undergo different therapeutic strategies after collecting data related to postoperative pathological stage. For patients with pathologic complete response or yp stage I, the study was designed as a non-inferiority trial to compare the patients' long-term outcomes in observational group and those in treatment group with 5-fluorouracil. For patients at yp stage II or III, the study was designed as a superiority trial to compare the oncological effect of oxaliplatin combined with 5-fluorouracil, in addition to 5-fluorouracil alone in ACT. The primary endpoint is 3-year disease-free survival (DFS). Secondary endpoints are 3-year, 5-year overall survival, 5-year DFS, and the rate of local recurrence and adverse events resulted from chemotherapy and the patients' quality of life postoperatively.

DISCUSSION

The ACRNaCT trial aims to investigate whether observation is not inferior than 5-fluorouracil for pathologic complete response or yp stage I, and indicate whether combined chemotherapy contains superior outcomes than 5-fluorouracil alone for yp stage II or III in patients receiving neoadjuvant CRT and surgery for locally advanced rectal cancer (LARC). This trial is expected to provide individualized adjuvant treatment strategies for LARC patients following neoadjuvant CRT and surgery.

TRIAL REGISTRATION

The trial has been registered in ClinicalTrials.gov on January 30, 2018 (Registration No. NCT03415763), and also, that was registered in Chinese Clinical Trial Registry on November 12, 2018 (Registration No. ChiCTR1800019445).

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.

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.

RBBP6 increases radioresistance and serves as a therapeutic target for preoperative radiotherapy in colorectal cancer

Radiotherapy (RT) can be used as preoperative treatment to downstage initially unresectable locally rectal carcinoma, but radioresistance and recurrence remain significant problems. Retinoblastoma binding protein 6 (RBBP6) has been implicated in the regulation of cell cycle, apoptosis and chemoresistance both in vitro and in vivo. The present study investigated whether the inhibition of RBBP6 expression would improve radiosensitivity in human colorectal cancer cells. After SW620 and HT29 cells were exposed to radiation, the levels of RBBP6 mRNA and protein increased over time in both cells. Moreover, a significant reduction in clonogenic survival and a decrease in cell viability in parallel with an obvious increase in cell apoptosis were demonstrated in irradiated RBBP6‐knockdown cells. Transfection with RBBP6 shRNA improved the levels of G2‐M phase arrest, which blocked the cells in a more radiosensitive period of the cell cycle. These observations indicated that cell cycle and apoptosis mechanisms may be connected with tumor cell survival following radiotherapy. In vivo, the tumor growth rate of nude mice in the RBBP6‐knockdown group was significantly slower than that in other groups. These results indicated that RBBP6 overexpression could resist colorectal cancer cells against radiation by regulating cell cycle and apoptosis pathways, and inhibition of RBBP6 could enhance radiosensitivity of human colorectal cancer.

Personalizing Adjuvant Therapy for Stage II/III Colorectal Cancer

This review focuses on three areas of interest with respect to the treatment of stage II and III colon and rectal cancer, including (1) tailoring adjuvant therapy for the geriatric population, (2) the controversy as to the optimal adjuvant therapy strategy for patients with locoregional rectal cancer and for patients with colorectal resectable metastatic disease, and (3) discussion of the microenvironment, molecular profiling, and the future of adjuvant therapy. It has become evident that age is the strongest predictive factor for receipt of adjuvant chemotherapy, duration of treatment, and risk of treatment-related toxicity. Although incorporating adjuvant chemotherapy for patients who have received neoadjuvant chemoradiation and surgery would appear to be a reasonable strategy to improve survivorship as an extrapolation from stage III colon cancer adjuvant trials, attempts at defining the optimal rectal cancer population that would benefit from adjuvant therapy remain elusive. Similarly, the role of adjuvant chemotherapy for patients after resection of metastatic colorectal cancer has not been clearly defined because of very limited data to provide guidance. An understanding of the biologic hallmarks and drivers of metastatic spread as well as the micrometastatic environment is expected to translate into therapeutic strategies tailored to select patients. The identification of actionable targets in mesenchymal tumors is of major interest.

Adjuvant chemotherapy for ypT0N0M0 rectal cancer following chemoradiotherapy and total mesorectal excision

The management of adenocarcinoma of the rectum is a dynamic field in oncology. The multidisciplinary approach to the management of this disease continues to evolve in each segment of its trimodality treatment. New scheduling regimens and radiosensitizing agents continue to emerge. Although total mesorectal excision continues to be the operation of choice for rectal cancers, what is done before and after surgery continues to evolve to maximize an ideal oncologic outcome with minimal morbidity. The achievement of a pathological complete response [pCR (i.e. ypT0N0)] in a fraction of patients undergoing neoadjuvant chemoradiation poses an interesting management dilemma. The cohort of patients who can achieve a pCR have superior oncologic outcomes compared to nonresponders. The present review addresses the need for adjuvant therapy in patients with a pCR. We discuss the evolution of the role of adjuvant therapy in patients with rectal cancer and the studies addressing the elimination of this strategy in all patients with rectal cancer with a goal of determining the current evidence that might result in the omission of adjuvant therapy for patients with ypT0N0 rectal cancer after chemoradiation and total mesorectal excision.

Is adjuvant chemotherapy necessary for patients with pathological complete response after neoadjuvant chemoradiotherapy and radical surgery in locally advanced rectal cancer? Long-term analysis of 40 ypCR patients at a single center

OBJECTIVES

According to practice guidelines, adjuvant chemotherapy (ACT) is required for all patients with locally advanced rectal cancer who have received neoadjuvant chemoradiotherapy (NCRT) and total mesorectal excision (TME). The objective of this study was to determine whether ACT is necessary for patients achieving pathological complete response (pCR) after NCRT followed by surgery.

METHODS

By retrospectively reviewing a prospectively collected database in our single tertiary care center, 210 patients with locally advanced rectal cancer who underwent NCRT followed by TME were identified between February 2005 and August 2013. All patients achieving ypCR were enrolled in this study, in which who underwent ACT (chemo group) and who did not (non-chemo group) were compared in terms of local recurrence (LR) rate, 5-year disease-free survival (DFS) rate and overall survival (OS) rate.

RESULTS

Forty consecutive patients with ypCR were enrolled, 19 (47.5 %) in chemo group and 21 (52.5 %) in non-chemo group. After a median follow-up of 57 months, five patients developed systemic recurrences, with the 5y-DFS rate of 83.5 %. No LR occurred in the two groups. The 5y-DFS rates for patients in chemo group and non-chemo group was 90.9 and 76.0 %, respectively, showing no statistically significant difference (p = 0.142). Multivariate analysis showed that tumor grade was the only independent prognostic factor for 5y-DFS and 5y-OS.

CONCLUSIONS

Results of this study suggested that it may not be necessary for all rectal cancer patients with ypCR after NCRT and radical surgery to receive ACT. Prospective randomized trials are warranted to further determine the value of ACT for ypCR patients.

Multimodal Rectal Cancer Treatment: In Some Cases, Less May Be More

A series of clinical trials in the last several decades has resulted in the development of multimodality treatment of locally advanced rectal cancer that includes neoadjuvant (preoperative) chemoradiotherapy, total mesorectal excision, and postoperative adjuvant chemoradiotherapy. Owing to this regimen, patients with locally advanced rectal cancer have better survival rates than patients with colon cancer, but at the cost of substantial morbidity and reduced quality of life. The challenge is to identify treatment approaches that maintain or even improve oncologic outcomes while preserving quality of life. We have identified different tumor characteristics that are associated with recurrence and probability of survival for locally advanced rectal cancer. This risk stratification, based on baseline clinical staging and tumor response to chemoradiotherapy, has led us to question whether all patients with locally advanced rectal cancer require every component of the multimodal regimen. In this article, we will review recent evidence that some patients with locally advanced rectal cancer can be spared one or more treatment modalities without compromising long-term oncologic outcomes and while preserving quality of life.