Salvage Stereotactic Body Radiation Therapy for Locally Recurrent Prostate Cancer: Quality-of-Life Outcomes From a Prospective Clinical Trial.

[PURPOSE] Salvage stereotactic body radiation therapy (SBRT) for intraprostatic recurrence of prostate cancer is under study in early-phase clinical trials. Presently, the impact of this treatment on toxicity and health-related quality of life (HRQOL) is poorly defined. To our knowledge, we present the first report in the literature of HRQOL and psychometric outcomes from a mature, prospective clinical trial.

[METHODS AND MATERIALS] NCT03253744 was a phase 1 trial of focal salvage SBRT to doses of 40.0 to 42.5 Gy with target volume delineation guided by F-DCFPyL positron emission tomography/computed tomography and magnetic resonance imaging. Secondary endpoints included longitudinal assessment of National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0 adverse events (AEs) and corresponding patient-reported outcome measures (PROMs). PROMs included the Expanded Prostate Cancer Inventory Composite (EPIC)-26, American Urologic Association Internal Prostate Symptom Score, Sexual Health Inventory for Men, Patient-Reported Outcomes Measurement Information System (PROMIS) Anxiety, PROMIS Depression, and PROMIS Psychosocial Illness Impact-Positive. Study assessments were conducted at baseline, 1 month, and at every 3-month interval post-SBRT until study completion or biochemical failure.

[RESULTS] Seventeen participants underwent salvage SBRT and were observed for a median of 24 months (min-max: 18-24 months). Toxicity assessment was completed in all participants, and the HRQOL response rate was 91%. Genitourinary (GU) toxicity was more common than gastrointestinal toxicity with a 24-month cumulative incidence of G2+ AEs of 76.5% (95% CI, 44.6%-90.0%) versus 29.4% (95% CI, 4.1%-48.1%) and G3+ AEs of 11.8% (95% CI, 0.0%-25.8%) versus 5.9% (0.0%-16.4%). GU toxicity peaked at 12 to 15 months and was associated most strongly with urethral reirradiation dose. PROMs were concordant with AEs, with significant differences from baseline noted in the American Urologic Association symptom index, EPIC GU irritation, and EPIC GU incontinence scores at 3 to 6 months, 6 to 9 months, and 9 to 18 months, respectively. No significant differences were noted in gastrointestinal PROMs or PROMIS measures.

[CONCLUSIONS] Salvage SBRT has a favorable treatment-related toxicity and HRQOL profile. Primarily, GU toxicities were observed corresponding to decrements in PROMs.