The phase III OLIGOPELVIS 2–GETUG P12 trial provides early safety data for salvage elective nodal radiotherapy combined with intermittent androgen deprivation therapy in patients with oligorecurrent pelvic or para-aortic nodal prostate cancer.
The findings suggest that elective nodal radiotherapy with a simultaneous boost to PET-positive lymph nodes has an acceptable 18-month toxicity profile, including among patients who had previously received prostate or prostate-bed radiotherapy and those requiring para-aortic irradiation.
Why This Study Matters
Oligorecurrent nodal prostate cancer represents a challenging clinical setting between localized disease and widespread metastasis.
Modern PSMA and choline PET imaging can identify small-volume nodal recurrences earlier, creating opportunities for salvage local treatment. However, the optimal strategy remains uncertain.
Metastasis-directed therapy can treat only visible lesions, while elective nodal radiotherapy targets both detectable disease and surrounding lymphatic regions that may contain microscopic cancer.
The potential benefit of this broader approach must be balanced against gastrointestinal and genitourinary toxicity, especially because many patients have already received radiotherapy as part of their initial treatment.
Trial Design
OLIGOPELVIS 2–GETUG P12 was a prospective, multicenter, randomized phase III trial conducted across 17 French centers.
A total of 256 patients with fewer than five PET-positive pelvic or para-aortic lymph nodes were randomized to receive either six months of intermittent androgen deprivation therapy alone or the same hormonal treatment combined with elective nodal radiotherapy.
Radiotherapy consisted of 54 Gy in 30 fractions to the elective pelvic nodal volume, with a simultaneous boost to 66 Gy in 30 fractions for pathological lymph nodes.
Radiotherapy began after three months of hormonal therapy.
Following a protocol amendment, patients with para-aortic nodal recurrence could also be included, with treatment fields extended up to the renal arteries.
Study Population
The safety analysis included 127 patients treated with hormonal therapy alone and 121 patients who received hormonal therapy plus radiotherapy.
More than half of the patients in both arms had previously received radiotherapy to the prostate or prostate bed.
Among patients receiving elective nodal radiotherapy, 39 also underwent para-aortic irradiation.
The majority of recurrences were detected using choline PET, while 28% were identified with PSMA PET.
Six-Month Toxicity
At six months, grade 2 or higher genitourinary toxicity occurred in 2.4% of patients receiving hormonal therapy alone and 9.9% of those receiving radiotherapy.
Grade 2 or higher gastrointestinal toxicity was reported in no patients in the hormonal therapy group and 19.8% of patients in the radiotherapy group.
Most toxicities were low grade.
Diarrhea was the most common gastrointestinal event, while urinary symptoms were mainly irritative or obstructive.
Two patients in the radiotherapy group experienced grade 3 diarrhea. No grade 3 genitourinary toxicity or grade 4 toxicity was reported at this time point.
Eighteen-Month Toxicity
At 18 months, grade 2 or higher genitourinary toxicity remained higher in the radiotherapy group at 10.7%, compared with 4.1% in the hormonal therapy-only group.
However, there was no significant difference in grade 2 or higher gastrointestinal toxicity.
Grade 1 gastrointestinal toxicity decreased over time after the acute treatment period, suggesting that many bowel-related effects were temporary.
Urinary toxicity appeared more persistent, with irritative urinary symptoms and urinary incontinence occurring more frequently in patients who received elective nodal radiotherapy.
Only one grade 3 gastrointestinal event and one grade 3 genitourinary event were observed in each relevant group. No grade 4 toxicities were reported.
Previous Radiotherapy Did Not Increase Severe Toxicity
One of the most clinically relevant findings was that previous prostate or prostate-bed radiotherapy did not significantly increase grade 2 or higher gastrointestinal or genitourinary toxicity.
This is important because more than half of the patients receiving elective nodal radiotherapy had already undergone irradiation during their initial prostate cancer treatment.
Careful cumulative dose assessment was required to reduce overlap between previous fields and recurrent nodal targets.
These findings suggest that salvage nodal radiotherapy may remain feasible after prior irradiation when treatment is carefully planned and organ-at-risk constraints are prioritized.
Para-Aortic Irradiation
The analysis also included 39 patients who received para-aortic nodal irradiation.
Grade 2 or higher genitourinary and gastrointestinal toxicity rates were similar between patients treated with and without para-aortic irradiation at both six and 18 months.
At six months, grade 1 or higher upper gastrointestinal toxicity was more frequent with para-aortic treatment, occurring in 25.6% compared with 9.8% without para-aortic irradiation.
This difference was mainly driven by temporary symptoms such as nausea and was no longer observed at 18 months.
Only one patient developed acute grade 3 diarrhea after para-aortic irradiation.
These early results are encouraging, although the relatively small number of patients requires cautious interpretation.
Clinical Meaning
The study supports the feasibility of a comprehensive nodal salvage strategy that goes beyond treatment of visible lesions alone.
Elective nodal radiotherapy was associated with increased gastrointestinal and genitourinary toxicity, particularly during and shortly after treatment. However, severe toxicity was uncommon, gastrointestinal effects generally decreased over time, and no grade 4 events were reported.
The findings are especially relevant for patients with prior prostate irradiation or para-aortic nodal recurrence, two groups for whom prospective safety data have been limited.
Limitations
This report focuses only on toxicity and does not yet provide the trial’s primary efficacy outcome.
Longer follow-up is required to assess late bowel, urinary, renal, hematologic, and sexual toxicity.
The para-aortic subgroup was relatively small because these patients were included only after a protocol amendment.
The trial also did not include a detailed dose-volume histogram analysis, which could have helped clarify the relationship between radiation exposure and specific adverse effects.
Quality-of-life findings will be reported separately.
Clinical Takeaway
The early OLIGOPELVIS 2–GETUG P12 findings suggest that salvage elective nodal radiotherapy combined with six months of intermittent androgen deprivation therapy has an acceptable 18-month toxicity profile in patients with oligorecurrent nodal prostate cancer.
Although gastrointestinal and genitourinary toxicity increased with radiotherapy, severe events were uncommon.
Previous prostate irradiation did not appear to increase clinically significant toxicity, and additional para-aortic irradiation was not associated with excess grade 2 or higher toxicity.
The final value of this approach will depend on whether the broader nodal treatment improves disease control enough to justify the additional treatment burden.
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