Effect of breast augmentation on the accuracy of mammography and cancer characteristics.

CONTEXT Breast augmentation is not associated with an increased risk of breast cancer; however, implants may interfere with the detection of breast cancer thereby delaying cancer diagnosis in women with augmentation. OBJECTIVE To determine whether mammography accuracy and tumor characteristics are different for women with and without augmentation. DESIGN, SETTING, AND PARTICIPANTS A prospective cohort of 137 women with augmentation and 685 women without augmentation diagnosed with breast cancer between January 1, 1995, and October 15, 2002, matched (1:5) by age, race/ethnicity, previous mammography screening, and mammography registry, and 10 533 women with augmentation and 974 915 women without augmentation and without breast cancer among 7 mammography registries in Denver, Colo; Lebanon, NH; Albuquerque, NM; Chapel Hill, NC; San Francisco, Calif; Seattle, Wash; and Burlington, Vt. MAIN OUTCOME MEASURES Comparison between women with and without augmentation of mammography performance measures and cancer characteristics, including invasive carcinoma or ductal carcinoma in situ, tumor stage, nodal status, size, grade, and estrogen-receptor status. RESULTS Among asymptomatic women, the sensitivity of screening mammography based on the final assessment was lower in women with breast augmentation vs women without (45.0% [95% confidence interval [CI], 29.3%-61.5%] vs 66.8% [95% CI, 60.4%-72.8%]; P =.008), and specificity was slightly higher in women with augmentation (97.7% [95% CI, 97.4%-98.0%] vs 96.7% [95% CI, 96.6%-96.7%]; P<.001). Among symptomatic women, both sensitivity and specificity were lower for women with augmentation compared with women without but these differences were not significant. Tumors were of similar stage, size, estrogen-receptor status, and nodal status but tended to be lower grade (P =.052) for women with breast augmentation vs without. CONCLUSIONS Breast augmentation decreases the sensitivity of screening mammography among asymptomatic women but does not increase the false-positive rate. Despite the lower accuracy of mammography in women with augmentation, the prognostic characteristics of tumors are not influenced by augmentation.