Salvage radiotherapy for prostate cancer recurrence after cryosurgical ablation.

OBJECTIVES: To retrospectively determine the outcome of patients treated with salvage three-dimensional conformal radiotherapy (RT) for prostate cancer recurrence after cryosurgical ablation of the prostate (CSAP). Biochemical control rates and morbidity were analyzed.

METHODS: Between January 1990 and November 1999, a total of 49 patients initially treated with CSAP were later irradiated because of a rising prostate-specific antigen (PSA) level and/or a positive biopsy at Allegheny General Hospital. The clinical stage before cryosurgery was T1c in 7 patients; T2a in 7 patients; T2b in 10 patients; T3 in 17 patients; and T4 and/or N1 in 8 patients. The Gleason score was 6 or lower in 29 patients, 7 in 11 patients, and 8 or higher in 9 patients. The mean pre-CSAP PSA level was 15.7 ng/mL (range 2.4 to 45). One patient had a PSA level less than 4 ng/mL, 16 had a PSA level of 4 to 10 ng/mL, 21 had a PSA level of 10 to 20 ng/mL, and 11 had a PSA level greater than 20 ng/mL. Before the start of RT, a complete restaging workup was performed and was negative for distant metastatic disease in all 49 patients. The mean interval to recurrence after CSAP was 19 months (range 3 to 78). The mean RT dose to the planning target volume was 62.9 Gy (range 50.4 to 68.4).

RESULTS: The mean pre-RT PSA level was 2.4 ng/mL (range 0.1 to 7.4). After RT, the mean nadir PSA level was 0.4 ng/mL (range 0 to 4.2). The mean time to PSA nadir was 5.8 months (range 1 to 15). In 42 patients, the PSA nadir was less than 1.0 ng/mL, in 5 patients the PSA nadir was greater than 1 ng/mL, and in 2 patients the PSA level remained stable. With a median follow-up time of 32 months (range 12 to 85), the overall biochemical control rate was 61%. The mean time to biochemical failure was 14.5 months (range 1 to 47). Of 30 patients with a pre-RT PSA level of 2.5 ng/mL or less, the disease of 22 (73%) was controlled compared with only 8 (42%) of 19 with a pre-RT PSA level greater than 2.5 ng/mL (P = 0.040). Biochemical control occurred in 18 (69%) of 26 patients with a dose of 64 Gy or greater compared with only 12 (52%) of 23 patients with a dose of less than 64 Gy (P = 0.024). The disease of 20 (70%) of 29 patients with a Gleason score of 6 or lower was controlled versus 10 (50%) of 20 patients with a Gleason score of 7 or greater (P = 0.064). Only 2 patients developed subacute morbidity (proctitis and a urethral stricture). All complications resolved with conservative measures.

CONCLUSIONS: Salvage RT for prostate cancer recurrence after CSAP appears feasible. Our preliminary experience revealed that post-CSAP RT in patients with prostate cancer appears to effectively diminish the post-RT PSA level to a nadir of 1.0 ng/mL or less in most patients. The pre-RT PSA level and radiation dose may be important predictors of biochemical control in the salvage setting. RT as described was associated with minimal toxicity to the gastrointestinal/genitourinary systems. Additional prospective randomized studies are necessary to better assess the role of RT in the treatment of these patients.