By Nancy Deutsch
NEW YORK, Jun 01 (Reuters Health) - New research suggests the use of
combination hormone replacement therapy (HRT) increases the risk of developing a
certain type of breast cancer known as lobular breast carcinoma.
Women taking combination HRT for at least 6 months were more than twice as
likely to develop lobular tumors as nonusers of menopausal hormones,
investigators from the Fred Hutchinson Cancer Research Center in Seattle,
Washington have found. These women are not more likely to develop ductal cancer,
the more common type of breast cancer among the general population, noted Dr.
Christopher I. Li. The findings are published in the June 1st issue of the
journal Cancer.
Although lobular cancer grows as a sheet of cells, making it harder to
detect on mammography or physical exam, "women with lobular cancers have
slightly higher survival rates," Li told Reuters Health. The researchers decided
to conduct this study because clinically, physicians were reporting that women
taking HRT containing both estrogen and progesterone seemed to have more of the
rarer form of cancer, Li explained.
At the same time this study was published, the research team published
another study showing that between 1977 and 1995, the incidence of lobular
cancer grew among American women, but the incidence of ductal cancer reached a
plateau, Li said. Combination HRT began to be popular in the late 1970s, leading
investigators to think there might be a connection, he added.
The researchers interviewed 537 white women aged 50 to 64 who were diagnosed
with confirmed breast cancer as part of the Cancer Surveillance System between
January 1988 and June 1990 in King County, Washington. In addition, the team
interviewed 492 ('control') women of the same age and geographical area who did
not have breast cancer.
Of the women with cancer, 58 had lobular tumors and 370 had ductal tumors.
The other women had breast cancer of other types. Those women who had taken
combination HRT for at least 6 months were 2.6 times more likely to develop
lobular breast tumors than the women in the control group. Women who had ever
used combination HRT were 2.1 times as likely to have lobular cancer.
Women who had taken unopposed estrogen were also more likely to develop
lobular breast tumors, but to a lesser degree. None of the women on HRT were
more likely to develop ductal tumors, the findings indicate.
There were relatively few cases of lobular cancers (58) and this is "only a
single study, so (although) we think there is something going on, it's too soon
to make clinical recommendations," Li told Reuters Health. His team plans to
conduct more studies in this area, he said.
