Biology and Medicine

Abstract

Prognostic Impact of Diabetes Mellitus on Colorectal Cancer

Yoshiko Ota, Soichiro Ishihara, Koji Yasuda, Kazushige Kawai, Keisuke Hata, Hiroaki Nozawa, Hironori Yamaguchi, Eiji Sunami, Joji Kitayama and Toshiaki Watanabe

Background: Diabetes mellitus (DM) is suggested to be associated with colorectal cancer (CRC); however, the direct relationship between DM and CRC has not been proven.

Objective: The aim of this study is to clarify oncological behavior of CRC with DM.

Methods: This study is a retrospective cohort study. We investigated 1216 patients with curatively resected CRC. Clinicopathological factors and prognosis were compared between the patients with and without DM.

Results: DM was observed in 34% of the patients. The patients with DM were significantly older, were predominantly males, had larger tumors, and died more frequently of causes other than CRC than those without DM. While overall survival (OS) was significantly inferior in the patients with DM than in those without (83% vs. 88%, p=0.01), there was no difference in cancer-specific survival (CSS) between the two groups (91% vs. 91%, p=0.6). The examination of survival at each cancer stage showed that CSS of the patients with DM tended to be superior in stage II cancer (97% vs. 93%, p=0.07) and was worse in stage IV cancer (54% vs. 70%, p=0.05).

Conclusions: OS was worse in the CRC patients with DM who more often died of causes other than CRC, and thus, DM did not affect CSS as a whole. However, with the progression of CRC, DM appeared to worsen CSS. It is unclear whether this is attributed to differences in malignancy or in treatment; this should be further examined.