Salvage proton beam therapy for locoregional recurrence of non-small cell lung cancer

Abstract

Purpose This study aimed to evaluate the clinical outcomes and toxicities of salvage proton beam therapy (PBT) in patients with locoregional recurrent non-small cell lung cancer (NSCLC). Materials and Methods We retrospectively reviewed 53 patients who received salvage PBT for locoregionally recurrent NSCLC between January 2016 and December 2019. The median clinical target volume (CTV) was 71.2 cm 3 (range, 13.3 to 1,200.7 cm 3 ). The median prescribed dose was 64.0 cobalt gray equivalent (CGE) (range, 45.0 to 70.0 CGE). One-third of the patients (32.1%) received concurrent chemoradiotherapy (CCRT). Results The patients’ median age was 67 years (range, 44 to 86 years). The initial treatments were surgery in 31 (58.5%), definitive CCRT in 12 (22.6%), and definitive radiotherapy in 10 (18.9%) patients. The median disease-free interval (DFI) was 14 months (range, 3 to 112 months). Thirty-seven patients (69.8%) had a previous radiotherapy history. Among them, 18 patients (48.7%) had in-field recurrence. The median follow-up time after salvage PBT was 15.0 months (range, 3.5 to 49.3 months). During the follow-up period, 26 patients (49.1%) experienced disease progression: local in 13 (24.5%), regional in 14 (26.5%), and distant metastases in 15 (26.5%). The 2-year overall survival (OS) rate, local control rate, and progression-free survival rate were 79.2%, 68.2%, and 37.1%, respectively. Shorter DFI (≤12 months; p = 0.015) and larger CTV (>80 mL; p = 0.014) were associated with poor OS. Grade 3 toxicities occurred in 8 patients (15.1%): esophagitis in 2, dermatitis in 3, and pulmonary toxicities in 4. Conclusion Salvage PBT for locoregionally recurrent NSCLC was effective, and treatment-related toxicities were tolerable.

Toxicity of Proton Therapy versus Photon Therapy on Salvage Re-Irradiation for Non-Small Cell Lung Cancer

“…However, its outcome is similar to that of conventional RT or IMRT, and some studies have even reported higher toxicity rates of >40% [9]. Previously, our study on salvage PBT including 37 patients who underwent re-RT showed a 2-year OS of 79.2% and a grade 3 or higher toxicity rate of 18.9% [5], which included out-field thoracic recurrences.…”

“…The patients were initially diagnosed with NSCLC and underwent RT with curative intent. The patterns of failure after initial RT were considered as the inclusion criteria and were defined as follows: in-field failure, wherein the geometric center of the recurrent mass is within the 50% isodose line, and marginal failure, wherein it is within 25-50% of the isodose line [5,8]. Moreover, patients who underwent re-RT with curative intent were included in the study.…”

“…RT combined with chemotherapy is the core treatment strategy for locally advanced NSCLC [3,4]. However, after curative treatment, 3-20% of patients experience thoracic recurrence despite the absence of distant metastasis [5]. As a treatment for locoregional recurrence, salvage surgery is recommended for patients with a history of RT.…”

“…However, patients are usually diagnosed with advanced stages or inoperable conditions. In these cases, despite the high risk of treatment-related complications, salvage re-irradiation (re-RT) can be carefully considered [5][6][7].…”

Dosimetry, Efficacy, Safety, and Cost-Effectiveness of Proton Therapy for Non-Small Cell Lung Cancer

“…In addition, proton therapy was tested in a special setting for locally advanced NSCLC, such as salvage, postoperative, or palliative manners. Shin et al [67] retrospectively reviewed 53 patients who received salvage proton therapy for locoregionally recurrent NSCLC, and found that the median disease-free interval was 14 months. The 2-year OS rate, local control rate, and PFS rate were 79.2%, 68.2%, and 37.1%, respectively.…”