Evaluation of Screening Interval and Mastectomy Rates among Rural U.S. Women with Newly Diagnosed Breast Cancer.

6542 Background: Mammography screening reduces breast cancer mortality, but there is ongoing controversy over optimal target population and interval. We sought to explore the association between screening interval and type of surgery among a population of insured rural U.S. women. Methods: Using claims data, we identified women ages 40 to 65 insured by the National Rural Electric Cooperative Association with a new diagnosis of breast cancer between 2000 and 2012. We characterized screening intervals based on mammoraphy claims prior to diagnosis. Mammography within 3 months of diagnosis was viewed as the index mammogram and we then evaluated prior screening. Mammograms within 14 months were characterized as annual, 26 months biennial, and greater than 26 months less than biennial. We evaluated the correlation between screening interval on type of surgery; mastectomy or breast conservation. We also evaluated correlation between screening interval and mastectomy plus radiation as an indicator of more intensive local therapy and possible proxy for more advanced stage of disease. Results: We identified 517 women with newly diagnosed invasive breast cancer. Two hundred twenty (42%) women were screened annually, 117 (22%) biennially, and 180 (35%) less than biennially. Overall, 120 women received mastectomy, 397 breast conserving surgery, and 59 mastectomy plus radiation therapy. Mastectomy rates were significantly lower for annual screening vs. less than biennial (17% vs. 29%, p = 0.006), but not biennial screening (24%). Mastectomy plus radiation rates were also significantly lower for annual vs. less than biennial screening (7% vs. 17%, p = 0.001), but not biennial (11%). Overall, 26% of women were age 40 to 49 at the time of diagnosis and 40% had undergone annual mammography, 15% biennial, and 45% less than biennial. Despite small numbers, the difference in mastectomy rate between annual and biennial screening among young women was significant (15% vs. 40%, p = 0.02). Conclusions: Annual mammograpy screening may improve surgical options and lower treatment intensity for women diagnosed with breast cancer. These potential benefits should be considered when discussing screening preferences with patients.