No standard treatment exists for prostate cancer pelvic nodal recurrences, metastasis directed therapy (MDT) or elective nodal pelvic radiotherapy (ENRT) being both valid treatment options. In a previous report, we demonstrated that no clinically meaningful differences were observed in worst grade 2 acute gastrointestinal (GI) or genitourinary (GU) toxicity or in QoL subdomains between MDT and ENRT during the first 3 months of follow-up. Here we report the first 24-months late toxicity results of the PEACE V-STORM randomized phase II clinical trial comparing these two treatment modalities.
STORM is an international, phase II, open-label, randomised, superiority trial (NCT03569241). Patients diagnosed with PET-detected pelvic nodal oligorecurrence (≤5 nodes) following radical local treatment for PCa, were randomized in a 1:1 ratio between arm A: MDT and 6 months of ADT, or arm B: ENRT (25×1.8Gy) with MDT and 6 months of ADT. In case of radiotherapy, SBRT (3x10Gy) was used for arm A, with a simultaneous integrated boost in arm B. The primary endpoint is metastasis-free survival and here we report the secondary endpoint of late toxicity, defined as worst grade ≥ 2 Common Terminology Criteria for Adverse Events v4.0 GI and GU toxicity exceeding baseline within 24 months of treatment. Quality of life (QoL) was assessed using the EORTC QLQ C30 and PR25 questionnaires. The Chi-square test was used to compare toxicity between treatment arms.
Between June, 2018 and April 2021, 196 patients were randomly assigned to MDT or ENRT. 97 of 99 allocated to MDT and 93 of 97 patients allocated to ENRT received per-protocol treatment. Worst late grade ≥ 2 GI toxicity was observed in 5.3% of the patients (n=5, grade 2) in the MDT arm vs 6.6% of the patients (n=4, grade 2; n=2, grade 3) in the ENRT arm (p=0.94). Worst late GU toxicity proportions were as follows: grade 2 and 3 events in 18 (19%) and 3 (3.2%) patients in the MDT arm vs 19 (21%) and 5 (5.5%) patients in the ENRT arm (p=0.61). We did not observe a significant difference in the proportion of patients with a clinically meaningful difference in bowel scores between arms for any of the timepoints during the first 2 years.
ENRT and MDT continued to show acceptable toxicity rates during the first 24 months of follow-up, with no clinically meaningful differences in the occurrence of worst grade ≥ 2 GI or GU side effects or decline in bowel QoL scores compared to baseline.