Age at first birth and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers.

An early age at first full-term birth is associated with a reduction in the subsequent development of breast cancer among women in the general population. A similar effect has not yet been reported among women who carry an inherited BRCA1 or BRCA2 mutation. We conducted a matched case-control study on 1816 pairs of women with a BRCA1 (n = 1405) or BRCA2 (n = 411) mutation in an attempt to elucidate the relationship between age at first full-term pregnancy and the risk of developing breast cancer. Information about the age at first childbirth and other pregnancy-related variables was derived from a questionnaire administered to women during the course of genetic counselling. There was no difference in the mean age at first full-term birth in the cases and controls (24.9 years vs. 24.8 years; P = 0.81, respectively). Compared to women whose first child was born at or before 18 years of age, a later age at first full-term birth did not influence the risk of developing breast cancer (OR = 1.00 per year; 95% CI 0.98-1.03; P-trend = 0.67). Stratification by mutation status did not affect the results. These findings suggest that an early first full-term birth does not confer protection against breast cancer in BRCA mutation carriers. Nonetheless, BRCA mutation carriers opting for a prophylactic oophorectomy as a breast and/or ovarian cancer risk-reducing strategy should complete childbearing prior to age 40 when this prevention modality is most effective.

Ainsworth P, Bellati C, Chudley A, Couch F, Daly M, Domchek S, Eisen A, Eng C, Evans G, Fishman D, Foulkes WD, Friedman E, Garber J, Gershoni-Baruch R, Ghadirian P, Isaacs C, Karlan B, Kim-Sing C, Klijn J, Kotsopoulos J, Lemire E, Lubinski J, Lynch HT, McKinnon W, McLennan J, Merajver S, Meschino WS, Moller P, Narod SA, Neuhausen SL, Offit K, Olsson H, Osborne M, Pasche B, Pasini B, Provencher D, Randall S, Rayson D, Rennert G, Saal HM, Sun P, Tung N, Wagner T, Weitzel J


Breast Cancer Res. Treat., 2007, 105 (2)

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