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 |
