Breast cancer risk following bilateral oophorectomy in BRCA1 and BRCA2 mutation carriers: an international case-control study.
OBJECTIVE
The purpose of this study was to estimate the extent of protection offered against breast cancer by prophylactic oophorectomy in carriers of BRCA1 or BRCA2 mutations and to determine to what extent risk reduction varies with age at oophorectomy, age at diagnosis, and time elapsed since surgery.


METHODS
We analyzed 1,439 patients with breast cancer and 1,866 matched controls derived from a registry of BRCA1 and BRCA2 carriers. We estimated odds ratios (ORs) of breast cancer for having had a bilateral oophorectomy, using conditional logistic regression, matched for parity and for oral contraceptive use.


RESULTS
A previous history of oophorectomy was associated with a significant reduction in breast cancer risk of 56% for BRCA1 carriers (OR = 0.44; 95% CI, 0.29 to 0.66) and of 46% for BRCA2 carriers (OR = 0.57; 95% CI, 0.28 to 1.15). The risk reduction was greater if the oophorectomy was performed before age 40 (OR = 0.36; 95% CI, 0.20 to 0.64 for BRCA1 carriers) than after age 40 (OR = 0.53; 95% CI, 0.30 to 0.91). The protective effect was evident for 15 years post-oophorectomy (OR = 0.39; 95% CI, 0.26 to 0.57).


CONCLUSIONS
Oophorectomy is an effective means of reducing the risk of breast cancer in carriers of BRCA1 mutations. The data suggest oophorectomy is protective in BRCA2 carriers as well, but needs to be confirmed in other studies.
Eisen
Andrea
A
Toronto-Sunnybrook Regional Cancer Center, Toronto, ON, Canada.
Lubinski
Jan
J
Klijn
Jan
J
Moller
Pal
P
Lynch
Henry T
HT
Offit
Kenneth
K
Weber
Barbara
B
Rebbeck
Tim
T
Neuhausen
Susan L
SL
Ghadirian
Parviz
P
Foulkes
William D
WD
Gershoni-Baruch
Ruth
R
Friedman
Eitan
E
Rennert
Gadi
G
Wagner
Teresa
T
Isaacs
Claudine
C
Kim-Sing
Charmaine
C
Ainsworth
Peter
P
Sun
Ping
P
Narod
Steven A
SA
D000328:Adult; D017668:Age of Onset; D019313:BRCA1 Protein / Q000235:genetics*; D024682:BRCA2 Protein / Q000235:genetics*; D001943:Breast Neoplasms / Q000235:genetics* / Q000517:prevention & control*; D016022:Case-Control Studies; D003276:Contraceptives, Oral; D005260:Female; D006579:Heterozygote; D006801:Humans; D008875:Middle Aged; D009154:Mutation; D016017:Odds Ratio; D010052:Ovariectomy; D012307:Risk Factors
D019313:BRCA1 Protein; D024682:BRCA2 Protein; D003276:Contraceptives, Oral