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.