Stereotactic Body Radiotherapy And Checkpoint Inhibitor For Locally Recurrent Unresectable Nasopharyngeal Carcinoma

The treatment of local recurrence of nasopharyngeal carcinoma (NPC) is challenging, and the role of reirradiation is controversial regarding the high risk for severe toxicity. Stereotactic body radiotherapy (SBRT) is a high-precision radiation technique that can spare surrounding normal tissues. Studies have demonstrated the high activity and low toxicity of both SBRT and anti-programmed-cell-death-1 immune checkpoint inhibitors for head and neck cancers. There has been preclinical and clinical evidence suggesting synergy between radiotherapy and checkpoint inhibitors. We report two patients with locally recurrent unresectable rT4 NPC both involving the retro-orbital areas. They received the same treatment with low-dose SBRT (28 Gy in 5 fractions) and pembrolizumab, and showed a remarkable tumour response without untoward radiation toxicity. SBRT plus an immune checkpoint inhibitor may provide a new treatment option for locally recurrent NPC. We propose further investigation with a formal clinical trial.