This is important because the optimal duration of chemotherapy treatment for advanced prostate cancer is unknown. In many studies of newer chemotherapy drugs, patients are treated either for a fixed number of treatment cycles or until the disease progresses or until the side effects become intolerable. For patients who are responding to the chemotherapy, however, continuous chemotherapy may be exposing them to unnecessary toxicity.
"More than one-third of advanced prostate cancer patients complete their first round of chemotherapy with the disease in control," said Tomasz Beer, M.D., director of the prostate cancer program in the OHSU Cancer Institute. "Indefinite chemotherapy is not practical because toxicity and side effects accumulate, so we wanted to find out if a patient can take breaks -- or 'holidays' -- in chemotherapy and then be retreated with the same chemotherapy."
Beer and his colleagues found that when treatment was restarted after a chemotherapy holiday, roughly three-quarters of study subjects responded again or experienced stabilized prostate-specific androgen (PSA), a protein made only by prostate cells that is monitored to help predict the presence and progression of prostate cancer. The median duration of the first chemotherapy holiday was 16 weeks.
"This was a clinically meaningful break for most of the subjects," Beer said. Prostate cancer is the most common malignancy among men and the second leading cause of cancer death in men in the United States. One in six American men will develop prostate cancer during his lifetime.
Beer will present initial results on intermittent chemotherapy for metastatic prostate cancer from the AIPC Study of Calcitriol Enhancing Taxotere (ASCENT) on Sunday, June 4, at the 2006 annual meeting of the American Society for Clinical Oncology.