News Author:
Laurie Barclay, MD
CME Author: Désirée Lie, MD, MSEd
Feb. 21, 2006 - Menopausal hormonal therapy is associated with 3 types of
breast cancer, according to the results of a population- based case-control
study reported in the February issue of Breast Cancer Research.
"Use of menopausal hormone therapy has been shown to increase the risk
of breast cancer, and data indicate that combined medium potency estrogen-progestin
therapy (mainly estradiol or conjugated estrogens combined with progestin)
is associated with a higher risk for breast cancer than medium potency estrogen
alone therapy," write Lena U. Rosenberg, MD, from Karolinska Institute
in Stockholm, Sweden, and colleagues. "Studies from the United States
have rather consistently found medium potency estrogen-progestin therapy
to be more strongly associated with lobular than with ductal breast cancer
risk. It is not clear, however, whether use of menopausal hormone therapy
also increases the risk of ductal breast cancer, or whether medium potency
estrogen alone therapy has differential impacts on lobular and ductal breast
cancer risk."
In this population-based study of women in Sweden aged 50 to 74 years, cases
were diagnosed as having invasive ductal (n = 1888), lobular (n = 308),
or tubular (n = 93) breast cancer in 1993 to 1995. These cases were compared
with 3065 age-frequency matched controls randomly selected from the population.
Risks of both ductal and lobular cancer were increased in women who had
used medium-potency estrogen alone. Although medium-potency estrogen-progestin
was associated with increased risks for all subtypes, the estimates for
lobular and tubular cancer were higher than for ductal cancer. With at least
5 years use of medium-potency estrogen-progestin therapy, odds ratios (ORs)
were 5.6 (95% confidence interval [CI], 3.2 - 9.7) for lobular cancer, 6.5
(95% CI, 2.8 - 14.9) for tubular cancer, and 2.3 (95% CI, 1.6 - 3.3) for
ductal cancer.
Low-potency oral estrogen (mainly estriol) appeared to be associated with
an increased risk for lobular cancer, particularly with short- term use.
Reproductive and anthropometric factors, smoking, and past use of oral contraceptives
had similar associations with the 3 breast cancer subtypes, but recent alcohol
consumption of more than 10 g/day was associated with increased risk only
for tubular cancer (OR, 3.1; 95% CI, 1.4 - 6.8).
Study limitations include small number of cases for lobular and tubular
cancer; exposure information self-reported and collected retrospectively;
retrospective design causing potential recall bias; and histologic classifications
by several pathologists at different laboratories.
"Menopausal hormone therapy was associated with increased risks for
breast cancer of both ductal and lobular subtype, and medium potency estrogen-progestin
therapy was more strongly associated with lobular compared with ductal cancer,"
the authors write. "We also found medium potency estrogen-progestin
therapy and alcohol to be strongly associated with tubular cancer. With
some exceptions, most other risk factors seemed to be similarly associated
with the three subtypes of breast cancer."
The National Institutes of Health and the Swedish Cancer Foundation supported
this study. The authors have disclosed no relevant financial relationships.
Breast Canc Res. 2006;8:R11 |
