Background: Although clinical breast examinations (CBEs) provide important opportunities to detect breast cancer, little is known about factors that affect cancer detection during CBEs performed in community settings. To evaluate several potential factors, we analyzed data from 1,056,153 cancer screening records reported to the National Breast and Cervical Cancer Early Detection Program (NBCCEDP).
Methods: Using case-series methods, we compared 2159 cancers missed during CBEs with 3161 cancers detected during CBEs. Cancers missed during CBE were found by mammography and confirmed by biopsy or fine needle aspiration.
Results: After controling for cancer stage, tumor size, and breast symptoms at time of CBE, we found that patient age and CBE history were significantly associated with the likelihood of cancer detection. Compared to women 50-59, women 40-49 were more likely to have their cancer detected during CBE (odds ratio (OR) = 1.84, 95% confidence interval (95% CI) 1.47-2.29), while women 70 and older were less likely to have it detected (OR = 0.74, 95% CI: 0.55-1.00). Among women receiving their first NBCCEDP-funded CBE, 67.5% had their cancer detected by CBE. Among women receiving their second or third CBE, the values were 59.3 and 48.8%, respectively. In an adjusted logistic model, a significant inverse relationship was observed between number of prior CBEs and percent of cancers detected in the index CBE (OR = 0.79, 95% CI: 0.72-0.88).
Conclusions: Among women diagnosed with breast cancer, older women and those who have had multiple CBEs were more likely to have their cancer missed during CBE.