Pathologic Complete Response Rates After Neoadjuvant Treatment in Rectal Cancer: An Analysis of the National Cancer Database

Abstract

Background: Pathologic complete response (pCR) of rectal cancer following neoadjuvant therapy is associated with decreased local recurrence and increased overall survival. This study utilizes a national dataset to identify predictors of pCR in patients with rectal cancer.

Methods: The National Cancer Database was queried for patients with nonmetastatic rectal cancer (2004-2014) who underwent neoadjuvant therapy and surgical resection. Unadjusted associations were assessed using rank-sum tests and χ ² tests where appropriate. Backward elimination and forward selection multivariable logistic regression models were created to determine the relationship of annual surgical volume with pCR rate, adjusting for preoperative characteristics and radiation-surgery interval. Statistical tests were two-sided, with a significance level of p ≤ 0.05. Analyses were performed using SAS version 9.4.

Results: A total of 27,532 patients from 1179 participating hospitals met the inclusion criteria. Generalized linear mixed models demonstrated that the odds of achieving pCR was independently associated with more recent diagnosis, female sex, private insurance, lower grade, lower clinical T classification, lower clinical N classification, increasing interval between the end of radiation and surgery, and treatment at higher-volume institutions.

Conclusions: pCR was associated with favorable tumor factors, insurance status, time between radiation and surgery, and institutional volume. It is not clear what is driving the higher rates of pCR at high-volume institutions. Research targeted at understanding processes that are associated with pCR in high-volume institutions is needed so that similar results can be achieved across the spectrum of facilities caring for patients in this population.