A do-it-yourself cancer treatment that many patients have ordered through the Internet can actually encourage growth in colorectal tumours, researchers at the University of Guelph have found.
Dichloroacetate, or DCA, has been used for years to treat rare metabolic disorders, but became a potential wonder drug three years ago after researchers at the University of Alberta discovered it also offered a new way to target tumour cells. As the scientists scrambled to find money to test DCA in humans, hundreds of patients ordered the white powder over the Internet, ignoring warnings that it might harm them.
A recent study showed it may be effective against brain cancer, but now there's evidence from professor Brenda Coomber and her colleagues in biomedical research at Guelph that it doesn't work against colon cancer.
"It could make things worse, she says.
Dr. Coomber and her colleagues tested the drug in human colon cancer cells as well as in tumours in mice.
Under normal conditions, DCA killed some cancer cells. But when levels of oxygen were reduced, as is often the case in tumours, it was not effective. And in some cases, tumours treated with DCA grew more than those that weren't.
"We are only beginning to tease these things out," Dr. Coomber said. "DCA may well turn out to be an effective treatment in some cases, but it's not necessarily safe in all cases. There are people out there buying this drug off the Internet and self-medicating, [and]note>- who knows what's going on in their tumour. They might actually be making it worse."
Dr. Coomber says she hopes the findings will make cancer patients more cautious about taking DCA.
"Even though it is used to treat people with some metabolic disorders doesn't mean it is harmless."
Getting funding to study DCA is complicated by the fact that it can't be patented as a new drug because it's been around for three decades.
After the University of Alberta's Evangelos Michelakis discovered that it shrank several types of tumours in rats without harming healthy tissue, he couldn't get any pharmaceutical companies to invest the money needed to bring it to market as a cancer treatment. The university raised $200,000 to do the small trial with patients who had an aggressive form of brain cancer.
At the time of the initial discovery, Dr. Michelakis said: "This is the Holy Grail of cancer therapeutics - how to kill cancer cells and spare normal ones."
Conventional chemotherapy targets fast-growing cells and kills both cancerous and normal tissue, which is why patients often loose their hair and suffer other debilitating side effects.
It also held the promise of treating many different types of cancer because it exploits a metabolic pathway common to most cancerous cells.
"The bottom line is that cancer is not a single disease, so it's unrealistic to expect a single drug to be a 'magic bullet' that's effective against every type of cancer," Dr. Coomber says.
She and colleagues Siranoush Shahrzad , Kristen Lacombe, Una Adamcic and Kanwal Minhas published their findings this month in the journal Cancer Letters.
Dr. Michelakis and his colleagues have stressed that patients should not self-medicate with DCA. They have warned that DCA ordered over the Internet may contain dangerous impurities and is often sold in a highly acidic form that could cause "catastrophic" complications. It also could interact with other drugs patients are taking to treat cancer.