Watch and Wait?—Elevated Pretreatment CEA Is Associated with Decreased Pathological Complete Response in Rectal Cancer

Introduction: Between 10 and 30 % of rectal cancer patients experience pathological complete response after neoadjuvant treatment. However, physiological factors predicting which patients will experience tumor response are largely unknown. Previous single-institution studies have suggested an association between elevated pretreatment carcinoembryonic antigen and decreased pathological complete response. Methods: Clinical stage II–III rectal cancer patients undergoing neoadjuvant chemoradiotherapy and surgical resection were selected from the 2006–2011 National Cancer Data Base. Multivariable analysis was used to examine the association between elevated pretreatment carcinoembryonic antigen and pathological complete response, pathological tumor regression, tumor downstaging, and overall survival. Results: Of the 18,113 patients meeting the inclusion criteria, 47 % had elevated pretreatment carcinoembryonic antigen and 13 % experienced pathological compete response. Elevated pretreatment carcinoembryonic antigen was independently associated with decreased pathological complete response (OR = 0.65, 95 % CI = 0.52–0.77, p < 0.001), pathological tumor regression (OR = 0.74, 95 % CI = 0.67–0.70, p < 0.001), tumor downstaging (OR = 0.77, 95 % CI = 0.63–0.92, p < 0.001), and overall survival (HR = 1.45, 95 % CI = 1.34–1.58, p < 0.001). Conclusion: Rectal cancer patients with elevated pretreatment carcinoembryonic antigen are less likely to experience pathological complete response, pathological tumor regression, and tumor downstaging after neoadjuvant treatment and experience decreased survival. These patients may not be suitable candidates for an observational “watch-and-wait” strategy. Future prospective studies should investigate the relationships between CEA levels, neoadjuvant treatment response, recurrence, and survival.