Background: There is little information on the quality of breast self-examination (BSE) and associated outcomes.

Method: We conducted a retrospective cohort study of 27,421 women enrolled in a Pacific Northwest health plan. We linked responses regarding BSE quality from a questionnaire to subsequent screening and diagnostic efforts.

Results: A total of 75% of the women performed BSE. We rated BSE quality as adequate in 27%. Women who reported higher BSE duration, frequency, and quality were more likely to have diagnostic mammograms. Participants ultimately diagnosed with breast cancer (N = 300) were significantly less likely to report performing BSE. Tumor size and stage were not associated with BSE behavior.

Conclusion: A high proportion of women perform BSE, but few do so adequately. We found no evidence for benefit of BSE. It is time to ask whether systematic BSE performance should continue to be encouraged.