Background: The selection of treatment for patients with localized prostate cancer requires reliable information about the outcome of conservative management. Previous studies of this question are generally considered unreliable because they were uncontrolled and nonrandomized.
Methods: We performed a pooled analysis of 828 case records from six nonrandomized studies, published since 1985, of men treated conservatively (with observation and delayed hormone therapy but no radical surgery or irradiation) for clinically localized prostate cancer. A Cox regression analysis was performed to determine which factors influenced survival among patients who did not die of causes other than prostate cancer (disease-specific survival). Kaplan-Meier curves for overall and metastasis-free survival among such patients were compared with use of the log-rank method and the Mantel-Haenszel test.
Results: Factors that had a significant effect on disease-specific survival were grade 3 tumors (risk ratio, 10.04), residence in Israel (risk ratio, 2.48) or New York (risk ratio, 0.37), and age under 61 years (risk ratio, 0.32). Ten years after diagnosis, disease-specific survival (with data on men who died from causes other than prostate cancer censored) was 87 percent for men with grade 1 or 2 tumors and 34 percent for those with grade 3 tumors; metastasis-free survival among men who had not died of other causes was 81 percent for grade 1, 58 percent for grade 2, and 26 percent for grade 3 disease. These findings were not affected by the inclusion of men who had early-stage cancer, were older, had worse-than-average health, or underwent delayed radiation therapy or radical prostatectomy.
Conclusions: The strategy of initial conservative management and delayed hormone therapy is a reasonable choice for some men with grade 1 or 2 clinically localized prostate cancer, particularly for those who have an average life expectancy of 10 years or less. New treatment strategies are needed for men with grade 3 prostate cancer.