At Congressional hearings in late October, critics, especially
from the women's movement, told of an increased risk of blood
clotting, and liver and endometrial cancer, associated with the
use of the anti-estrogen drug tamoxifen. Nevertheless, senior
NCI officials said (10/26) that they intended to move forward with
a 10-year breast cancer prevention trial begun last spring.
The Breast Cancer Prevention Trial (BCPT) has begun testing
the powerful drug on 16,000 healthy women who are thought to be
at high risk of developing breast cancer. It is the largest such
trial ever conducted and the centerpiece of NIH's new emphasis
on women's health issues.
"No intervention is totally without risk, and tamoxifen does have
some potential side effects," admitted Peter Greenwald, NCI
director of cancer prevention. But he told the House
subcommittee on human resources and intergovernmental
relations that "the likely benefits...are a reduction in breast
cancer, in heart disease, and maintenance of bone density. It is
important to keep in mind the dimensions of these potential
benefits."
Among women who have had one breast removed for cancer,
tamoxifen is believed to reduce the risk of cancer developing in
the other breast. The idea is to extend these findings to women
who have not yet developed any disease. Since tamoxifen is
carcinogenic, however, women are being asked to take a
worrisome risk. And according to some reports, potential
participants are shying away from this trial, which like many
NCI trials is hampered by lack of popular participation.
Tamoxifen is made by ICI Pharmaceuticals, a British drug giant.
If tamoxifen is generally recommended for all women allegedly at
high risk of breast cancer it would open a huge new market and
represent a tremendous windfall for this and other
pharmaceutical companies.
