Saturday, March 27, 1999
DAVID ROBERTS and SEAN FINE
The Globe and Mail
Tijuana, Mexico and Toronto -- DAVID ROBERTS
in Tijuana, Mexico
Pale, thin and bald, 13-year-old Tyrell Dueck lay in bed yesterday watching television while hooked up to a yellow intravenous bag of laetrile, the widely discredited cancer therapy.
The youngster from Martensville, Sask., is at a Tijuana cancer clinic receiving a grab bag of treatment, including shark cartilage, an untried form of gene therapy, vitamins, enzymes and amino acids.
The boy attracted national attention when a court ordered him to receive conventional treatment against the wishes of his parents. Doctors have since said the cancer has spread to his lungs, and they do not believe they can save him. (Tyrell's father Timothy said earlier this week that the Mexican clinic, American Biologics, has found no sign of cancer in the lungs. But a clinic spokesman said yesterday he believes the cancer is throughout the boy's body. "Cancer is very tricky, there might be a microscopic colony," Mike Culbert said. "He has cancer all over his body.")
Is there anything in the grab bag that could help prolong his life?
Conventional medicine is skeptical. On the other hand, it has yet to entirely reject shark cartilage.
Once seen as promising, shark cartilage is now viewed by some doctors as "the laetrile of the 1990s" -- virtually worthless as a cancer treatment.
But not everyone has given up hope. A Quebec biotechnology company, Aeterna Laboratories, is developing a drug whose main ingredient is a liquid extract of shark cartilage. It will be tested in phase-3 clinical trials on more than 550 patients at 40 hospitals in the United States and Canada, including the Ottawa Regional Cancer Centre. The centre's Dr. William Evans is a principal investigator, along with Dr. Roy Herbst of the world-renowned M. D. Anderson Cancer Center in Houston.
"It has nothing to do with the shark itself -- it's because it's cartilage that it works," Jean-Yves Bourgeois, a spokesman for Aeterna, said yesterday. "The reason that we're using shark cartilage is because it's a convenient and abundant source of cartilage and it's easier to extract cartilage from a shark than from any bovine or poultry source." He is hoping Canadian regulatory authorities will approve the medication as a drug by 2002.
Shark cartilage's history as a cancer treatment dates from 1982, when researchers at the Massachusetts Institute of Technology found it helped inhibit the growth of blood vessels that feed cancerous tumours. That meshed with important work by Dr. Judah Folkman of Harvard University and Dr. Robert Kerbel of Toronto's Sunnybrook Health Sciences Centre, whose theories suggest that cancer tumours can be killed by preventing the growth of blood vessels.
A U.S. chemist, Dr. William Lane, seized on this research and spearheaded research projects in Mexico and Cuba, including one study that purportedly showed a survival rate of nearly 50 per cent after three years among cancer patients previously considered terminal.
But clinical trials so far have found scant effects from the shark cartilage, said Dr. Simon Sutcliffe of the British Columbia Cancer Agency, which takes an official position against use of the material until its benefits have been proven.
"I think the field has been prepared to believe there is a potentially important principle in shark cartilage," but the results have been disappointing, he said.
One study, published recently in the Journal of Clinical Oncology, found that the tumours of 16.7 per cent of patients treated remained stable -- they did not grow -- which is roughly the same effect produced by standard supportive care.
"It's not a decision I would make for my family. I would want to have the benefits of what is known, rather than the benefits of what is not known," Dr. Sutcliffe said.
At the Centre for Integrated Therapy in Vancouver, a complementary cancer centre that gives more weight to anecdotal evidence than conventional medicine, shark cartilage is not offered.
"So far our experience is that there are other things that seem to be more valuable to more people," said Dr. Hal Gunn, a spokesman for the centre, which works alongside traditional treatments of surgery, radiation and chemotherapy.