After Breast Cancer: How Long on Tamoxifen?
5 Years Is Better than 2 for Younger Patients, Italian Study Shows
Oct. 24, 2005 -- Taking the drug tamoxifen for five years instead of two
years improves survival in younger women with breast cancer, according to a new
But the survival advantage didn't show up right away and was only seen in
women younger than 55 with estrogen receptor-positive cancer. Estrogen
receptor-positive cancer grows when exposed to estrogen and is more responsive
to antiestrogen therapy.
Tamoxifen, which works as an antiestrogen, has long been a staple of breast
cancer treatment. The researchers aren't calling for any treatment changes
since their study was relatively small.
The report by Maurizio Belfiglio, MD, and colleagues appears in
Belfiglio works in the clinical pharmacology and epidemiology department of
the Italian research institute Consorzio Mario Negri Sud.
Some (but not all) breast cancers are fueled by the hormone estrogen.
Tamoxifen blocks estrogen from latching onto estrogen receptor-positive breast
The most common side effects of tamoxifen are hot flashes and vaginal
discharge. But there is a higher risk for blood clots, stroke, and uterine
cancer, which can be fatal. Women who are pregnant or are planning to become
pregnant should not take the medication. Also, people with a history of blood
clots or who are already taking blood-thinning medication should not take
Tamoxifen has been used in breast cancer therapy for more than 20 years.
It's usually given for five years after initial breast cancer treatments (such
as surgery, chemotherapy, and radiation).
Could a shorter dose of tamoxifen work as well for survival? That question
was explored by Belfiglio's team.
Tamoxifen: 2 Years vs. 5 Years
All of the women in their study took tamoxifen for at least two years. About
half stopped after two years; the rest took tamoxifen for a total of five
The women were 50-70 years old when the study started. Women with
early-stage invasive breast cancer were included.
About 60% had estrogen receptor-positive breast cancer. About 25% hadn't had
their cancer's estrogen status checked.
Virtually all of the women got surgery for breast cancer. About 40% got
radiation and 10% got chemotherapy.
A total of 549 women died during the nine-year study. Survival was 44% more
likely for younger women (up to age 55) with estrogen receptor-positive breast
cancers, the study shows.
The survival benefit of taking tamoxifen for five years instead of two years
wasn't immediate. That advantage appeared nine years after the women had first
been diagnosed with breast cancer.
Older women had different results.
"No clear benefit was documented in women older than 55 years of
age" who took tamoxifen for five years instead of two years, the
More Work Ahead
The small number of patients might have mattered, so more studies are
needed, the researchers note.
"We believe that our findings should only be used to generate further
investigation, rather than to draw definitive conclusions, and to underline the
importance of a long follow-up in trials exploring the effects of hormonal
therapy in breast [cancer]," they write.
The study was funded by the drug company AstraZeneca Italia.