Diabetes, Abnormal Glucose, Dyslipidemia, Hypertension, and Risk of Inflammatory and Other Breast Cancer.

Background: Obesity has been associated with substantially higher risk of inflammatory breast cancer (IBC) than other breast cancer. Here, we assess whether comorbidities of obesity, namely diabetes, abnormal glucose, dyslipidemia, and hypertension, are differentially related to risk of IBC and other breast cancers by tumor stage at diagnosis (localized/regional/distant/unstaged).
Methods: We used linked SEER-Medicare data, with female breast cancer cases ages 66+ years identified by SEER registries (years 1992-2011). We divided first breast cancers into IBC (N = 2,306), locally advanced non-IBC (LABC; N = 10,347), and other (N = 197,276). We selected female controls (N = 200,000) from a stratified 5% random sample of Medicare recipients alive and breast cancer free. We assessed exposures until 12 months before diagnosis/selection using Medicare claims data. We estimated odds ratios (OR) and 99.9% confidence intervals (CI) using unconditional logistic regression.
Results: Diabetes was associated with increased risk of distant IBC (98.5% of IBC cases; OR 1.44; 99.9% CI 1.21-1.71), distant (OR 1.24; 99.9% CI, 1.09-1.40) and regional (OR 1.29 (99.9% CI, 1.14-1.45) LABC, and distant (OR 1.23; 99.9% CI, 1.10-1.39) and unstaged (OR 1.32; 99.9% CI, 1.18-1.47) other breast cancers. Dyslipidemia was associated with reduced risk of IBC (OR 0.80; 95% CI, 0.67-0.94) and other breast cancers except localized disease. Results were similar by tumor estrogen receptor status. Abnormal glucose levels and hypertension had little association with risk of any tumor type.Conclusions: Associations with diabetes and dyslipidemia were similar for distant stage IBC and other advanced tumors.Impact: If confirmed, such findings could suggest avenues for prevention. Cancer Epidemiol Biomarkers Prev; 26(6); 862-8. ©2017 AACR. ©2017 American Association for Cancer Research.