Performance of screening mammography among women with and without a first-degree relative with breast cancer

Background: Although it is recommended that women with a family history of breast cancer begin screening mammography at a younger age than average-ris k women, few studies have evaluated the performance of mammography in this group. Objective: To compare the performance of screening mammography in women wit h a first-degree family history of breast cancer and women of similar age w ithout such history. Design: Cross-sectional. Setting: Mammography registries in California (n = 1) New Hampshire (n = 1) , New Mexico (n = 1), Vermont (n = 1) Washington State (n = 2), and Colorad o (n = 1). Measurements: Risk factors for breast cancer; results of first screening ex amination captured for a woman by a registry; and any invasive cancer or du ctal carcinoma in situ identified by linkage to a pathology database, the S urveillance, Epidemiology, and End Results program, or a state tumor regist ry. Results: The number of cancer cases per 1000 examinations increased with ag e and was higher in women with a family history of breast cancer than in th ose without (3.2 vs. 1.6 for ages 30 to 39 years, 4.7 vs. 2.7 for ages 40 t o 49 years, 6.6 vs. 4.6 for ages 50 to 59 years, and 9.3 vs. 6.9 for ages 6 0 to 69 years). The sensitivity of mammography increased significantly with age (P = 0.001 [chi-square test for trend]) in women with a family history and in those without (63.2% [95% CI, 41.5% to 84.8%] vs. 69.5% [Ct, 57.7% to 81.2%] for ages 30 to 39 years, 70.2% [CI, 61.0% to 79.5%] vs. 77.5% [CI , 73.3% to 81.8%] for ages 40 to 49 years, 81.3% [CI, 73.3% to 89.3%] vs. 8 0.2% [CI, 76.5% to 83.9%] for ages 50 to 59 years, and 83.8% [CI, 76.8% to 90.9%] vs. 87.7% [Cf, 84.8% to 90.7%] for ages 60 to 69 years). Sensitivity was similar for each decade of age regardless of family history. The posit ive predictive value of mammography was higher in women with a family histo ry than in those without (3.7% vs. 2.9%; P = 0.001). Conclusions: Cancer detection rates in women who had a first-degree relativ e with a history of breast cancer were similar to those in women a decade o lder without such a history. The sensitivity of screening mammography was i nfluenced primarily by age.