CONFORMAL TECHNIQUE DOSE-ESCALATION FOR PROSTATE-CANCER - BIOCHEMICAL-EVIDENCE OF IMPROVED CANCER CONTROL WITH HIGHER DOSES IN PATIENTS WITH PRETREATMENT PROSTATE-SPECIFIC ANTIGEN GREATER-THAN-OR-EQUAL-TO-10 NG ML/

Purpose: Conformal radiation technology results in fewer late complica tions and allows testing of the value of higher doses in prostate canc er. Methods and Materials: We report the biochemical freedom from dise ase (bNED) rates (bNED failure is Prostate Specific Antigen (PSA) grea ter than or equal to 1.5 ng/ml and rising) at 2 and 3 years for 375 co nsecutive patients treated with conformal technique from 66 to 79 Gy. Median follow-up was 21 months. Biochemical freedom from disease was a nalyzed for patients treated above and below 71 Gy as well as above an d below 73 Gy. Each dose group was subdivided by pretreatment PSA leve l (<10, 10-19.9, and greater than or equal to 20 ng/ml). Dose was stat ed to be at the center of the prostate gland. Results: There was signi ficant improvement in bNED survival for all patients divided by a dose above or below 71 Gy (p = 0.007) and a marginal improvement above or below 73 Gy (p = 0.07). Subdividing by pretreatment PSA level showed n o benefit to the PSA <10 ng/ml group at the higher dose but there was a significant improvement at 71 and 73 Gy for pretreatment PSA 10-19.9 ng/ml (p = 0.03 and 0.05, respectively) and for pretreatment PSA grea ter than or equal to 20 ng/ml (p = 0.003 and 0.02, respectively). Conc lusions: Increasing dose above 71 or 73 Gy did not result in improved bNED survival for patients with pretreatment PSA <10 ng/ml at 2 or 3 y ears. Further dose escalation studies may not be useful in these patie nts. A significant improvement in bNED survival was noted for patients with pretreatment PSA greater than or equal to 10 ng/ml treated above 71 or 73 Gy; further dose escalation studies are warranted.