RISK-FACTORS FOR BENIGN BREAST DISEASE ACCORDING TO HISTOPATHOLOGICALTYPE - COMPARISONS WITH RISK-FACTORS FOR BREAST-CANCER

We evaluated risk factors for benign breast disease by using a case-co ntrol study method, The series was taken from participants in breast c ancer screening programs during 1978-1986 in Miyagi Prefecture, Japan. All benign breast lesions diagnosed during this period were reviewed and reclassified into proliferative and non-proliferative types based on the Dupont and Page classification, Data on 382 benign breast disea se cases (130 proliferative-type cases and 252 nonproliferative-type c ases) and 1,489 screening year-, age- and screening area-matched norma l controls were used for analysis, Nulliparity or low parity and famil y history of breast cancer in mother or sisters were significantly ass ociated with an increased risk of proliferative type, Premenopausal st atus was significantly associated with an increased risk of non-prolif erative type, No significant association with history of lactation for the last child was observed in either type, but the risk of prolifera tive type increased with increasing duration of lactation (P=0.08). A comparison between the present findings and the risk factors for breas t cancer indicated epidemiologic similarities between proliferative be nign and malignant breast lesions in general, The associations of thes e two lesions with lactation patterns were, however, dissimilar.