Purpose: We reviewed our institution's experience treating patients with nonpalpable PSA-detected prostate cancer with three-dimensional conformal radiation therapy (3DCRT) to determine prognostic factors that predict for biochemical-free survival (bNED) control and present the bNED control rates.
Methods and materials: Between May 1, 1990 and November 30, 1994, 160 patients with nonpalpable PSA-detected prostate cancer received 3DCRT at Fox Chase Cancer Center (median total dose 73 Gy; range: 67-78 Gy). bNED failure was defined as three consecutive increases in posttreatment PSA after achieving a nadir. bNED failure was recorded as the time midway between the nadir and the first consecutive rising PSA. Five-year actuarial rates of bNED control were calculated for pretreatment PSA (0-9.9 vs. 10-19.9 vs. > or = 20 ng/ml), Gleason score (2-6 vs. 7-10), treatment field size (prostate vs. small pelvis), age (<65 vs. > or = 65), and dose (< or = 73 vs. >73 Gy) using Kaplan-Meier methods and compared using the Log rank test. The Cox model was used to multivariately establish independent predictors based on significant univariate factors. Median follow-up was 39 months (range: 2-84 months).
Results: The 5-year actuarial rate of bNED control was 86% for the entire group of patients. The Cox Proportional Hazards model demonstrated that pretreatment PSA was an independent predictor of bNED control. Treatment field size was marginally predictive. There was no difference in bNED control when patients were stratified by the number of lobes positive for disease. Statistically different rates of bNED control were seen when the patients with nonpalpable disease were univariately compared to T2b and T2c patients. Three patients experienced Grade 3-4 genitourinary (GU) toxicity and 3 patients experienced Grade 3-4 gastrointestinal (GI) toxicity.
Conclusions: Patients with nonpalpable PSA-detected prostate cancer can be effectively treated with 3DCRT with minimal morbidity and high rates of bNED control at 5 years. Pretreatment PSA level is an independent predictor of bNED control.