Objective: To examine the impact of mammography screening on treatment options received by a cohort of older breast cancer patients.
Setting and population: We studied 718 newly diagnosed breast cancer patients, 67 years and over, diagnosed with TNM Stage I and II disease between 1995 and 1997 at 29 hospitals in five regions.
Methods: Data were collected from patients, surgeons, and medical records. A breast cancer diagnosis was considered to have been by screening mammography if so reported by both patient and medical records. Bivariate and logistic regression were used to identify predictors of a women having her cancer detected by screening mammography and the relationships between mode of detection, stage of disease at diagnosis, and local treatment.
Results: Women with high school or greater education were 1.75 times (95%, CI 1.11-2.75) more likely to have their cancers diagnosed by screening mammography than women who had not completed high school, controlling for other factors. Screening found earlier stage disease: 96% of women with mammographically diagnosed cancer had T1 lesions, compared to 81% of women diagnosed by other means (p = 0.001). Women with mammography detected lesions were more likely to have ductal cancer, and to be referred to radiation oncologists more than women diagnosed by other means. Controlling for stage and histology, screening remained associated with a higher likelihood of receiving breast conserving surgery (BCS) with radiation (RT) (OR 1.56, 95%, CI 1.10-2.22) than other local therapies.
Conclusions: Beyond the impact on stage, ductal cancers were more likely to be diagnosed by screening. Mammographically detected lesions were associated with referrals to radiation oncologists and higher rates of BCS and RT. Research is needed to explain the residual independent effects of mammography screening on breast cancer treatment.