Salvage Reirradiation with Proton Beam Therapy for Locoregionally Recurrent Non-Small Cell Lung Cancer

• Published in: Cancers 2024-10, Vol.16 (21), p.3587
• Main Authors: Ning, Matthew S, Odwuor, Abigael, Chang, Joe Y, Gandhi, Saumil, Liao, Zhongxing, Lin, Steven H, Chen, Aileen, Welsh, James W, Nguyen, Quynh-Nhu, O'Reilly, Michael S, Chun, Stephen G, Bronk, Julianna, Qian, David, Lee, Percy
• Format: Article
• Language: English
• Subjects: Cancer therapies; Care and treatment; Chemotherapy; Development and progression; Dosimetry; Drug dosages; Lung cancer; Lung cancer, Non-small cell; Lung cancer, Small cell; Medical prognosis; Non-small cell lung carcinoma; Patients; Pharmaceutical industry; Planning; Radiation; Radiation therapy; Radiotherapy; Small cell lung carcinoma; Thorax; Tomography; Toxicity
• ISSN: 2072-6694; 2072-6694
• DOI: 10.3390/cancers16213587

This retrospective study evaluates outcomes of 66 patients who underwent reirradiation (re-RT) with proton beam therapy (PBT) for recurrent non-small cell lung cancer. Toxicity was scored via the CTCAE v5.0, and outcomes estimated using the Kaplan-Meier method, with associations evaluated via Cox proportional hazards and logistic regression analyses. Patients were treated to a median re-RT prescription of 66 Gy/33 fxs (BED10 = 79 Gy; IQR: 71-84 Gy) at an interval of 1.4 years from prior RT. Half (50%) received concurrent chemotherapy. At 14 months follow-up, the median OS and PFS were 5 months (95%CI: 13-17) and 12.5 months (95%CI: 10-15), respectively. On multivariable analysis, a higher RT dose (BED10 > 70 Gy) [HR0.37; 95%CI: 0.20-0.68, = 0.001] and concurrent chemotherapy (HR0.48; 95%CI: 0.28-0.81, = 0.007) were associated with improved PFS, while treatment site overlap was adversely associated (HR1.78; 95%CI: 1.05-3.02, = 0.031). The median PFS for definitive RT with concurrent chemotherapy ( = 28), definitive RT alone (BED10 > 70 Gy) [ = 22], and lower prescription RT (BED10 < 70 Gy) [ = 16] was 15.5 months (95%CI: 7.3-23.7), 14.1 months (95%CI: 10.9-17.3), and 3.3 months (95%CI: 0-12.3), respectively (log-rank, = 0.006), with corresponding 2-year estimates of 37% (±9), 18% (±8), and 12.5% (±8), respectively. The incidence of Grade 3+ toxicity was 10.5% (6% pulmonary; 3% esophageal; and 1.5% skin), including one Grade 4 bronchopulmonary hemorrhage but no Grade 5 events. Cases with central site overlap had higher composite Dmax to the esophagus (median 87 Gy [IQR:77-90]), great vessels (median 120 Gy [IQR:110-138]), and proximal bronchial tree (median 120 Gy [IQR:110-138]) as compared to other cases ( ≤ 0.001 for all). However, no significant associations were identified with Grade 3+ events. Thoracic re-RT with PBT is an option for recurrent NSCLC with acceptable outcomes and toxicity for select patients. When feasible, higher prescription doses (BED10 > 70 Gy) should be delivered for definitive intent, and concurrent chemotherapy may benefit individual cases.