Diabetes alone should not be a reason for withholding adjuvant chemotherapy for stage III colon cancer.

Background: With increasing prevalence of diabetes mellitus and colon cancer, the number of patients suffering from both diseases is growing, and physicians are being faced with complicated treatment decisions.

Objective: To investigate the association between diabetes and treatment/course of stage III colon cancer and the association between colon cancer and course of diabetes.

Materials And Methods: Additional information was collected from the medical records of all patients with both stage III colon cancer and diabetes (=201) and a random sample of stage III colon cancer patients without diabetes (=206) in the area of the population-based Eindhoven Cancer Registry (1998-2007).

Results: Colon cancer patients without diabetes were more likely to receive adjuvant chemotherapy compared with diabetic colon cancer patients (OR 1.8; 95% CI 1.2-2.7). After adjustment for age, this difference was borderline significant (OR 1.6; 95% CI 1.0-2.6). Diabetic patients did not have: significantly more side-effects from surgery or adjuvant chemotherapy; more recurrence from colon cancer; significantly shorter time interval until recurrence; or a poorer disease-free survival or overall survival. Age and withholding of adjuvant chemotherapy were most predictive of all-cause mortality. After colon cancer diagnosis, the dose of antiglycaemic medications was increased in 22% of diabetic patients, resulting in significantly lower glycaemic indexes than before colon cancer diagnosis.

Conclusions: Since diabetic patients did not have more side-effects of adjuvant chemotherapy, and adjuvant chemotherapy had a positive effect on survival for both patients with and without diabetes, diabetes alone should not be a reason for withholding adjuvant chemotherapy. Journal of Comorbidity 2011;1:19-27.