A tiny molecule that's been used for decades to treat other diseases is now looming large as a possibly highly effective treatment for cancer.

DCA, or dichloroacetate, has recently been approved by Health Canada for human trials in the treatment of an advanced form of aggressive brain cancer, and it is currently being prescribed as an "off label" treatment at Medicor Cancer Centre in Toronto for many different forms of cancers, including prostate cancer.

The excitement over DCA began in January 2007, when Dr. Evangelos Michelakis and his colleagues at the University of Alberta published a report in Cancer Cell, showing that DCA caused regression in several cancers, including lung, breast, and brain tumours. Michelakis tested DCA on human cells cultured outside the body and found that only cancer cells were killed, but not the healthy cells. Tumours in rats caused by human cancers also shrank drastically when the rats were fed DCA-laced water for several weeks.

DCA is an odourless, colourless molecule, which has been used for many years to treat metabolic disorders. It has also been tested extensively for toxicity levels in humans, since it is a common by-product of chlorinated water.

For this reason, DCA is considered relatively low in toxicity, so Health Canada approved human trials in September. These will begin immediately with phase II testing on select brain cancer patients. Dr. Michelakis explains that a phase I trial, in which dosages are slowly escalated, would be futile for these patients because of the aggressive nature of their disease.

Even before that testing is fully under way, Medicor Cancer Centre, a private clinic in Toronto, is experimenting with DCA, both alone and in conjunction with other chemotherapies. (The cost of DCA treatment at Medicor is about $160 to $190 per week.) In December 2007, Medicor released a report evaluating the results of DCA treatment on 53 patients, including four with prostate cancer. Sixty-eight percent showed positive results after DCA treatment, including reduction in tumour markers (PSA levels) for at least one prostate cancer patient. Results for other cancers also included reduction in tumour size, improvement in blood tests, symptomatic improvement, and disease stabilization.

Medicor cautions: "We have ... observed positive responses [from DCA treatment] in brain, ovary, prostate and breast cancers; however the numbers are too small to report at this time.... The cancer-specific response rates are not meaningful because of the small number of patients treated so far."

The Medicor report also warns that its data is not from a clinical trial, cannot be generalized, and "should be interpreted with caution." Indeed, the Canadian Cancer Society reminds us that DCA, as a cancer treatment, has not been clinically tested on humans:

DCA must be tested for safety and effectiveness in patients with cancer through an appropriately conducted clinical trial on humans before it should be used by patients. Until these trials take place, the Canadian Cancer Society cannot advise its use by cancer patients.