OLIGOPELVIS 2-GETUG P12- elective nodal radiotherapy for oligorecurrent pelvic/para-aortic nodes in prostate cancer: early toxicity of a randomized phase 3 trial.

PURPOSE: /objective: Limited pelvic/para-aortic nodal relapse of prostate cancer after radical local treatment remains a major challenge for locoregional salvage strategies. Salvage Elective Nodes radiotherapy (ENRT) is an appealing option, but concerns persist regarding its toxicity. This study evaluates the 18-months toxicity profile of salvage ENRT combined with intermittent androgen deprivation therapy (iADT) in patients with pelvic and para-aortic oligometastatic disease, compared with iADT alone.

MATERIAL: /

Methods

OLIGOPELVIS-2/GETUG P12 was a prospective, multicenter, randomized phase III trial. Patients were randomized 1:1 to arm A (6-months iADT alone) or arm B (6-months iADT + ENRT: 54 Gy/1.8 Gy per fraction to the pelvic lymph nodes and 66 Gy/2.2 Gy per fraction to pathological nodes). ENRT started after three months of iADT. After analyzing relapse patterns in the OLIGOPELVIS GETUG P07 study, a December 22, 2021 amendment permitted the inclusion of para-aortic lymph nodes and extended irradiation fields up to the renal arteries. Toxicity was defined using NCI-CTCAE v4.0.

RESULTS

A total of 256 patients were enrolled across 17 French centers between 12/2018 and 05/2023. The safety population included 127 patients in arm A and 121 in arm B. Eight patients in arm B were excluded as they did not ultimately receive radiotherapy. Prior prostate or prostatic bed irradiation was reported in 57% and 55% of patients, respectively. In arm B, 39 patients also received para-aortic irradiation. At 6 months, grade ≥ 2 genitourinary (GU) and gastrointestinal (GI) toxicities occurred in 2.4% vs 9.9% (p = 0.02) and 0% vs 19.8% (p < 0.001) of patients in arms A and B, respectively. At 18 months, grade ≥ 2 GU toxicity was 4.1% vs 10.7%, (p = 0.04) in arms A and B, respectively, while no difference in GI toxicity was observed. Prior prostate or prostatic bed irradiation did not increase toxicity at any time point. Among patients receiving para-aortic irradiation, compared to those without : grade ≥ 2 toxicity was similar at 6 months (GU: 12.8% vs 8.5%, p = 0.8; GI: 20.5% vs 19.5%, p = 0.9), or at 18 months (GU: 10.3% vs 11%, p = 1.0; GI: 0% vs 6.1%, p = 0.17), though 6 months upper grade ≥ 1 GI disorders were more frequent (25.6% vs 9.8%, p = 0.02).

CONCLUSIONS

Eighteen-month toxicity of salvage ENRT with a simultaneous boost to the pathological lymph nodes, associated with 6-months iADT was acceptable, even among patients with prior prostate irradiation or additional para-aortic irradiation (NCT03630666- RCB 2018-A00551-54; FundingPHRC-K 16-129).