Autologous Bone Marrow Transplantation - Blog Science Connections

Treatment Strategies in Breast Cancer 473
cancer disease in comparable terms to those used for marrow transplantation
in leukemia. There are two disease settings in which intensive chemotherapy
regimens for breast cancer is most likely to have a favorable therapeutic-toxic
ratio: 1 ) the high-risk patient with adjuvant disease and 2) the patient who can
be rendered free of disease after development of metastases. The former
situation (the equivalent of first complete remission) can be approached
directly. Patients who are found to have cancerous involvement of 10 or more
lymph nodes at the time of primary surgery for breast cancer have a poor
prognosis despite routine adjuvant chemotherapy. In this setting, the use of
intensive chemotherapy with bone marrow support with or without additional
standard chemotherapy is an attractive and testable therapeutic approach.
The latter situation (treatment of patients rendered disease-free by standard
approaches after first relapse) is more complex and less easily analyzed.
Currently available therapeutic regimens produce complete responses in
only about 7% to 20% of treated patients. This severely limits the applicability
of this approach and would subject patients to induction chemotherapy,
which may produce tumor resistance and host toxicity. Sites of pretreatment
bulk disease will likely require additional surgery or radiation therapy.
Nonetheless, the setting is a frequent clinical problem, and investigation of
intensive therapy approaches is warranted.
The optimal intensive therapeutic program for the treatment of breast
cancer remains to be defined. The availability of multiple non-cross-resistant
agents with nonoverlapping, nonmyelosuppressive toxicities offers the possibility
of constructing novel combination programs. These new regimens
will have to be tested carefully in comparable disease settings to establish the
relative therapeutic efficacy and comparative toxicity of different programs.
With continued study, the toxicity of treatment programs may be reduced
either by development of better supportive care, patient selection, or
modification of the treatment approach.
Bone marrow contamination with malignant cells is likely to be a
frequent problem in breast cancer. The frequency of bone or bone marrow
involvement with neoplasia is in excess of 40%. As therapeutic programs
improve, the likelihood of relapse from contaminated bone marrow will
increase, and laboratory investigations aimed at determining the frequency
and magnitude of malignant involvement are needed.
In summary, high-dose combination alkylating-agent therapy is capable
of producing frequent and rapid complete responses in breast cancer
patients when used as initial chemotherapy for metastases. Systematic,
targeted trials at earlier disease states are the next step in establishing the
value of this approach.