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
"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. "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.