Clinical Outcomes and Prognostic Factors of High-Dose Proton Beam Therapy for Peripheral Stage I Non-Small-Cell Lung Cancer

Abstract

Background: The efficacy, toxicity, and prognostic factors of high-dose proton beam therapy (PBT) for peripheral stage I non-small-cell lung cancer were assessed in this retrospective study.

Materials and methods: Fifty patients with peripheral stage I non-small-cell lung cancer, two of whom had heterochronic multiple lung cancers, underwent high-dose PBT between January 2009 and September 2014. The relative biological effectiveness of the proton beam was defined as 1.1. The beam energy and spread-out Bragg peak were fine-tuned for the 90% isodose volume of the prescribed dosage to encompass the planning target volume. The cumulative survival curves were calculated using the Kaplan-Meier method. Treatment toxicities were evaluated using version 4 of the Common Terminology Criteria for Adverse Events, version 4.

Results: The study included 35 males and 15 females with a median age of 72.5 years. The median follow-up period was 22.8 months. The clinical stage was IA in 44 (85%) and IB in eight (15%) tumors. The total dose of PBT was 66 GyE in 10 fractions in all tumors. Three-year overall survival rate among all patients was 87.9% (95% confidence interval [CI], 94.8%-73.2%). Forty-five patients were alive, and 5 were dead. Three-year local control and progression-free survival rates were 95.7% (95% CI, 98.9%-83.8%) and 76.3% (95% CI, 86.9%-59.3%), respectively. Only one patient experienced Grade 2 pneumonitis.

Conclusion: High-dose PBT may be an effective and safe treatment option for patients with stage I non-small-cell lung cancer.

Keywords: High-dose; Peripheral lesion; Prognostic factors; Proton beam therapy; Stage I non-small-cell lung cancer.