|
From our own Dr. Slamon.......comments
I found this very interesting, just wondering how the rest of you felt.
By Robert Bazell Chief science and health correspondent Updated: 5:52
p.m. ET June 5, 2007 What if an estimated 100,000 breast cancer patients
got drugs that did nothing to combat their cancer, but put them at risk
for heart failure and leukemia?
That is the implication of new research that was presented in private
session at this week’s meeting of the American Society of Clinical
Oncology(ASCO) in Chicago.
The research, from Dr. Dennis Slamon, chief of oncology at the
University of California, Los Angeles, suggests that the most widely
used chemotherapy drugs may not benefit most women. Although the
research hasn't been published or peer-reviewed yet, it is expected
to be soon.
The drugs are a common class of treatments called anthracyclines,
including doxorubicin, epirubicin, and mitoxantrone. Since their
introduction in the 1980s anthracyclines have replaced older
chemotherapy drugs in the combination therapies given to women.
Administered in the months after surgery and radiation, the chemotherapy
is intended to reduce the chances of a life-threatening recurrence of
cancer, especially in women at high risk for relapse.
Early on, researchers understood that anthracyclines could cause heart
failure in some patients. Recently, evidence has accumulated about the
additional risk of leukemia, which can strike years or decades after the
treatment.
Evidence for the effectiveness of anthracyclines versus the older drugs
remained murky. Then, a 1998 meta-analysis (a study of all the previous
studies) found the anthracyclines did a 4 percent better job at
preventing recurrence. Despite their side effects, that study elevated
the drugs to the standard of care.
Treating many to help few The UCLA research questions that treatment.
Slamon played a key role in the discovery and development of the hugely
successful breast cancer drug Herceptin. Herceptin, which changed the
way the disease is treated, specifically targets a gene called Her-2
that is overexpressed in 20 percent to 25 percent of breast cancers (a
gene is overexpressed when its effect becomes excessive in the body).
Herceptin’s success proved that breast cancer is not one disease, but
many, with each benefiting from a tailored treatment.
In this latest study, Slamon looked at a more recently discovered gene
called Topoll-2, which is sometimes, but not always, overexpressed
along with Her-2. Anthracyclines stop breast cancer because they
target Topoll-2.
Slamon examined tissue samples from more than 2,000 women who took part
in seven clinical trials. His analysis showed that anthracyclines work
only in women who overexpress the Topoll-2 gene. Such women account for
8 percent of breast cancer cases.
The anthracyclines — with all their side effects — have almost no effect
in 92 percent of breast cancer cases.
“It seems apparent that we are treating patients who don't need the drug
to get at that group who have a huge benefit,” Slamon told me. “And now
we need to direct our therapy and target it more specifically.”
'Exciting result' Even when other cancer doctors were willing to use
anthracyclines only as targeted therapy, they couldn’t. There is no
commercial test yet for the Topoll-2 gene, although there likely will be
in a few months.
Nevertheless, Johns Hopkins breast cancer specialist Dr. Nancy Davidson
calls the findings “an exciting result.”
“It's early; it's provocative. We are waiting to see it go through peer
review in the usual fashion,” says Davidson, who is incoming president
of ASCO. “But there's a lot of buzz.”
Fran Visco, a cancer survivor and president of the National Breast
Cancer Coalition, agrees the work needs to be published and peer-
reviewed — very soon.
“This is going to be a sea change in how we treat breast cancer,” she
told me. “There is no reason we shouldn't be moving very quickly to
publish it and quickly to figure out how we're going to implement it in
practice. Women deserve no less.”
|
Threaded Mode