Screening mammography can distort estimated effects in
breast cancer risk models due to associations with other risk factors. Mammography information was available in the Nurses' Health Study from 1988, and 1,815 incident breast
cancers were accrued through 2000 among 55,625 women with risk factor data. Logistic models were fit for screening mammography, and inverse probability weighting was used to adjust parameters in an established
breast cancer risk model. Approximately 80% of women in each 2-year follow-up period had screening mammograms, which were positively associated with history of benign
breast disease, family history of
breast cancer,
hormone therapy, alcohol use, physical activity, multivitamins, and
calcium supplements, and negatively associated with postmenopause, current smoking, and body mass index. Markers of medical attention, including
hypertension, high
cholesterol, and
osteoarthritis, were positively associated, while
cardiovascular disease was negative. Inverse probability weighting led to small changes in effects of benign
breast disease, family history, and
hormone therapy. An apparent reduced risk associated with current smoking in unadjusted models was eliminated after weighting. Thus, several risk factors for
breast cancer and
cancer diagnosis are associated with mammographic screening. Adjustment for screening had some impact on
breast cancer prediction in this cohort, especially for
hormone therapy and smoking.