HIGH-DOSAGE chemotherapy treatments are no more effective in treating breast cancer than conventional regimes, according to research by a leading Irish doctor.
The study means women are unlikely to be subjected to the risky treatments that doctors developed in recent years, believing they reduced the likelihood of cancer recurring. High-dose chemotherapy has severe side effects and weakens the immune system, leaving patients at risk of infection.
John Crown, a consultant oncologist at St. Vincent's hospital in Dublin, presented the findings to the European Society for Medical Oncology congress in France last week. Conducted with Professor Robert Leonard, a British-based cancer research specialist, the research took almost six years to complete and has major implications for the future of breast cancer treatment.
"We had great hopes that high-dosage chemotherapy would be better," Crown said. "But at the same time we were developing it, the other treatments got better. High-dose chemotherapy is represented as one of the last hurrahs for chemotherapy, and we hope we will now be looking at more ‘magic bullet' type treatments in the future instead."
The study started in 1995 and involved more than 600 patients in Britain, Ireland, New Zealand and Belgium. Half were randomly selected for high-dosage courses of chemotherapy and the research found there was no significant difference in the outcomes or survival rates between the two groups.
High-dose chemotherapy has grown increasingly common in America as a treatment for breast cancer over the past decade. "The thinking behind it was that if the cancer cell is partially damaged by 2 mg, it might be bumped off if you gave it 20mg,"Crown said.
The aggressive chemotherapy damaged patients' bone marrow, however, preventing the formation of the white blood cells that fight infections in the body. Bone marrow and blood are taken from high-dose patients before treatment and used to boost the immune system during the chemotherapy, though their body's defences remain vulnerable. About 1% of high-dose patients die from the resulting infections.
Breast cancer is the most common form of the disease for women in most western countries. Between 1,800 and 2,000 cases are diagnosed in Ireland every year, and up to 700 women die from it annually.
Titled the Anglo-Celtic I study, Crown and Leonard's research is now likely to end experimentation with high-dose chemotherapy. Brian Moulton, chief executive of the Irish Clinical Oncology Research Group, said: "In America there's a belief that the high dose has a better chance of a cure. The oncologists genuinely believed it was better for their patients, but this was not the case." The paper was one of three given a merit award by the ESMO congress, to which more than 1,000 papers were submitted.