Neoadjuvant-treated N2 rectal cancer linked to PCR failure

Orlando – Clinical N2 disease may be a negative predictor of pathological complete response (PCR) after neoadjuvant chemoradiotherapy for rectal cancer, an analysis of a large, multicenter database has suggested.

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In multivariate regression, pretreatment N2 stage was the only variable significantly associated with failure of achieving pathologic complete response, according to Ebram Salama, MD, of Sir Mortimer B. Davis Jewish General Hospital at McGill University, Montreal.

“We should be reconsidering putting these patients in watch-and-wait protocols,” Dr. Salama said in an oral abstract presentation at the American College of Surgeons Quality and Safety Conference.

The analysis included 369 elective cases of cT2-4 N0-2 rectal cancer that were treated with neoadjuvant chemoradiotherapy during 2016 from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) proctectomy-specific database.

Of those cases, 53 (14.4%) achieved PCR, a proportion consistent with what has been reported previously in medical literature, Dr. Salama noted during his presentation.

The multivariate analysis revealed that pretreatment N2 stage was a negative predictor of PCR with an odds ratio of 0.18 (95% confidence interval, 0.04-0.82; P = .026), according to presented data.

By contrast, Dr. Salama said, there were no significant associations between response and other variables, including pretreatment N1 stage, pretreatment T stage, tumor location, gender, or body mass index.

Dr. Salama acknowledged limitations of this retrospective study, including a lack of data on other variables of interest, such as carcinoembryonic antigen, tumor size, imaging characteristics, molecular markers, and the time interval between chemoradiotherapy and surgery.

“We obviously need more data to evaluate other predictive factors in achieving a complete pathological response,” he said, adding that it’s also unclear whether the results of the present study could be generalized to institutions not participating in ACS NSQIP.

Dr. Salama presented the research on behalf of Nathalie Wong-Chong, MD, also of McGill University. He had no conflicts of interest to report for his presentation.