Initial experience and patient tolerance of proton stereotactic body radiotherapy

Naba Ali; Jun Zhou; Bree R Eaton; Jeffrey M Switchenko; Yichun Cao; William A Stokes; Pretesh R Patel; Katja M Langen; Roelf Slopsema; Jeffrey D Bradley; Mark W McDonald

Initial experience and patient tolerance of proton stereotactic body radiotherapy

J Radiosurg SBRT. 2024;9(2):121-128.

Authors

Affiliations

¹ Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, GA, USA.
² Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, GA, USA.

PMID: 39087059
PMCID: PMC11288653 (available on 2025-01-01)

Abstract

Purpose: To review our initial experience with proton-based SBRT to evaluate the planning outcomes and initial patient tolerance of treatment.

Patients and methods: From Sep. 2019 to Dec. 2020, 52 patients were treated with proton SBRT to 62 lesions. Fractionation varied by indication and site with a median of 5 fractions and median fractional dose of 8 Gy. Planning outcomes, including plan heterogeneity, conformity, and PTV volume receiving 100% of the prescription dose (PTV V100%) were evaluated. Acute toxicities were prospectively recorded, and patient reported outcomes were assessed prior to and at completion of treatment using the MD Anderson Symptom Inventory (MDASI) and EQ-5D5L visual analogue score (VAS).

Results: All treated patients completed their course of proton-based SBRT. The mean conformity index was 1.05 (range 0.51-1.48). R50% values were comparable to ideal photon parameters. PTV V100% was 89.9% on average (40.44% - 99.76%). 5 patients (10%) required plan modification due to setup or tumor changes. No patients developed a new grade 3 or greater toxicity during treatment. Comparing pretreatment to end of treatment timepoints, there was a significant improvement in the mean VAS (65 to 75, p = 0.014), with no significant change in the mean MDASI symptom (1.7, 1.8; p = 0.79) or interference (2.3, 2.4; p = 0.452) scores.

Conclusion: Proton-based SBRT can achieve dosimetric goals required by major clinical photon trials. It was well-tolerated with no decrement in patient reported outcomes and a mean 10-point improvement in VAS at the conclusion of SBRT. Further follow-up is necessary for tumor control and late effects analysis.

Keywords: proton therapy; stereotactic ablative body radiotherapy (SABR); stereotactic body radiotherapy (SBRT).