PARIS--Although well over 1,000 patients with breast cancer are now registered with the North American Autologous Bone Marrow Transplant Registry each year, it is still unclear whether these women actually have something to gain in the long run from dose-intensified regimens, Dr. Gabriel Hortobagyi, of M.D. Anderson Cancer Center, said at the Sixth International Congress on Anti-Cancer Treatment (ICACT).
"Although preliminary results are encouraging," Dr. Hortobagyi said, "there is insufficient evidence to show that high-dose chemotherapy is better than standard-dose chemotherapy for either metastatic or high-risk primary breast cancer."
While acknowledging that there are strong and compelling reasons to believe that dose-intensive chemotherapy correlates with improved response rates and cure rates, Dr. Hortobagyi said that this does not hold true for all cytotoxic drugs.
For example, he noted, the difference between high-dose and low-dose 5-fluorouracil is much more modest than the difference between high-dose and low-dose doxorubicin(Drug information on doxorubicin). "For many drugs, dose intensity might be an important consideration, but for others it is irrelevant to clinical treatment," he said.
High-dose regimens yield complete response rates on the order of 50% in metastatic breast cancer, but these responses tend to be short-lived, with only about 15% to 20% of women remaining free of disease after 3 to 4 years.
"There may be a small minority of women who do derive long-term benefit," Dr. Hortobagyi said. "The question is, what is the real fraction of patients that benefit, and is this comparable to standard chemotherapy?"
Dr. Hortobagyi pointed out that most trials of high-dose chemotherapy have restricted enrollment to women under the age of 62 with high performance status and limited comorbidity. He explained that the age requirement alone will disqualify half of women with metastatic breast cancer while the other exclusion criteria will leave no more than a third of patients eligible.