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Parity, age at first birth and the risk of carcinoma in situ of the breast
Author(s) -
Lambe Mats,
Hsieh Chungcheng,
Tsaih ShirngWern,
Ekbom Anders,
Trichopoulos Dimitrios,
Adami HansOlov
Publication year - 1998
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/(sici)1097-0215(19980729)77:3<330::aid-ijc3>3.0.co;2-p
Subject(s) - breast cancer , parity (physics) , medicine , carcinoma in situ , epidemiology , obstetrics , gynecology , breast carcinoma , case control study , population , logistic regression , cancer registry , demography , cohort study , cancer , environmental health , physics , particle physics , sociology
Epidemiological studies of in situ breast cancer are sparse, and the role of reproductive history, an established risk modifier for invasive breast cancer, remains incompletely investigated. To examine possible associations with parity and age at first birth, we undertook a case‐control study nested in a nationwide cohort of Swedish women. The reproductive history of 1,368 women aged 65 or younger with a diagnosis of carcinoma in situ of the breast were compared with that of 6,837 age‐matched controls drawn randomly from a population‐based Fertility Registry. Statistical analyses were performed by conditional logistic regression. Compared to nulliparous women, ever‐parous women were at a reduced risk of carcinoma in situ of the breast. The risk decreased with number of live births, with the estimated risk reduction in the highest parity group (5+), being of the same magnitude as that reported for invasive breast cancer. By contrast, a positive association with increasing age at first birth was somewhat less pronounced than that observed previously in the same data set with respect to invasive breast cancer. Our findings indicate that parity affects the risk of invasive breast cancer and carcinoma in situ similarly, whereas the effect of age at first birth appears to be weaker for the risk of carcinoma in situ . Int. J. Cancer 77:330–332, 1998. © 1998 Wiley‐Liss, Inc.