Systematic review of fibroadenoma as a risk factor for breast cancer.

Fibroadenoma (FA) is a common breast lesion occurring in 25% of asymptomatic women. Several studies considered FA as a risk factor for breast cancer, prompting a systematic review of the literature. We selected cohort and case-control studies. Seven studies satisfied the selection criteria. Dupont et al. (1994) and McDivitt et al. (1992) were considered to provide the strongest evidence, showing the relative risk for excised FA without hyperplasia in the range 1.48-1.7, with hyperplasia 3.47-3.7, and with hyperplasia and atypia 6.9-7.29, persisting for more than 20 years. Five studies by Levi et al. (1994), Ciatto et al. (1997), Moskowitz et al. (1980), Carter et al. (1988), and Levshin et al. (1998), were considered to provide weaker evidence, although they showed similar results. None of the results could be used to quantify the risks of excised, non-excised, and asymptomatic FA. More care should be taken in managing patients with complex FAs and FAs with hyperplasia with or without atypia. Core biopsy may be a better option in diagnosis of FAs. Regular screening may be advisable in patients with FAs and a family history of breast cancer in a first-degree relative. More rigorous research is needed in this area.