Dosimetric comparison to the heart and cardiac substructure in a large cohort of esophageal cancer patients treated with proton beam therapy or Intensity-modulated radiation therapy

doi:10.1016/j.radonc.2017.07.034

Radiotherapy and Oncology

Volume 125, Issue 1, October 2017, Pages 48-54

https://doi.org/10.1016/j.radonc.2017.07.034 Get rights and content

Abstract

Purpose

To compare heart and cardiac substructure radiation exposure using intensity-modulated radiotherapy (IMRT) vs. proton beam therapy (PBT) for patients with mid- to distal esophageal cancer who received chemoradiation therapy.

Methods and materials

We identified 727 esophageal cancer patients who received IMRT (n = 477) or PBT (n = 250) from March 2004 to December 2015. All patients were treated to 50.4 Gy with IMRT or to 50.4 cobalt Gray equivalents with PBT. IMRT and PBT dose–volume histograms (DVHs) of the whole heart, atria, ventricles, and four coronary arteries were compared. For PBT patients, passive scattering proton therapy (PSPT; n = 237) and intensity-modulated proton therapy (IMPT; n = 13) DVHs were compared.

Results

Compared with IMRT, PBT resulted in significantly lower mean heart dose (MHD) and heart V5, V10, V20, V30, and V40 as well as lower radiation exposure to the four chambers and four coronary arteries. Compared with PSPT, IMPT resulted in significantly lower heart V20, V30, and V40 but not MHD or heart V5 or V10. IMPT also resulted in significantly lower radiation doses to the left atrium, right atrium, left main coronary artery, and left circumflex artery, but not the left ventricle, right ventricle, left anterior descending artery, or right coronary artery. Factors associated with lower MHD included PBT (P < 0.001), smaller planning target volume (PTV; P < 0.001), and gastroesophageal junction (GEJ) tumor (P < 0.001). Among PBT patients, factors associated with lower MHD included IMPT (P = 0.038), beam arrangement other than AP/PA (P < 0.001), smaller PTV (P < 0.001), and GEJ tumor (P < 0.001).

Conclusions

In patients with mid- to distal esophageal cancer, PBT results in significantly lower radiation exposure to the whole heart and cardiac substructures than IMRT. Long-term studies are necessary to determine how this cardiac sparing effect impacts the development of coronary artery disease and other cardiac complications.

Section snippets

Patients

The appropriate institutional review board approved the study. We searched a clinical database of esophageal cancer patients to identify those who received RT with or without surgical resection at our institution between March 2004 and December 2015. Inclusion criteria included pathologic confirmation of mid- to distal esophageal cancer, receipt of chemoradiation therapy using IMRT or PBT with curative intent, completion of a radiation dose of 50.4 Gy or 50.4 cobalt Gray equivalents in 28

Results

A total of 727 patients met the study criteria, including 477 who received IMRT and 250 who received PBT. The patient, tumor, and treatment characteristics are summarized in Table 1. Of the 250 patients who received PBT, 13 received IMPT.

Discussion

To our knowledge, the present study is the first to compare detailed dose distribution to the coronary arteries and chambers of the heart between IMRT and PBT in esophageal cancer patients. Our findings show that compared with IMRT, PBT improved the sparing of normal cardiac structures at almost every dose level. These findings support the use of PBT rather than IMRT in esophageal cancer patients with tumors in the mid- or distal esophagus. The findings of the present study improve our

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Conflicts of interest

SHL has research funding from Elekta, STCube Pharmaceuticals, Peregrine Pharmaceuticals, Hitachi Chemical Inc., and Roche/Genentech, has served as consultant for AstraZeneca. All other authors have no conflicts of interest to declare.

Acknowledgments

The authors would like to thank Joseph Munch from the Department of Scientific Publication, The University of Texas MD Anderson Cancer Center, for reviewing the manuscript.

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Proton therapy in esophageal cancerDosimetric comparison to the heart and cardiac substructure in a large cohort of esophageal cancer patients treated with proton beam therapy or Intensity-modulated radiation therapy

Abstract

Purpose

Methods and materials

Results

Conclusions

Section snippets

Patients

Results

Discussion

Funding

Conflicts of interest

Acknowledgments

Lancet Oncol

Radiother Oncol

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Radiother Oncol

Int J Radiat Oncol Biol Phys

Int J Particle Ther

Proton therapy in esophageal cancer
Dosimetric comparison to the heart and cardiac substructure in a large cohort of esophageal cancer patients treated with proton beam therapy or Intensity-modulated radiation therapy