Drugs reduce risk of breast cancer in midst of side effects
<br>By Jameel Naqvi
Daily Staff ReporterNovember 21st, 2003
An ongoing study raises the exciting possibility that doctors
will be able to reduce the risk of breast cancer without
contributing to other health problems.
Tests in the U.S. and Canada are assessing the effectiveness of
the drugs Tamoxifen and Raloxifene in preventing breast cancer. The
University’s Comprehensive Cancer Center and St. Joseph Mercy
Hospital in Ann Arbor are both participants in the study.
A 1998 trial showed Tamoxifen, which has been on the market for
more than 20 years, reduced the incidence of breast cancer by 50
percent over a placebo. But the drug also increases the risk of
blood clots and endometrial, or uterine, cancer, said Sofia
Merajver, the center’s principal investigator on the
study.
“There is some early evidence that Raloxifene is less apt
to cause uterine cancer than Tamoxifen,” said Virginia
LeClaire, a nursing practitioner at the center.
Raloxifene has not been approved to treat breast cancer. It is
now used to treat osteoporosis in postmenopausal women, as it has
not yet been determined whether the drug is safe among younger
women, Merajver said.
Because of this, only postmenopausal women are subjects in the
recent study of Tamoxifen and Raloxifene.
Both drugs bind to estrogen receptors to prevent the hormone
from spurring the growth of cancerous cells, but there are subtle
differences between them, Merajver said.
The results of the STAR trial could lead to a role reversal or
even cause one of the drugs to fall out of favor.
“Both of these drug companies are taking a gamble”
by participating in the study, said LeClaire.
Despite the high stakes involved, the trial is insulated from
drug company influence, Merajver said. Though the study is funded
by the two drug makers along with the National Cancer Institute,
the funds are administered by a third party, she said.
The cancer institute also funded a study, released last month,
which found the drug Letrozole improved upon the disease-free
survival rate of breast cancer patients by 6 percent compared with
a placebo.
“(Cancer) relapse is a death sentence,” St. Joseph
Mercy oncologist Elaine Chottiner said.
“If you convert six out of 100 women from untreatable to
treatable, then multiply that by the thousands of women diagnosed
with breast cancer each year, that’s significant.”
The significant survival advantage conferred by Letrozole led
researchers to halt the study early and give the women in the
control group the option of taking Letrozole free of charge of for
the next five years.
One of these women was Dentistry School Prof. Karen Ridley.
“There was a feeling of comfort in knowing that you might
be taking something to stop the breast cancer from coming
back,” Ridley said.
Ridley received the placebo for three years and has been taking
Letrozone for the past week.
She was diagnosed with breast cancer in 1994, for which she
underwent chemotherapy and mastectomies in both breasts. She also
was treated with Tamoxifen, which in addition to its preventative
role is used to stop the recurrence of breast cancer.
The study was administered locally at St. Joseph Mercy, where 17
women volunteered to be test subjects. Though the drug shows
promise in treating early stage breast cancer, Chottiner expressed
concerns about Letrozole and the study.
“Letrozole increases the risk of osteoporosis,” she
said. “(The study) cannot gauge the long-term effect on bone
density.”
She added that the time frame may have been too short because
breast cancer is undetectable in its incipient stages.
“You’re caught between a moral obligation to inform
patients of the results of the study and a research obligation to
gather more data,” Chottiner said.
“One wonders what role drug companies have in (the choice
to end the study early),” she added. Novartis, maker of
Letrozole, stands to make a fortune from the study, she said.
One requirement was that the women in the study must have had
five years of Tamoxifen treatment. Tamoxifen is not prescribed to
patients for more than five years because cancer cells have the
ability to adapt and become less responsive to the drug.
Letrozole, which is already used to treat advanced breast cancer
in postmenopausal women, may take the place of Tamoxifen in
preventing recurrence of the disease after those five years are
up.
But Letrozole is expensive, at $180 to $200 each month. Patients
can obtain the generic version of Tamoxifen for about $30 per
month, Chottiner said.
“There will be women who don’t get the drug because
it is too expensive,” Chottiner said.
“Women without prescription coverage may have trouble
affording the drug.”
No data has yet been released for the STAR trial, which will not
end for more than a year, but in a smaller study Raloxifene reduced
the incidence of breast cancer by 50 percent.
Printed from www.michigandaily.com on Sat, 26 May 2012 19:00:53 -0400