Aspirin
saves lives of Cancer patients suffering heart
attacks, despite fears of bleeding
Newswise — Many cancer patients who have heart
attacks often are not treated with life saving
aspirin given the belief in the medical community
that they could experience lethal bleeding.
Researchers at The University of Texas M. D.
Anderson Cancer Center, however, say that notion is
now proven wrong and that without aspirin, the
majority of these patients will die.
Researchers say that their study, to be published in
the February 1, 2007 issue of the journal Cancer
and now available online, turns common medical
assumptions upside down and will likely change
medical practice for cancer patients. Because
aspirin can thin blood and cancer patients
experience low platelet counts and abnormal
clotting, physicians view aspirin as a relative
contraindication. Given that blood platelets are
responsible for the clotting process, physicians do
not eagerly prescribe aspirin as a standard
treatment.
In this study, however, the investigators found that
9 of 10 cancer patients with thrombocytopenia (low
platelet count) who were experiencing a heart attack
and who did not receive aspirin died, whereas only
one patient died in a group of 17 similar cancer
patients who received aspirin. They also found
aspirin helps cancer patients with normal platelet
count survive heart attacks, just as it does for
people without cancer.
"The notion that heart attacks in patients with low
platelets should be treated with clot-dissolving
aspirin defies logic, that is unless you suspect
that the cancer is interfering with platelet
function," says the study's senior investigator and
author, Jean-Bernard Durand, M.D., assistant
professor in the Department of Cardiology at M. D.
Anderson Cancer Center.
"We believe tumors may be releasing chemicals that
allow the cancer to form new blood supplies which
makes blood more susceptible to forming clots."
Durand, a heart failure specialist, says. "There
appears to be a platelet paradox suggesting that
cancer may affect the mechanism of the way that
blood clots, and from this analysis, we have found
that the single most important predictor of survival
in these patients is whether or not they received
aspirin." Durand says more research is needed to
better understand this contraindication.
According to the World Health Organization there are
approximately 10 million cancer patients worldwide,
of which 1.5 million may develop blood clots during
their cancer treatment and, as such, are at a much
higher risk of dying from heart disease if not
treated properly. "Now that we have this study, it
would be a travesty if you survive treatment for
cancer only to die of a heart attack soon
thereafter," Durand says.
According to Durand, no guidelines currently exist
for treatment of heart attacks in patients with
cancer. He says that physicians are especially
perplexed about what to do for cancer patients with
thrombosis (blood clots), a condition that affects
about 15 percent of all cancer patients and can be
due to the use of chemotherapy or the presence of
cancer.
Durand came to M. D. Anderson in 2000 to start the
Cardiomyopathy Services, which is believed to be the
only program in the world specifically designed to
look at cardiovascular complications caused by
chemotherapy treatment. He is also the co-founder of
CONQUER (Cardiology Oncology International Quest to
Educate and Research Heart Failure in Cancer), a
newly created organization with goals of increasing
the success of chemotherapy by reducing
cardiovascular disease as a barrier and long term
risk.
He and anesthesiologist Mona Sarkiss, M.D., Ph.D.,
made the observation that patients with
thrombocytopenia who suffered a heart attack and
were being treated in the intensive care unit at M.
D. Anderson tended to die more often when they were
not given aspirin. However, they noted that some of
the patients given aspirin and/or beta-blockers had
"great" clinical outcomes. "Because no practice
guidelines exist, physicians were treating their
patients with great variability and the disparity
was obvious," Durand says.
Sarkiss, who is the study's lead author, Durand, and
a team of researchers which included investigators
from Baylor College of Medicine and Duke University
Medical Center, conducted a retrospective analysis
of cancer patients treated for heart attacks at M.
D. Anderson Cancer Center in 2001. These 70 patients
were divided into two groups based on their platelet
counts, and data was collected on the use of
aspirin, bleeding complications, and survival.
They found that heart attack patients with low
platelets who did not receive aspirin had a
seven-day survival rate of 6 percent, compared with
90 percent survival in those who received aspirin.
Dr. Durand notes that there were no severe bleeding
complications in patients who used aspirin.
Conversely, patients with low platelet counts who
formed a blood clot and were not exposed to aspirin
died.
The beneficial effect of aspirin also was seen in
patients with normal platelet counts. Seven-day
survival was 88 percent in aspirin-treated patients
as compared to 45 percent in patients who did not
receive aspirin, the researchers found.
Durand observed that these deaths rates are
abnormally high. "In the non-cancer patient with
acute coronary syndrome anywhere in the United
States, an expected seven-day mortality is less than
1 percent," he says.
There were parallel findings for those patients in
either group who were treated with beta-blockers,
which block the heart's use of adrenalin. The
protective effect was not as strong as seen with
aspirin, but was still life saving.
In those patients with a normal platelet count, 91
percent survived seven days when treated with
beta-blockers, whereas 36 percent survived if they
were not treated with the agent. In the
thrombocytopenic group, 73 percent survived seven
days when treated with beta-blockers, whereas only
13 percent survived if they were not treated.
Investigators working with Durand and Sarkiss were:
Andrew Shaw, M.D., from Duke; Nasser Lakkis, M.D.
from Baylor; and S. Wamique Yusuf, M.D., Carla
Warneke, M.D., Gregory Botz, M.D., Cheryl
Hirsch-Ginsburg, M.D., J. Chris Champion, M.D.,
Joseph Swafford, M.D., and Daniel Lenihan, M.D.,
from M. D. Anderson.
