All-Cause Mortality Is Decreased in Women Undergoing Annual Mammography Before Breast Cancer Diagnosis

OBJECTIVE. The value of annual mammography remains an area of debate because of concerns regarding risk versus benefit. The potential for harm due to overdiagnosis and treatment of clinically insignificant cancers may not be captured by breast cancer-specific mortality. Instead, we examined all-cause mortality as a function of missed annual mammography examinations before breast cancer diagnosis. MATERIALS AND METHODS. Primary breast cancer cases diagnosed in the Marshfield Clinic Health System from 2002 through 2008 were identified for retrospective review, and whether annual mammography examinations had been performed in the 5 years before diagnosis was assessed. RESULTS. Analyses were performed on 1421 women with breast cancer. After adjustment of data for age, comorbidity status, a family history of breast cancer, insurance status, medical encounter frequency, and the calendar year, women who had missed any of the previous five annual mammography examinations had a 2.3-fold increased risk of all-cause mortality compared with subjects with no missed mammography examinations (hazard ratio = 2.28; 95% CI, 1.58-3.30; p < 0.0001). Additionally, an analysis by the number of missed annual mammography examinations showed a progressive increase in hazard as the number of missed mammography studies increased. CONCLUSION. These results suggest that annual mammography before breast cancer diagnosis is predictive of increased overall survival. A stepwise decline in overall survival was noted for each additional missed mammography examination. These results are similar to findings in the literature for breast cancer-specific mortality and illustrate the importance of recommending annual mammography to all eligible women.