The association between medical history and breast cancer risk: A nationwide population-based case-control study using claim data

[[abstract]]Introduction: It is suggested that chronic disease may be associated with increased cancer risk due to common risk factors, treatments to the prior conditions, or other unknown mechanisms. We evaluated the associations between prior medical conditions and subsequent breast cancer risk using the claim data from the Taiwan National Health Insurance (NHI) program. Material and Method: A matched case-control study was conducted using the NHI 1,000,000 random sample dataset. A list of medical conditions based on literature review was retrieved for each case and control. The odds ratios (OR) and 95% confidence intervals (CI) of the association between medical conditions and breast cancer risk were estimated using conditional logistic regression and adjusted for occupation and number of breast cancer screening. The associations were estimated for younger (