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.
Kotsopoulos
Joanne
J
Centre for Research in Women's Health, Women's College Hospital, University of Toronto, Room 750, 790 Bay Street, 7th Floor, Toronto, ON M5G 1N8, Canada.
Lubinski
Jan
J
Lynch
Henry T
HT
Klijn
Jan
J
Ghadirian
Parviz
P
Neuhausen
Susan L
SL
Kim-Sing
Charmaine
C
Foulkes
William D
WD
Moller
Pal
P
Isaacs
Claudine
C
Domchek
Susan
S
Randall
Susan
S
Offit
Kenneth
K
Tung
Nadine
N
Ainsworth
Peter
P
Gershoni-Baruch
Ruth
R
Eisen
Andrea
A
Daly
Mary
M
Karlan
Beth
B
Saal
Howard M
HM
Couch
Fergus
F
Pasini
Barbara
B
Wagner
Teresa
T
Friedman
Eitan
E
Rennert
Gad
G
Eng
Charis
C
Weitzel
Jeffrey
J
Sun
Ping
P
Narod
Steven A
SA
Garber
J
J
Osborne
M
M
Fishman
D
D
McLennan
J
J
McKinnon
W
W
Merajver
S
S
Olsson
H
H
Provencher
D
D
Pasche
B
B
Evans
G
G
Meschino
W S
WS
Lemire
E
E
Chudley
A
A
Rayson
D
D
Bellati
C
C
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D001943:Breast Neoplasms / Q000453:epidemiology / Q000235:genetics*; D016022:Case-Control Studies; D005260:Female; D019398:Genes, BRCA1; D024522:Genes, BRCA2; D020022:Genetic Predisposition to Disease; D006579:Heterozygote; D006801:Humans; D008875:Middle Aged; D009154:Mutation; D016017:Odds Ratio; D010298:Parity; D011247:Pregnancy; D011252:Pregnancy Complications, Neoplastic; D012042:Registries; D012307:Risk Factors; D013997:Time Factors