Intensity-modulated radiotherapy of the prostate after cryotherapy: initial experience.

Objectives: To analyze results of intensity-modulated radiotherapy after cryotherapy ablation for adenocarcinoma of the prostate.

Methods: Patients were either treated adjuvantly after targeted cryotherapy or treated for salvage after local failure of standard whole-prostate cryotherapy. Patients were treated with intensity-modulated radiotherapy to a minimum dose of 73 Gy (mean dose, >75Gy). Prostate-specific antigen (PSA) failure was defined according to the Radiation Therapy Oncology Group-American Society for Therapeutic Radiology and Oncology 2006 consensus definition. Late gastrointestinal and genitourinary toxicity were graded according to the Radiation Therapy Oncology Group late toxicity scale and the Late Effects of Normal Tissue-Subjective, Objective, Management, and Analytic scale.

Results: A total of 16 patients were treated from 1997 to 2007. Three patients were treated adjuvantly, and 13 patients were treated for local failure. The mean pre-cryotherapy PSA value was 8.7 ng/mL. The mean PSA value before irradiation was 6.0 ng/mL. Most patients were intermediate to high risk (8 intermediate risk, 7 high risk). Median follow-up was 33 months. No grade 3 or greater toxicity was seen. Biochemical (PSA) control was achieved in 12 of the 16 patients at last follow-up.

Conclusions: Full-dose intensity-modulated radiotherapy after cryotherapy is well tolerated, without excess late morbidity. This study supports the use of radiation for cryotherapy failure salvage. Furthermore, the combination of cryotherapy and irradiation may be considered in a phase II trial.