Study Shows Age Does Not Affect Response to Prostate Cancer
05/31/03 CHICAGO, III.
Chemotherapy is as effective in the elderly as it in younger patients
"This is encouraging news for the elderly. Fear of side effects or diminishing efficacy leads some older patients and their doctors to forego cancer treatment," said Tomasz Beer, M.D., an oncologist at the Oregon Health & Science University (OHSU) Cancer Institute in Portland, Ore., and study co-investigator with William Berry, M.D., of US Oncology.
"Weekly regimens of docetaxel were especially well tolerated by the elderly, with much less risk of some of the more serious toxicities, such as neutropenia, a condition that leaves patients susceptible to serious bacterial infections," Berry said.
Prostate cancer is the most common malignancy among men and the second leading cause of cancer death in men in the United States. Overall, roughly one in six American men will develop prostate cancer during his lifetime.
Increasingly, chemotherapy is the preferred treatment for patients with androgen-independent prostate cancer (AIPC), an advanced stage of the disease reached when the cancer is unresponsive to hormone therapy. Currently docetaxel alone, or in combination with other agents, is the most widely used chemotherapy agent for prostate cancer in the United States. Elderly patients are underrepresented in clinical trials; consequently, relatively little information about the impact of age on efficacy and tolerance of docetaxel is available.
"Yet understanding how aging may interact with the treatment is an especially important issue for patients with prostate cancer because the disease disproportionately effects the elderly," Beer said. The clinical study was conducted retrospectively. Individual patient data were pooled from two phase II clinical trials in which docetaxel (36 mg/m2 ) was administered weekly for six weeks and repeated every eight weeks. The studies involved 86 patients and were conducted at OHSU and US Oncology. The patients' median age was 72, with 34 patients younger than 70 and 52 patients aged 70 and older.
Efficacy of weekly docetaxel was indicated by prostate-specific antigen (PSA) response rate at the start of the study, measurable disease response rate, time to progression and survival. PSA is a protein made only by prostate cells. Certain prostate conditions, including prostate cancer, can cause high levels of PSA in the blood. PSA blood levels are monitored to help predict the presence and progression of prostate cancer.
Toxicity of the chemotherapy treatment was measured by the number of patients who experienced significant toxicities and the average number of distinct toxicity events per patient. Patients were monitored for both hematologic side effects, such as anemia, and for more than 30 other side effects such as fatigue, nausea, dermatitis and weight loss.
After adjusting for baseline PSA measurements and hemoglobin, analysis showed no measurable response differences between the two age groups and no significant differences in monitored toxicity events.
"While the older patients had higher initial baseline PSAs and were a bit more anemic before treatment, their overall outcomes were quite similar to the younger patients," said Beer. "These findings are consistent with the hypothesis that docetaxel chemotherapy is equally well tolerated and equally effective across a wide range of ages in patients with AIPC."
However, due to the small sample size of the study, the analysis does not definitively demonstrate non-inferiority of weekly docetaxel in the elderly, cautioned Beer. These preliminary results should be confirmed in a larger prospective study. "There could be smaller effects not detected in this study that may be clinically significant," Beer said.
The phase II trials were sponsored by Aventis Pharmaceuticals. This analysis was carried out without support. Aventis is dedicated to treating and preventing disease by discovering and developing innovative prescription drugs and human vaccines. Visit http://www.aventis-us.com for more information about Aventis in the United States.
Tomasz M. Beer, M.D., is an assistant professor of medicine (hematology and medical oncology) in the OHSU School of Medicine, and a member of the OHSU Cancer Institute.
William R. Berry, M.D., is an oncologist in private practice in Raleigh, N.C., and co-chairman of US Oncology's Genito-Urinary Cancer Research Committee.