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 University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8655, Japan * Corresponding author: Yoshiko Ota, MD, Department of Surgical Oncology, University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8655, Japan, Tel: +81-3-5800-8653; Fax: +81-3-3811-6822; E-mail: kikkawa-tky@umin.ac.jp Received date: March 18, 2016; Accepted date: April 11, 2016; Published date: April 15, 2016 Copyright: © 2016 Ota Y, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited. Abstract 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. Keywords: Colorectal cancer; Diabetes mellitus; Surgery; Prognosis Introduction Many epidemiological studies have reported a relationship between diabetes mellitus (DM) and cancer, some of which suggested that DM is associated with colorectal cancer (CRC) [1-8]. Some case-control studies revealed that abnormal glucose intolerance or DM is more common among patients with CRC than among controls [1-3], and some cohort studies showed that a history of DM or insulin resistance increases the risk of developing CRC [4-8]. However, most of these studies showed that there is a relationship between DM and the onset of CRC only. Whether DM is directly related to cancer [9,10], whether DM is an indicator of potential factors that alter cancer risk [11-13], or whether the association between DM and cancer is indirect via common risk factors [14-16], remain unclear [17]. Furthermore, prognosis has not been fully examined, with some reports describing short-term postoperative mortality [18-20]. herefore, in this study, we aimed to examine the clinicopathological characteristics and postoperative prognosis of patients with curatively resected CRC and DM and to clarify oncological behavior of CRC with DM. Patients and Methods Patient population his was a retrospective study of 1216 patients who underwent elective and curative surgery for primary CRC in the University of Tokyo Hospital between January 2000 and December 2009. Patients with curatively resected distant metastases were also enrolled. In patients with multiple synchronous CRCs, only the largest lesion was considered. he mean follow-up period from the date of surgery to the date of death or to the last visit to the hospital was 74 ± 39 months. he study was performed with the approval of the ethics committee of the University of Tokyo Hospital. Deinition of diabetes mellitus We used all blood sample data recorded in medical charts of our hospital. In accordance with the Japanese diabetes diagnostic criteria [21], DM was deined as having a fasting blood glucose (FBG) level of 126 mg/dl (7 mmol/L) or higher on at least two occasions or having an FBG level of 126 mg/dl (7 mmol/L) or higher and an hemoglobin A1c (HbA1c) (NGSP) level of 6.5% or higher. Patients whose past data satisied these criteria and those receiving DM treatment were regarded as patients with a diagnosis of DM. Preoperative blood tests were performed without receiving intravenous nutrition within approximately one month before colorectal surgery. Because some patients had a blood sample drawn only once and had only one set of data, a strict diagnosis of DM could not be made for such patients. Ota Y et al., Biol Med (Aligarh) 2016, 8:4 DOI: 10.4172/0974-8369.1000299 Research Article Open Access Biol Med (Aligarh) ISSN:0974-8369 BLM, an open access journal Volume 8 • Issue 4 • 1000299 B i o l o g y a n d M e d i c i n e ISSN: 0974-8369 Biology and Medicine