Acute toxicity and quality of life in patients with prostate cancer treated with protons or carbon ions in a prospective randomized phase II study – the IPI trial
Mené sur 92 patients atteints d'un cancer de la prostate de stade localisé (durée médiane de suivi : 22,3 mois), cet essai de phase II compare la faisabilité et la toxicité aiguë de deux types de radiothérapie hypofractionnée, l'une par faisceaux de protons et l'autre par faisceaux d'ions carbone, puis évalue l'effet de ces traitements sur la qualité de vie des patients
Background : To evaluate safety and feasibility of primary hypofractionated raster-scanned irradiation of the prostate with protons and carbon ions in a prospective randomized phase II trial. Methods and Materials : In this trial, 92 patients with localized prostate cancer were enrolled. Patients were randomized either to protons (arm A) or carbon ions (arm B) and treated with a total dose of 66 Gy(RBE) administered in 20 fractions (single dose of 3.3 Gy(RBE). Patients were stratified by the use of antihormonal therapy. Primary endpoint was the combined assessment of safety and feasibility. Secondary endpoints were specific toxicities, PSA-progression free survival (PSA-PFS), overall survival (OS) and quality-of-life (QoL). Results : 91 patients completed therapy with a median follow-up of 22.3 months. Among acute genitourinary toxicities, cystitis rates were 34.1% (A: 39.1%, B: 28.9%) grade 1 and 17.6% (A: 21.7%, B: 13.3%) grade 2. Seven patients (8%) required urinary catheterization during treatment due to urinary retention, of whom five were in arm A. Regarding acute gastrointestinal toxicities, two patients treated with protons developed a rectum fistula of grade 3. Radiation proctitis occurred in 12.1% (A: 13.0%, B: 11.1%) as grade 1 and in 5.5% (A: 8.7%, B: 2.2%) as grade 2. No statistically significant differences in the toxicity profiles regarding both arms were found. QoL was mainly reduced regarding fatigue, pain and urinary symptoms during therapy and six weeks thereafter. All EORTC QLQ-C30 and -PR25 scores improved during follow-up. Conclusion : Hypofractionated irradiation using either carbon ions or protons results in comparable acute toxicities and QoL parameters. We found that hypofractionated particle irradiation is feasible and might be safe. Due to the occurrence of gel in the rectum wall and the consecutive occurrence of two rectal fistulas, we stopped using the insertion of spacer gel. Longer follow-up is necessary for evaluation of PFS and OS.