Hormone therapy and the risk of breast cancer in BRCA1 mutation carriers.
BACKGROUND
Hormone therapy (HT) is commonly given to women to alleviate the climacteric symptoms associated with menopause. There is concern that this treatment may increase the risk of breast cancer. The potential association of HT and breast cancer risk is of particular interest to women who carry a mutation in BRCA1 because they face a high lifetime risk of breast cancer and because many of these women take HT after undergoing prophylactic surgical oophorectomy at a young age.


METHODS
We conducted a matched case-control study of 472 postmenopausal women with a BRCA1 mutation to examine whether or not the use of HT is associated with subsequent risk of breast cancer. Breast cancer case patients and control subjects were matched with respect to age, age at menopause, and type of menopause (surgical or natural). Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated with conditional logistic regression. Statistical tests were two-sided.


RESULTS
In this group of BRCA1 mutation carriers, the adjusted OR for breast cancer associated with ever use of HT compared with never use was 0.58 (95% CI = 0.35 to 0.96; P = .03). In analyses by type of HT, an inverse association with breast cancer risk was observed with use of estrogen only (OR = 0.51, 95% CI = 0.27 to 0.98; P = .04); the association with use of estrogen plus progesterone was not statistically significant (OR = 0.66, 95% CI = 0.34 to 1.27; P = .21).


CONCLUSIONS
Among postmenopausal women with a BRCA1 mutation, HT use was not associated with increased risk of breast cancer; indeed, in this population, it was associated with a decreased risk.
Eisen
Andrea
A
Sunnybrook Regional Cancer Center, Toronto, Ontario, Canada.
Lubinski
Jan
J
Gronwald
Jacek
J
Moller
Pal
P
Lynch
Henry T
HT
Klijn
Jan
J
Kim-Sing
Charmaine
C
Neuhausen
Susan L
SL
Gilbert
Lucy
L
Ghadirian
Parviz
P
Manoukian
Siranoush
S
Rennert
Gad
G
Friedman
Eitan
E
Isaacs
Claudine
C
Rosen
Eliot
E
Rosen
Barry
B
Daly
Mary
M
Sun
Ping
P
Narod
Steven A
SA
D000368:Aged; D001943:Breast Neoplasms / Q000139:chemically induced / Q000453:epidemiology* / Q000209:etiology* / Q000235:genetics; D016022:Case-Control Studies; D015986:Confounding Factors, Epidemiologic; D015914:Estrogen Replacement Therapy / Q000009:adverse effects*; D004967:Estrogens / Q000008:administration & dosage / Q000009:adverse effects; D005260:Female; D019398:Genes, BRCA1; D006801:Humans; D008875:Middle Aged; D015999:Multivariate Analysis; D009154:Mutation; D016017:Odds Ratio; D017698:Postmenopause; D011372:Progestins / Q000008:administration & dosage / Q000009:adverse effects; D018570:Risk Assessment; D012307:Risk Factors; D018401:Sample Size; D011795:Surveys and Questionnaires
D004967:Estrogens; D011372:Progestins