THURSDAY, May 31 (HealthDay News) -- People with type 2 diabetes
taking Actos (pioglitazone) to control blood sugar may put
themselves at risk for bladder cancer, according to a new Canadian
Although the absolute risk of anyone developing bladder cancer
remains very low, taking the Actos pill for two years can double
the risk, the researchers said.
"We believe physicians, patients and regulatory agencies should
be aware of this association when assessing the overall risks and
benefits of this therapy," said lead researcher Laurent Azoulay,
from the Center for Clinical Epidemiology at the Lady Davis
Institute at Jewish General Hospital in Montreal.
"The association between the use of pioglitazone and bladder
cancer is controversial, with several studies reporting conflicting
results, from modest increased risks to no association," said
Azoulay, who also is an assistant professor in the oncology
department at McGill University in Montreal.
The report was published online May 31 in the journal
This is not the first time the drug has been linked to bladder
cancer. In 2011, the U.S. Food and Drug Administration required the
drug maker, Takeda Pharmaceuticals North America, to add a warning
of the risk of bladder cancer to the drug's label.
Actos's sister drug, Avandia (rosiglitazone), has been linked to
increased heart risks. Both drugs are in a class of drugs called
thiazolidinediones that help control blood sugar levels in patients
with type 2 diabetes. Avandia was not associated with an increased
risk of bladder cancer in this study.
For this study, Azoulay's team collected data on nearly 116,000
people treated for diabetes from 1988 to 2009 and listed in the
General Practice Research Database, which contains records from
more than 600 medical offices in the United Kingdom.
During almost five years of follow-up, 470 patients were
diagnosed with bladder cancer. Among patients who had taken Actos,
the researchers found an 83 percent increase in the relative risk
for bladder cancer.
But they said the absolute risk was low -- 89 cases among
100,000 people who had taken the drug at any time during the five
years of follow-up. In the general U.K. population, the rate of
bladder cancer among those 65 and older is 73 cases per
The researchers also found that the risk increased as cumulative
dosage increased. For those who had taken Actos for two years or
longer -- consuming 28,000 milligrams or more in total -- the
relative risk of bladder cancer was increased 88 percent to 137
cases per 100,000 patients.
Weighing the risks and benefits, doctors who treat patients
disagree about the continued use of Actos.
Dr. Spyros Mezitis, an endocrinologist at Lenox Hill Hospital in
New York City, said "we need to be more careful with the use of
The whole class of these drugs has come under fire, he said. "If
there are more studies like this, we will not be using this
medication," he added.
Mezitis said he starts new type 2 diabetes patients on other
drugs such as metformin to control blood sugar, rather than Actos.
Because it's a generic drug, metformin also is less expensive than
Mezitis also thinks more patients with type 2 diabetes will get
insulin earlier instead of using drugs like Actos.
"We have to tailor treatment to each patient, and there are
other ways of controlling blood sugar," he said.
Another expert, Dr. Joel Zonszein, a professor of clinical
medicine at Albert Einstein College of Medicine and an
endocrinologist at the Clinical Diabetes Center at Montefiore
Medical Center in New York City, said he thinks the study is weak,
and the risk of bladder cancer is small.
"There is an important role for these medications," he said. "I
am probably one of the last doctors who is still supporting the use
of these medications."
Zonszein said he starts patients on Actos in combination with
other drugs such as metformin to aggressively lower blood sugar.
Patients, however, need to know the risks, he said.
For more information on diabetes, visit the
U.S. National Library of Medicine.