Comparison of adverse effects of proton and X-ray chemoradiotherapy for esophageal cancer using an adaptive dose–volume histogram analysis

Abstract

Cardiopulmonary late toxicity is of concern in concurrent chemoradiotherapy (CCRT) for esophageal cancer. The aim of this study was to examine the benefit of proton beam therapy (PBT) using clinical data and adaptive dose–volume histogram (DVH) analysis. The subjects were 44 patients with esophageal cancer who underwent definitive CCRT using X-rays (n = 19) or protons (n = 25). Experimental recalculation using protons was performed for the patient actually treated with X-rays, and vice versa. Target coverage and dose constraints of normal tissues were conserved. Lung V5–V20, mean lung dose (MLD), and heart V30–V50 were compared for risk organ doses between experimental plans and actual treatment plans. Potential toxicity was estimated using protons in patients actually treated with X-rays, and vice versa. Pulmonary events of Grade ≥2 occurred in 8/44 cases (18%), and cardiac events were seen in 11 cases (25%). Risk organ doses in patients with events of Grade ≥2 were significantly higher than for those with events of Grade ≤1. Risk organ doses were lower in proton plans compared with X-ray plans. All patients suffering toxicity who were treated with X-rays (n = 13) had reduced predicted doses in lung and heart using protons, while doses in all patients treated with protons (n = 24) with toxicity of Grade ≤1 had worsened predicted toxicity with X-rays. Analysis of normal tissue complication probability showed a potential reduction in toxicity by using proton beams. Irradiation dose, volume and adverse effects on the heart and lung can be reduced using protons. Thus, PBT is a promising treatment modality for the management of esophageal cancer.

Evaluation of plan quality and robustness of IMPT and helical IMRT for cervical cancer

“…Although randomized clinical trials are necessary to confirm whether proton therapy reduces toxicity as compared with photon therapy, it is hard to perform such studies. NTCP modeling analysis is one method to estimate the effectiveness of proton over photon radiotherapy from previous studies [29][30][31]. NTCP of rectum and sigmoid were calculated based on LKB model.…”

NTCP modeling analysis of acute hematologic toxicity in whole pelvic radiation therapy for gynecologic malignancies – A dosimetric comparison of IMRT and spot-scanning proton therapy (SSPT)

“…Jakobi et al conducted in silico study using NTCP modeling analysis in head and neck region to identify patients who may benefit from PBT [31][32][33]. Makishima et al showed that NTCP value for the lung and heart decreased in proton plan compared with photon plan in esophageal cancer [34]. Toramatsu et al showed that large size of hepatocellular carcinoma could be more safely treated with SSPT than IMRT regarding the risk of radiation-induced liver disease using NTCP modeling analysis [35].…”

Proton beam therapy in Japan: current and future status

“…Makishima et al compared the dose distribution of X-ray beam RT and PBT for esophageal cancer patients (53), and found that cardiac and pulmonary toxicities were correlated with the radiation doses to heart and lung. The toxicities could be markedly reduced by the use of PBT, based on analysis using normal tissue complication probability.…”