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Purpose: The objective of this study was to evaluate adverse events (AEs) in patients who received both immune checkpoint inhibitors and thoracic radiation therapy (RT). In particular, we compared the rate of toxicities of concurrent versus sequential delivery of thoracic RT and checkpoint inhibitors. Methods and Materials: Patient and treatment characteristics were collected on all patients at our institution who were treated with programmed cell death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), and/or cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors and underwent thoracic RT (n = 79). Receiving both treatments within 1 month was considered concurrent (n = 35; 44%), and any treatment up to 6 months apart was considered sequential (n = 44; 56%). The primary endpoint of this study was the rate of Grade ≥2 AEs from combination therapy (immunotherapy and RT), specifically those that are relevant to thoracic RT: Pneumonitis, other pulmonary events, esophagitis, dermatitis, and fatigue. Further univariate analysis was performed to compare AE rates with clinical and therapy-related variables. Results: A total of 79 patients were identified, with lung cancer (n = 45) and melanoma (n = 15) being the most common primary histology. Sixty-two (78%) patients were treated with anti-PD-1 or anti-PD-L1 antibodies, 12 (15%) with anti-CTLA-4 antibodies, and 5 (6%) received both anti-PD-1/PD-L1 and anti-CTLA-4 antibodies. The median follow-up for survivors was 5.9 months (range, 2.4-55.6 months). Grade ≥2 AEs included pneumonitis (n = 5; 6%), esophagitis (n = 6; 8%), and dermatitis (n = 8; 10%). No statistically significant correlation was found between these AEs when comparing concurrent versus sequential treatment. The only significant variable was a correlation of immunotherapy drug category with Grade ≥2 esophagitis (P = .04). Conclusions: Overall, Grade ≥2 AE rates of thoracic RT and immunotherapy appeared as expected and acceptable. The lack of significant differences in AE rates with concurrent versus sequential treatment suggests that even concurrent immunotherapy and thoracic RT may be safe.

Purpose: Brain metastases are common in patients with limited-stage small cell lung cancer (LS-SCLC) due to the inability of most chemotherapeutics to penetrate the blood–brain barrier. Prophylactic cranial irradiation (PCI) is therefore recommended for use in patients with a good response to concurrent chemoradiotherapy. However, PCI is not always delivered; therefore, we investigated the reasons for PCI omission in patients who underwent therapy with curative intent. Methods and materials: We retrospectively reviewed all patients with LS-SCLC who were treated with curative intent at our institution. Overall survival and cumulative incidence of brain metastasis were estimated by the Kaplan-Meier method. The Pearson χ2 test and Mann-Whitney U test were used to examine factors associated with PCI use, and prognostic factors were analyzed with Cox proportional hazards modeling. Results: We examined 208 patients who were treated for LS-SCLC at our institution. A total of 115 patients (55%) received PCI. The most common documented reason for PCI omission was patient refusal due to neurotoxicity concerns (38%). Physician assessment of being medically unfit (33%) and of advanced age (8%) were the second and third most common reasons, respectively. Karnofsky performance status and clinical American Joint Committee on Cancer stage but not PCI were significantly associated with overall survival. Only clinical stage remained an independent factor on multivariate analysis. Conclusions: Approximately half of patients with LS-SCLC ultimately receive PCI, generally for guideline-recommended reasons. The most common reason for PCI omission was patient concerns regarding neurotoxicity. Efforts to decrease PCI neurotoxicity, including hippocampal-sparing radiation and memantine use, may increase the use of this survival-improving intervention in eligible patients with LS-SCLC.