Long-term survival after resolution of pulmonary metastasis in a patient with unresectable cervical esophageal carcinoma after nivolumab-induced immune-related adverse events.

Nivolumab is a first-line treatment for unresectable esophageal cancer; however, immune-related adverse events (irAEs) can be severe. We report a rare case of long-term survival without chemotherapy after the resolution of lung metastases potentially triggered by a nivolumab-induced irAE. A 70-year-old man with cStage III cervical esophageal squamous cell carcinoma received definitive chemoradiotherapy. One month later, lung and bone metastases were detected. Chemotherapy with fluorouracil and cisplatin was continued, followed by palliative radiotherapy. Although the primary tumor disappeared, the lung metastases progressed, and nivolumab was administered. After a single dose, the patient developed multiple irAEs, including interstitial pneumonia, hypophysitis, and polymyalgia rheumatica. These were managed with corticosteroids. Subsequently, the pulmonary metastases regressed and eventually disappeared. Radiotherapy was also performed for later local recurrences. No further systemic therapy was given, and the patient has remained alive in the 45 months. This case suggests that not only nivolumab-induced immune activation but also multidisciplinary treatment, including chemotherapy and radiotherapy, may contribute to durable tumor control in advanced esophageal cancer.