Prognostic Impact of Histologic Type in Curatively Resected Stage IV Colorectal Cancer: A Japanese Multicenter Retrospective Study.

Abstract

This study aimed to clarify differences in prognostic factors, metastatic features, and recurrence rates between histologic types in patients with stage 4 colorectal cancer (CRC) who had undergone curative resection. The data from 1131 patients with stage 4 colorectal cancer from the databases of referral institutions were analyzed. The patients were divided into two groups according to histologic types as follows: patients with poorly differentiated adenocarcinoma, mucinous adenocarcinoma, or signet-ring cell carcinoma (Por/Muc/Sig) and patients with well-differentiated or moderately differentiated adenocarcinoma (Wel/Mod). Differences in clinicopathologic features, relapse-free survival (RFS) rates, and cancer-specific survival (CSS) rates between the groups were evaluated. Although RFS did not differ between the Por/Muc/Sig and Wel/Mod groups, CSS was significantly shorter in the Por/Muc/Sig group's than in the Wel/Mod group, and survival after recurrence was significantly worse in the Por/Muc/Sig group than in theWel/Mod group. The incidence of peritoneal or local recurrence was significantly higher for the Por/Muc/Sig patients, whereas the resection recurrence rate was 16.4 %. Multivariate analysis suggested that histologic type was an independent prognostic factor for survival after recurrence. The patients with Por/Muc/Sig CRC synchronous metastasis had significantly shorter survival times than the patients with other CRC histologies, even if the metastases were curatively resected.