Intensity-modulated proton therapy for elective nodal irradiation and involved-field radiation in the definitive treatment of locally advanced non-small-cell lung cancer: a dosimetric study.

Abstract

BACKGROUND:

Photon involved-field (IF) radiation therapy (IFRT), the standard for locally advanced (LA) non-small cell lung cancer (NSCLC), results in favorable outcomes without increased isolated nodal failures, perhaps from scattered dose to elective nodal stations. Because of the high conformality of intensity-modulated proton therapy (IMPT), proton IFRT could increase nodal failures. We investigated the feasibility of IMPT for elective nodal irradiation (ENI) in LA-NSCLC.

PATIENTS AND METHODS:

IMPT IFRT plans were generated to the same total dose of 66.6-72 Gy received by 20 LA-NSCLC patients treated with photon IFRT. IMPT ENI plans were generated to 46 cobalt Gray equivalent (CGE) to elective nodal planning treatment volumes (PTV) plus 24 CGE to IF-PTVs.

RESULTS:

Proton IFRT and ENI improved the IF-PTV percentage of volume receiving 95% of the prescribed dose (D95) by 4% (P < .01) compared with photon IFRT. All evaluated dosimetric parameters improved significantly with both proton plans. The lung percentage of volume receiving 20 Gy/CGE (V20) and mean lung dose decreased 18% (P < .01) and 36% (P < .01), respectively, with proton IFRT, and 11% (P = .03) and 26% (P < .01) with ENI. The mean esophagus dose decreased 16% with IFRT and 12% with ENI; heart V25 decreased 63% with both (all P < .01).

CONCLUSION:

This study demonstrates the feasibility of IMPT for LA-NSCLC ENI. Potential decreased toxicity indicates that IMPT could allow ENI while maintaining a favorable therapeutic ratio compared with photon IFRT.

• Authors: Aparna H Kesarwala, Christine J Ko, Holly Ning, Eric Xanthopoulos, Karl E Haglund, William P O'Meara, Charles B Simone 2nd, Ramesh Rengan
• Journal: Clinical lung cancer (Clin Lung Cancer) Vol. 16 Issue 3 Pg. 237-44 (May 2015) ISSN: 1938-0690 [Electronic] United States
• PMID: 25604729 (Publication Type: Journal Article, Research Support, N.I.H., Intramural)
• Copyright: Published by Elsevier Inc.

Topics

• Aged
• Carcinoma, Non-Small-Cell Lung (radiotherapy)
• Feasibility Studies
• Female
• Humans
• Lung Neoplasms (pathology, radiotherapy)
• Lymph Nodes (radiation effects)
• Male
• Middle Aged
• Proton Therapy (adverse effects, methods)
• Radiometry
• Radiotherapy Dosage
• Radiotherapy, Conformal (adverse effects, methods)
• Radiotherapy, Intensity-Modulated (adverse effects, methods)
• Tumor Burden