Aim: This study evaluated the frequency and long-term dynamics of early and late post irradiation damage after proton-photon or photon therapy for locally advanced prostate cancer.
Background: The results of a randomized study of proton-photon or photon therapy using several fractionation regimes were analyzed in 272 patients with high and intermediate risk of progression.
Materials and methods: Three variants of proton boost fractionation were studied sequentially: 3.0 (8 daily fractions), 4.0 (5 fractions, 3 or 5 fractions/week), and 5.5 (3 fractions, 3 fractions/week) Gy(RBE).
Results: A significant decrease in the severity of both acute and late gastrointestinal injuries is achievable with a proton beam. The dynamics of late gastrointestinal and genitourinary toxicity over a 10-year period were generally characterized by a decrease in severity of morbidity by 30% and 15%, respectively.
Conclusions: Local irradiation with a fractional dose of 3.0-5.5 Gy(RBE) and a cumulative dose of 28.0-28.8 Gy(RBE) for protons significantly reduces the early and late rectitis severity, but does not reduce the risk of lower urinary tract injuries. Fractionation regimens do not significantly differ in toxicity levels.
Keywords: Hypofractionation; Prostate cancer; Protons; Radiation therapy; Toxicity.