Purpose Radiation therapy (RT) improves control of Hodgkin lymphoma (HL), but patients who undergo RT are at risk for late effects, including cardiovascular disease and second cancers, because of radiation doses to organs at risk (OARs). Proton therapy (PT) can reduce OAR doses compared with conventional photon RT. However, access to PT is currently limited, so referrals must be appropriately selective. We aimed to identify subgroups of patients with HL who could benefit the most dosimetrically from RT with PT based on the prechemotherapy disease characteristics. Methods and materials Normal tissue radiation doses were calculated for 21 patients with HL who were treated with deep-inspiration breath-hold pencil-beam scanning (PBS) PT and compared with doses from 3-dimensional conformal (3D-CRT) and partial arc volumetric modulated (PartArc) photon RT. Prechemotherapy disease characteristics associated with significant dosimetric benefits from PBS compared with photon RT were identified. Results Treatment with PBS was well tolerated and provided with good local control. PBS provided dosimetric advantages for patients whose clinical treatment volume extended below the seventh thoracic level and for female patients with axillary disease. In addition, an increasing dosimetric benefit for some OARs was observed for increasing target volume. PBS significantly reduced the mean dose to the heart, breast, lungs, spinal cord, and esophagus. Dose homogeneity and conformity within the target volume were also superior with PBS, but some high-dose measures and hot spots were increased with PBS compared with partial arc volumetric modulated photon RT. Conclusions PBS gives good target coverage and local control while providing reductions in radiation dose to OARs for individuals who receive RT for HL compared with advanced photon RT. Our findings highlight groups of patients who would be expected to gain more dosimetric benefit from PBS. These findings facilitate the selection of patients who should be considered a priority for PT.
Introduction Extreme hypofractionated radiotherapy for prostate cancer is a common modality in photon therapy. Pencil beam scanning (PBS) in similar fractionation allows better dose distribution and makes proton therapy more available for such patients. The purpose of this study is the feasibility of extreme proton hypofractionated radiotherapy and publication of early clinical results. Methods Two hundred patients with early‐stage prostate cancer were treated with IMPT (intensity‐modulated proton therapy), extreme hypofractionated schedule (36.25 GyE in five fractions) between February 2013 and December 2015. Mean age of the patients was 64.3 years, and the mean value of prostate‐specific antigen (PSA) before treatment was 6.83 μg/L (0.6–17.3 μg/L). Ninety‐three patients (46.5%) were in the low‐risk group. One hundred and seven patients (53.5%) were in the intermediate‐risk group. Twenty‐nine patients (14.5%) had neoadjuvant hormonal therapy, and no patients had adjuvant hormonal therapy. Acute toxicity, late toxicity and short‐term results were evaluated. Results All patients finished radiotherapy without interruptions. The median follow‐up time was 36 months. The mean treatment time was 9.5 days (median 9 days). Acute toxicity according to Common Terminology Criteria for Adverse Events (CTCAE) v 4.0 was (gastrointestinal toxicity) GI (grade) G1‐17%, G2‐3.5%; (genitourinary toxicity) GU G1‐40%, G2‐19%; and no G3 toxicity was observed. Late toxicity was GI G1‐19%, G2‐5.5%; GU G1‐17%, G2‐4%; and no G3 toxicity was observed. PSA relapse was observed in one patient (1.08%) in the low‐risk group (pelvic lymph node involvement was detected) and in seven patients (6.5%) in the intermediate‐risk group (three lymph node metastases, two lymph node and bone metastases, two PSA relapses). No patient died of prostate cancer, and three patients died from other reasons. No local recurrence of cancer in the prostate was observed. Conclusions Proton beam radiotherapy for prostate cancer is feasible with a low rate of acute toxicity and promising late toxicity and effectivity.
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