Stereotactic Re-Irradiation for Local Recurrence after Radical Prostatectomy and Radiation Therapy: A Retrospective Multicenter Study

SIMPLE SUMMARY: Stereotactic body radiation therapy remains an understudied treatment option for local recurrence in the prostate bed after prostatectomy followed by radiation therapy. Ablative treatment of local recurrence could avoid or delay androgen deprivation therapy or next-generation antiandrogens. This study suggests that this treatment modality could be a valuable option if confirmed by a prospective study, but long-term toxicity may be a significant limitation. ABSTRACT: Prostate cancer recurrence in patients previously treated with radical prostatectomy and radiation therapy is challenging. Re-irradiation could be an option, but data regarding efficacy and safety are lacking. We retrospectively evaluated salvage re-irradiation for local recurrence after prostatectomy and external beam radiation therapy. We collected data from 48 patients who underwent salvage reirradiation with stereotactic radiation therapy for local prostate cancer recurrence in the prostatic bed at four French centers. Fifteen patients (31%) were on androgen deprivation therapy during stereotactic radiotherapy. Biochemical response and relapse-free survival were analyzed, and post-treatment toxicities were assessed according to the Common Terminology of Adverse Events criteria. Five patients had grade 3 late bladder toxicity (cystitis), three had grade 3 late incontinence, and one had grade 3 late chronic pain. At three months, 83% of patients had a positive biochemical response. The median follow-up was 22 months. At the end of the follow-up, 21 patients (43%) had a biochemical relapse. The median time to biologic relapse was 27 months. The biochemical relapse rates at 1 and 2 years were 80% and 52%, respectively. In conclusion, salvage re-irradiation for recurrent prostate cancer in the prostate bed may generate significant toxicity rates, and a prospective study with appropriate patient selection is needed to evaluate its effectiveness.