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

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.

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

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

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.

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.