Metastatic Gastric Cancer Causing Severe Hormone-Related Complications

What happened, in summary

A 75-year-old man developed several months of upper abdominal discomfort, poor appetite, and marked weight loss. CT imaging in July 2019 showed an 8 cm abnormal area involving the pylorus and antrum, with large liver deposits and enlarged hepatic and coeliac lymph nodes. Endoscopy found an ulcerating tumor extending through the pylorus into the first part of the duodenum. Biopsy showed moderately to poorly differentiated intestinal-type gastric adenocarcinoma with a focal neuroendocrine component. The tumor was HER2 negative, had a Ki-67 index of 70%, and expressed CD56, synaptophysin, and weak chromogranin.

Two weeks later, he returned with vomiting, profound weakness, fluid overload, and a potassium level of 1.75 mmol/L. Testing confirmed severe excess cortisol driven by ectopic ACTH secretion from the gastric tumor. Potassium replacement, spironolactone, metyrapone, and insulin were used to stabilize the hormone-related complications.

Because the cancer was already widely metastatic, he was not fit for surgery. Six cycles of carboplatin and etoposide were planned, but he received only 3 cycles of carboplatin; etoposide was not started because of his poor general condition. His health continued to decline, with worsening weight loss, appetite, and mobility. Repeat imaging showed larger liver metastases. During a later admission, treatment focused on pain relief and fluids, and he died a few days afterward.