[Unresectable advanced gastric cancer in which tumor shrinkage persisted for a long period even after the discontinuation of nivolumab third-line treatment due to immune-related adverse events:a case report].

Abstract

A 77-year-old man with unresectable advanced gastric cancer, complicated by multiple liver and distant lymph node metastases, began drug therapy. As a third-line treatment, nivolumab was administered for two courses;however, the patient developed destructive thyroiditis. Treatment with nivolumab was resumed after clinical improvement, but the patient developed interstitial pneumonia following a total of four courses, leading to discontinuation of treatment. Although nivolumab was discontinued and no further drug therapy was initiated, tumor shrinkage persisted for 15 months. Notably, the metastatic lesions remained stable and the tumor markers had not increased even 29 months later. The patient's clinical course differed from that typically observed in patients treated with conventional cytotoxic agents, as tumor shrinkage continued long after the discontinuation of nivolumab.