Post-gastric cancer surgery hypophysitis and cortisol insufficiency after immunotherapy: a case series

Abstract Background Gastric cancer is one of the most prevalent and deadly malignancies worldwide. In recent years, with the development of immune checkpoint inhibitors (such as PD-1/PD-L1 and CTLA-4 inhibitors), immunotherapy has emerged as a new strategy in gastric cancer treatment. However, the incidence of immune-related adverse events (irAEs) has also increased. Here, we report eleven cases of gastric cancer patients who developed pituitary or adrenal cortisol insufficiency in the first postoperative week following neoadjuvant immunotherapy. Case presentation We present a retrospective analysis of patients who underwent surgical resection for gastric cancer at our center starting from December 2023. We evaluated their perioperative cortisol function and identified those who developed perioperative cortisol insufficiency, and identified eleven gastric cancer patients with normal cortisol functions who had received neoadjuvant immunotherapy, and subsequently experienced postoperative changes within a short period following surgery. Among them, six patients showed decreased ACTH and cortisol levels, four patients had reduced cortisol levels, and one patient with no ACTH testing also showed reduced cortisol levels. Six patients received hormone replacement therapy, with one developing anastomotic leakage after surgery. Notably, cortisol function was normal in all eleven patients preoperatively. All patients exhibited decreased cortisol function postoperatively, and 27% of them experienced irAE during preoperative treatment. Conclusion This case series is the first in the world that reports on gastric cancer patients who developed pituitary insufficiency or cortisol insufficiency after surgery, potentially linked to the combined effects of immunotherapy and surgery. This series emphasizes the importance of monitoring for immune-related adverse events in patients presenting with symptoms such as fatigue, weakness, and hypotension after surgery. Prompt evaluation of pituitary and adrenal cortical function can reduce the risk of complications associated with postoperative cortisol insufficiency, thereby alleviating patient suffering.