Tamoxifen’s Protection Extends to Women With BRCA
Mutations ------------------------------------------------------------------ TORONTO-Tamoxifen
appears to protect breast-cancer patients with BRCA mutations from
contralateral disease.
In the first study to assess the
effect of tamoxifen (Nolvadex, AstraZeneca) on known carriers of BRCA1 and
BRCA2 mutations, an international team found that breast-cancer patients
with the mutations given tamoxifen were 50% less likely to develop disease
in the other breast than those who did not take the drug.
The case-control study found that 64 women with BRCA1
mutations taking tamoxifen had a 62% risk reduction for developing
contralateral disease, Dr. Steven A. Narod of the University of
Toronto’s Sunnybrook and Women’s College Health Science Centre and
colleagues reported in the Dec. 2 Lancet. The 39 women with BRCA2
mutations taking the drug had a risk reduction of 32%.
However, this protective effect did not last longer than 10 years after
the drug was stopped. This point, Dr. Narod said, should be noted by young
women considering a prophylactic mastectomy.
The study
compared 209 women with bilateral breast cancer and BRCA1 or BRCA2 mutations
and 384 women with unilateral disease and BRCA1 or BRCA2 mutations. The
women, accrued from genetics counseling programs at 34 centers in eight
countries, were interviewed an average of 10 years after diagnosis. Thirteen
percent of women with BRCA1 mutations reported tamoxifen use, as did 33% of
women with BRCA2 mutations.
The greatest reduction in risk was
among women who’d had an oophorectomy in addition to taking tamoxifen. They
were 80% less likely to develop contralateral disease than women who had
never taken tamoxifen and had not had an oophorectomy. The effects of these
two treatments were independent but additive, the group reported, and
they persisted beyond 10 years. Chemotherapy was also an independent source
of risk reduction.
The protective effect of tamoxifen increased
with use up to four years, fading after that.
Dr. Narod said
that the effect of tamoxifen on reduction of cancer- associated mortality
hadn’t been established, and it wasn’t clear whether tamoxifen slows the
growth of existing tumors or reduces the development of new
ones.
Nevertheless, he said, the group believes that
tamoxifen will "reduce the occurrence of primary cancers in BRCA1 and BRCA2
mutation carriers, and that tamoxifen chemoprevention and other options
should be discussed with healthy women" who carry the
mutations.
