OLIGOPELVIS – GETUG P07, a multicentre phase II trial of combined salvage radiotherapy and hormone therapy in oligometastatic pelvic node relapses of prostate cancer: Preplanned analysis of acute toxicity.

173 Background: We explored the role of salvage pelvic radiotherapy combined with LH-RH agonists in pelvic oligometastatic patients (pts) detected by 18F-choline positron-emission tomography (FCH-PET) imaging in biochemically relapsing prostate cancer patients following radical therapy. We report a preplanned analysis of acute toxicity and quality of life after the first 20 pts. Methods: Biochemically relapsing prostate cancer pts with 1-5 FCH-PET positive oligometastatic pelvic lymph nodes received high-dose image-guided intensity-modulated radiation therapy (RT: pelvic lymph nodes 54 Gy, 30 f; FCH-PET-positive lymph nodes 66 Gy, 30 f; prostate bed 66 Gy, 33 f; if FCH-PET-positive prostate bed relapse 72 Gy, 36 f) combined with 6 months LH-RH agonists. Primary objective was biochemical-clinical failure-free survival. After the first 20 pts, a preplanned analysis of toxicity at 1 months after RT completion was conducted. Stopping criteria were more than 10 or 2 pts experiencing grade 2 or 3 toxicity respectively. Changes in toxicity (NCI-CTC AE v4), and quality of life (EORTC QLQ-C30 and PR25 questionnaires) over time were analyzed by the Wilcoxon signed-rank test. Results: 20 pts (median age 62) presenting oligometastatic pelvic lymph nodes (mean 1.7) received RT to lymph nodes in all pts and to the prostate bed in 8 pts with a boost to a local relapse in 2 pts. Grade 2 gastrointestinal and genitourinary toxicity was noted in 4/20 and 0/20 pts respectively during radiotherapy that resolved completely in all pts one month after treatment. No grade 3 toxicity was noted. At 1 month, significant worsening was reported by pts for 4/21 QoL items but the worsening was clinically relevant ( > 10 points) for 2 items only: fatigue and dyspnea. However, there was significant - but clinically non-relevant ( < 10 points) - worsening of physical functioning and hormonal-treatment related symptoms. Conclusions: High-dose RT to the pelvis and oligometastatic lymph nodes did not increase acute toxicity. As per protocol, the study resumed and is now recruiting 50 more patients. Clinical trial information: NCT02274779.