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The drawbacks of a miracle drug Add to ...

Nathalie Le Prohon was president of Nokia Canada, leading a team of senior executives in 2004, when a tumour the size of a quail egg was found in her breast. When it seemed the news couldn't could get any worse, it did: The cancer had invaded 10 out of 14 lymph nodes.

“My prognosis was a 40 per cent chance of survival for five years,” says the Montreal resident. Her son and daughter were aged 10 and 5 at the time.

A warrior in the executive suite, Ms. Le Prohon soon became one in the cancer ward, too. She pushed for quicker mammograms and more timely chemotherapy. And when she couldn't obtain the latest wonder drug, Herceptin, in Canada, she also pushed to get that funded.

Herceptin had been found, when used with chemotherapy, to halve rates of recurrence within four years of diagnosis for women who have HER-2 (human epidermal growth factor receptor type 2) breast cancer, which affects 20 to 25 per cent of patients. But it came with a not-so-wonderful price tag – roughly $40,000 for a year's worth of treatment.

At the time Ms. Le Prohon needed it, in late spring 2005, only those dying of cancer – not those who potentially could be cured of it – could receive the drug. (Cancer drugs are always tried in metastatic patients first. If the treatment improves survival, it's opened up to those who can be cured.) When she and women like her told their stories, it helped pressure provincial governments to fast-track approval, which came later that year.

Estimates show that since Herceptin was approved for those with potentially curable cancer, hundreds of Canadian women – and thousands across North American – have avoided recurrences each year.

But now, five years later, the researcher who developed this revolutionary drug is suggesting that the way it's currently used in Canada may be doing more harm than good.

California researcher Dennis Slamon developed Herceptin after more than a dozen years pursuing why the HER-2 mutation of breast cancer was particularly difficult to treat. Unlike chemotherapy, which destroys both good and bad cells, Herceptin, a monoclonal antibody, specifically targets the receptor of HER-2 and stops or slows the growth of those cells. A book and movie have depicted his quest.

Today the intense but affable Dr. Slamon is trying to change the behaviour of his fellow oncologists. He says that heart problems detected in some patients during the drug trial, which were expected to fade, turn out to persist when Herceptin is used with a particular kind of chemotherapy.

“It's very controversial,” says the director of clinical and translational research at the Jonsson Comprehensive Cancer Center in Los Angeles. “But I am convinced that we're right and the data support what we say.”

Dr. Slamon says breast-cancer patients are risking heart problems when prescribed a combination of Herceptin and anthracycline chemotherapy – and that they need not be. In his study, one out of 50 patients on that regimen developed congestive heart failure, as compared to one out of 250 when Herceptin was used with non-anthracycline drugs. (Anthracyclines are a type of antibiotic that kills cancer cells by damaging their DNA.)

He says he stopped using the more toxic remedy two-and-a-half years ago and switched to approaches that offer just as good a chance of disease-free survival, but with fewer side effects.

The U.S. Food and Drug Administration seem to agree with his approach. It approved two non-anthracycline treatment plans to be used with Herceptin. Today, an estimated 60 per cent of new patients in the U.S. with potentially curable HER-2 breast cancer (that is, cancer that has not spread) are provided with the new, less-toxic treatment.

In Canada, it's a different story. Many patients may not be given the option. That's because not all oncologists are convinced they should scrap the use of anthracyclines with Herceptin: Some still believe it provides a survival benefit.

In general, doctors are hesitant to switch away from effective treatments until research to the contrary has been printed in peer-reviewed journals. Dr. Slamon has presented his findings to conferences but not yet published.

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