Prevalence of incidental breast cancer and precursor lesions in autopsy studies: a systematic review and meta-analysis.

Background: Autopsy studies demonstrate the prevalence pool of incidental breast cancer in the population, but estimates are uncertain due to small numbers in any primary study. We aimed to conduct a systematic review of autopsy studies to estimate the prevalence of incidental breast cancer and precursors.

Methods: Relevant articles were identified through searching PubMed and Embase from inception up to April 2016, and backward and forward citations. We included autopsy studies of women with no history of breast pathology, which included systematic histological examination of at least one breast, and which allowed calculation of the prevalence of incidental breast cancer or precursor lesions. Data were pooled using logistic regression models with random intercepts (non-linear mixed models).

Results: We included 13 studies from 1948 to 2010, contributing 2363 autopsies with 99 cases of incidental cancer or precursor lesions. More thorough histological examination (≥20 histological sections) was a strong predictor of incidental in-situ cancer and atypical hyperplasia (OR = 126·8 and 21·3 respectively, p < 0·001), but not invasive cancer (OR = 1·1, p = 0·75). The estimated mean prevalence of incidental cancer or precursor lesion was 19·5% (0·85% invasive cancer + 8·9% in-situ cancer + 9·8% atypical hyperplasia).

Conclusion: Our systematic review in ten countries over six decades found that incidental detection of cancer in situ and breast cancer precursors is common in women not known to have breast disease during life. The large prevalence pool of undetected cancer in-situ and atypical hyperplasia in these autopsy studies suggests screening programs should be cautious about introducing more sensitive tests that may increase detection of these lesions.