Abstract
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.
Highlights
Colorectal cancer is the third leading cause of cancer death worldwide [1, 2]
No significant differences were found in age, gender, marital status or race between the pathologic complete response (pCR) and non-pCR groups, but there were differences in histology (P < 0.001), pre-treatment serum CEA results (P = 0.006), clinical T stage (P < 0.001) and N stage (P < 0.001)
Our logistic regression analysis more convincingly identifies mucinous adenocarcinoma, positive pre-treatment serum CEA, and clinical T4 and N2 stages as independent clinical predictors for not achieving pCR. These results are in line with the studies mentioned above and offer additional variables that can help identify those patients who are most likely to respond to treatment, and these findings suggest which clinicopathological factors may be used for predicting pCR
Summary
Colorectal cancer is the third leading cause of cancer death worldwide [1, 2]. Recent studies suggest that 1.2 million new patients are diagnosed annually worldwide, among whom approximately half a million would die of this disease [3]. Some rectal cancer patients who received nCRT achieve a pathologic complete response (pCR), which is always associated with a better outcome than that of patients who had residual tumor after nCRT. More and more research is focused on the “watchful waiting” approach as an alternative to radical resection, which means that those who achieved clinical complete response (cCR) following nCRT are monitored closely instead of receiving surgery [4, 8, 9]. 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
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
