Usefulness of Carcinoembryonic Antigen Doubling Time in Prognosis Prediction after Curative Resection of Locally Recurrent Rectal Cancer: A Retrospective Study.

INTRODUCTION: Given that doubling time is an indicator of tumor growth, we assessed the usefulness of carcinoembryonic antigen doubling time (CEA-DT) in prognosis prediction after curative resection for locally recurrent rectal cancer. METHODS: During January 1986-December 2016, 33 patients with locally recurrent rectal cancer who underwent curative resection at our hospital were retrospectively reviewed. The primary endpoint was the 3-year recurrence-free survival (RFS) rate. The Kaplan-Meier method was used to compare RFS rates and evaluate univariate and multivariate analyses for factors associated with oncologic outcomes, including CEA-DT. CEA-DT was classified into 2 groups: the short and long CEA-DT groups. RESULTS: The 3-year overall survival and RFS rates were 62.6% and 42.4%, respectively. In multivariate analyses, CEA-DT was an independent risk factor for poor RFS. The 3-year RFS rate was significantly better in the long CEA-DT group than in the short CEA-DT group (58.8% vs. 25.0%, p = 0.0063). CONCLUSION: CEA-DT is a useful prognostic factor that can be assessed before surgery for locally recurrent rectal cancer. Long CEA-DT may indicate a favorable prognosis. Contrarily, short CEA-DT is associated with poor prognosis; therefore, further treatment intervention is necessary for patients with short CEA-DT.