Screening clinical breast examination: how often does it miss lethal breast cancer?

Abstract

BACKGROUND: Although most American women regularly receive screening clinical breast examination (CBE), little is known about CBE accuracy in community practice. We sought to estimate the rate of cancer detection (sensitivity) of screening CBE performed by community-based clinicians on women who ultimately died of breast cancer, as well as to identify factors associated with accurate detection. SUBJECTS AND METHODS: We evaluated CBE accuracy among asymptomatic female health plan enrollees in five states (WA, OR, CA, MA, and MN) who received a CBE within 1 year of breast cancer diagnosis and who died of breast cancer within 15 years of diagnosis (N = 485). Sensitivity was estimated as the proportion whose exam was abnormal. Bivariate and logistic regression analyses identified patient characteristics associated with cancer detection. RESULTS: An abnormality was noted on screening CBE in one of five women who ultimately succumbed to breast cancer (sensitivity = 21.6%; 95% confidence interval [CI] = 18.1% to 25.6%). The odds of a true-positive screening CBE (sensitivity) were decreased among women using estrogen (odds ratio [OR] = 0.23; 95% CI = 0.07 to 0.80), receiving a Pap smear during the same visit as CBE (OR = 0.45; 95% CI = 0.27 to 0.72), and with increasing chronic disease comorbidity (P(trend) = .08). CONCLUSION: Screening CBE as performed in the community may be insufficiently sensitive to detect most lethal breast cancers. Low sensitivity of screening CBE in community practice may be partly attributable to its performance alongside time-consuming clinical tasks such as Pap smear screening or chronic illness care.