Radiat Oncol J.  2023 Dec;41(4):274-282. 10.3857/roj.2023.00773.

Pulmonary function and toxicities of proton versus photon for limited-stage small cell lung cancer

• Seo SH
• Pyo H
• Ahn YC
• Oh D
• Yang K
• Kim N
• Sun JM
• Park S
• Jung HA
• Lee SH
• Ahn JS
• Ahn MJ
• Noh JM

• KMID: 2549376
• DOI: http://doi.org/10.3857/roj.2023.00773

Abstract

Purpose
We aimed to compare the oncological outcomes and toxicities of definitive proton beam therapy (PBT) and photon beam therapy in patients with limited-stage small cell lung cancer (LS-SCLC).
Materials and Methods
We retrospectively reviewed 262 patients with newly diagnosed LS-SCLC who underwent definitive PBT (n = 20; proton group) or photon beam therapy (n = 242; photon group) with concurrent chemotherapy between January 2016 and February 2021 and compared overall survival (OS), progression-free survival (PFS), dose-volume parameters, and toxicities between the groups.
Results
The median follow-up duration was 24.5 months (range, 3.7 to 78.7). Baseline lung function was significantly worse and clinical target volume (CTV) was larger in the proton group (CTV: 296.6 vs. 215.3 mL; p = 0.080). The mean lung V10 was 37.7% ± 16.8% and 51.6% ± 24.5% in the proton and photon groups, respectively (p = 0.002). Two-year OS and PFS rates were 57.2% and 35.7% in the proton group and 65.3% and 40.8% in the photon group, respectively (p = 0.542 and 0.748, respectively). Grade ≥2 radiation pneumonitis and esophagitis occurred in 5 (25.0%) and 7 (35.0%) PBT-treated patients and 66 (27.3%) and 40 (16.5%) photon beam therapy-treated patients, respectively (p = 0.826 and 0.062, respectively).
Conclusion
Although the proton group had poorer lung function and a larger CTV than that in the photon group, both groups exhibited comparable treatment outcomes and radiation-related toxicities in LS-SCLC. PBT may be a valuable therapeutic modality in patients with poor pulmonary function or extensive disease burden owing to its lung-sparing ability.

Keyword

Small cell lung cancer; Proton beam therapy; Radiation therapy