Salvage Stereotactic Body Radiation Therapy for Local Prostate Cancer Recurrence After Radiation Therapy: A Retrospective Multicenter Study of the GETUG.

PURPOSE: To assess the efficacy and safety of salvage stereotactic body radiation therapy (SBRT) in patients with biopsy-proven local prostate cancer recurrence after radiation therapy. METHODS AND MATERIALS: Between April 2010 and January 2017, 100 patients were included in 7 centers. Disease extension was assessed by pelvic multiparametric magnetic resonance imaging and choline positron emission tomography in 87% and 94% of patients, respectively. The median time interval between the 2 treatments was 7.5 years (range, 2-18). Median prostate-specific antigen at recurrence was 4.3 ng/mL (range, 2-38). Median SBRT dose was 36 Gy (range, 25-36.25) in 6 fractions (range, 5-6), every other day. Thirty-four percent of patients were treated by androgen deprivation therapy for a median duration of 12 months. Toxicity was assessed according to Common Terminology Criteria for Adverse Events version 4.03. RESULTS: Median follow-up was 29.3 months (range, 4-91). Second biochemical recurrence-free survival rate at 3 years was 55% (95% confidence interval [CI], 42%-66%). The initial D'Amico group, time interval after first radiation therapy, and SBRT dose were prognostic factors of biochemical recurrence-free survival in multivariate analysis (P = .09, P = .025, P = .018, respectively). No patient developed acute gastrointestinal toxicity of grade >1; rates of acute genitourinary toxicity of grade 2 and 3 were 8% and 1%, respectively. The actuarial 3-year grade ≥2 genitourinary and gastrointestinal toxicity was 20.8% (95% CI, 13%-29%) and 1% (95% CI, 0.1%-5.1%), respectively. One patient presented with neuritis of grade 3. CONCLUSIONS: With a short follow-up, this study shows that salvage SBRT allows for encouraging control and acceptable toxicity. Further prospective studies are necessary to confirm these preliminary results and to determine late toxicity.

Intensity-modulated radiotherapy for prostate cancer with seminal vesicle involvement (T3b): A multicentric retrospective analysis.

OBJECTIVES: No study has reported clinical results of external-beam radiotherapy specifically for T3b prostate cancer. The possibility of escalating the dose to the involved seminal vesicles (ISV) while respecting the dose constraints in the organs at risk is thus so far not clearly demonstrated. The objective of the study was to analyze the dose distribution and the clinical outcome in a large series of patients who received IMRT for T3b prostate cancer. MATERIALS AND METHODS: This retrospective analysis included all patients who received IMRT and androgen deprivation therapy for T3b prostate cancer, between 2008 and 2017, in six French institutions, with available MRI images and dosimetric data. RESULTS: A total of 276 T3b patients were included. The median follow-up was 26 months. The median (range) prescribed doses (Gy) to the prostate and to the ISV were 77 (70-80) and 76 (46-80), respectively. The dose constraint recommendations were exceeded in less than 12% of patients for the rectum and the bladder. The 5-year risks of biochemical and clinical recurrences and cancer-specific death were 24.8%, 21.7%, and 10.3%, respectively. The 5-year risks of local, pelvic lymph node, and metastatic recurrences were 6.4%, 11.3%, and 15%, respectively. The number of involved lymph nodes (≤ 2 or ≥ 3) on MRI was the only significant prognostic factor in clinical recurrence (HR 9.86) and death (HR 2.78). Grade ≥ 2 acute and 5-year late toxicity rates were 13.2% and 12% for digestive toxicity, and 34% and 31.5% for urinary toxicity, respectively. The dose to the pelvic lymph node and the age were predictive of late digestive toxicity. CONCLUSION: IMRT for T3b prostate cancer allows delivery of a curative dose in the ISV, with a moderate digestive toxicity but a higher urinary toxicity. Lymph node involvement increases the risk of recurrence and death.