Cancer Society concerned by reports people self-medicating with untested compound
Wed Mar 21, 8:23 PM
By Helen Branswell
TORONTO (CP) - The Canadian Cancer Society is urging people with cancer not to use a drug called dichloroacetate or DCA which has shown promise in studies in rats but has never been tested in human cancer patients.
The society issued a statement Wednesday on unauthorized use of the chemical, which reportedly has taken off among desperate cancer patients who are advising each other via the Internet on how to purchase and take DCA.
The society's director of cancer control policy said while she sympathizes with people who are looking for ways to prolong their lives, taking an untested drug which can cause significant side-effects or trigger serious drug interactions isn't the answer.
"It must be extraordinarily difficult dealing with that kind of stage of disease and some of the decisions they have to make," said Heather Logan, a former nurse who worked with cancer patients.
"Having said that, we just don't know whether the use of this substance will actually hasten someone's death . . . . We don't know whether the use of this drug will cause severe side-effects that will reduce significantly somebody's quality of life for the time that they have left.
"And they're very real concerns."
Logan said DCA can cause peripheral neuropathy, in which the nerves in the arms and legs are damaged. People taking DCA run the risk of being unable to walk or speak, she said.
Many approved cancer therapies and other drugs can cause side-effects, and patients and their doctors must weigh those risks versus known benefits to decide whether to proceed. But in the case of DCA there is no evidence to date that it will have any cancer-fighting benefits in people.
And research that seems hugely promising in animals often does not pan out when the mammal being tested is a human, experts say.
"We've cured a lot of rats," noted Dr. Joel Lexchin, Toronto emergency room physician and an expert on the workings of the pharmaceutical industry.
Interest in DCA has exploded since researchers from the University of Alberta published a study in January showing they successfully shrank tumours in rats using the drug, which is cheap and off-patent.
That status makes this situation tricky. As DCA is not a manufactured drug, it has not gone through Health Canada's regulatory approval process, during which the department scrutinizes safety and efficacy data on the drug.
But pharmacists can purchase the bulk active ingredient of DCA, sold as a water-soluable powder, and compound it into a dose form. People who get a prescription for DCA from a physician can then purchase the drug, which has been used to treat certain rare metabolic disorders.
Under Canadian law, the drug can't be advertised or sold, either via the Internet or through a retail pharmacy, without a doctor's prescription.
Health Canada is also urging people not to take an untested compound.
"Appropriate clinical trials haven't been conducted to demonstrate that dichloroacetate has the appropriate safety profile and that it will be effective against cancer," said spokesperson Jirina Vlk.
"So therefore Health Canada couldn't recommend the use of DCA in humans for the treatment of cancer outside of a clinical trial environment."
The researchers, led by Dr. Evangelos Michelakis, are trying to expedite human trials.
The cancer society said its research arm, the National Cancer Institute of Canada, is investigating the research; if DCA appears to be an avenue worth pursuing its clinical trials group may facilitate the launch of a carefully designed trial.
Michelakis, who is travelling in Europe and unavailable for comment, is said to be distressed that people are taking a drug which could be potentially harmful. In a recent interview with an Edmonton newspaper, he also expressed concern that unauthorized use of DCA could hurt chances to fast-track clinical trials.
Lexchin, who also teaches in York University's school of health policy and management, said Michelakis's concern could be valid.
"If people are already getting access to it and using it in unapproved ways, it could become very difficult to get people to agree to enrol in a clinical trial," he said.
"Because if you are in a clinical trial, you may or may not be getting it (DCA). So why enrol in a clinical trial and take that chance when you can just buy it over the Internet?" _________________ kyranŠ
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