Association of the severity of diabetes-related complications with stage of breast cancer at diagnosis among elderly women with pre-existing diabetes

Purpose: This study assessed the association between the severity of diabetes complications using diabetes complications severity index (DCSI) and stage of breast cancer (BC) at diagnosis among elderly women with pre-existing diabetes and incident BC. Methods: Using Surveillance, Epidemiology and End Results-Medicare data, we identified women with incident BC during 2004–2011 and pre-existing diabetes (N = 7729). Chi-square tests were used to test for group differences in stage of BC at diagnosis. Multinomial logistic regression was used to examine the associations between the severity of diabetes complications and stage of BC at diagnosis. Results: Overall, women with a DCSI = 2 and a DCSI ≥ 3 were more likely to be diagnosed at advanced stages as compared to those with no diabetes complications. In full adjusted association (after adding BC screening to the analysis model), the severity of diabetes complications was no longer an independent predictor of advanced stages at diagnosis. However, women with a DCSI = 2 were 26% more likely to be diagnosed at stage I (versus stage 0) of BC at diagnosis as compared to those without diabetes complications (OR 1.26, 95% CI 1.03–1.53). Conclusion: The increased likelihood of having advanced-stage BC at diagnosis associated with severity of diabetes-related complications appears to be mediated by lower rates of breast cancer screening among elderly women with pre-existing diabetes complications. Therefore, reducing disparity in receiving breast cancer screening among elderly women with diabetes may reduce the risk of advanced-stage breast cancer diagnosis.