The Role of Hypofractionation in Proton Therapy

Abstract

Hypofractionated radiotherapy is an attractive approach for minimizing patient burden and treatment cost. Technological advancements in external beam radiotherapy (EBRT) delivery and image guidance have resulted in improved targeting and conformality of the absorbed dose to the disease and a reduction in dose to healthy tissue. These advances in EBRT have led to an increasing adoption and interest in hypofractionation. Furthermore, for many treatment sites, proton beam therapy (PBT) provides an improved absorbed dose distribution compared to X-ray (photon) EBRT. In the past 10 years there has been a notable increase in reported clinical data involving hypofractionation with PBT, reflecting the interest in this treatment approach. This review will discuss the reported clinical data and radiobiology of hypofractionated PBT. Over 50 published manuscripts reporting clinical results involving hypofractionation and PBT were included in this review, ~90% of which were published since 2010. The most common treatment regions reported were prostate, lung and liver, making over 70% of the reported results. Many of the reported clinical data indicate that hypofractionated PBT can be well tolerated, however future clinical trials are still needed to determine the optimal fractionation regime.

Five-Fraction Proton Therapy for the Treatment of Skull Base Chordomas and Chondrosarcomas: Early Results of a Prospective Series and Description of a Clinical Trial

“…In addition, many patients must travel to access this technology, so reducing the time a patient is away from home and their support network can have significant financial and psychosocial implications. That is why the implementation of hypofractionation within PBRT has gained weight in the last 10 years, increasing the number of publications in this regard, which reflects the interest in this treatment approach [40].…”

Preoperative Dose-Escalated Intensity-Modulated Radiotherapy (IMRT) and Intraoperative Radiation Therapy (IORT) in Patients with Retroperitoneal Soft-Tissue Sarcoma: Final Results of a Clinical Phase I/II Trial

“…Several ongoing trials are investigating different fractionation concepts for extremity and trunk soft-tissue sarcomas [24][25][26]. Particle therapy provides an improved dose distribution with a high dose conformity and reduction in dose to healthy tissue [27]. In analogy to our extremity soft-tissue sarcoma trial, we are currently investigating a hypofractionated particle treatment with carbon ions or protons with 13 fractions of 3 GyRBE single doses in a single-center, randomized, prospective phase II pilot trial for retroperitoneal sarcoma, combining the benefits of reduced organ-at-risk doses of protons or carbon ion with hypofractionation [28,29].…”