Clival skull-base metastasis during treatment for Stage IV gastric cancer

What happened, in summary

A 73-year-old man had HER2-negative gastric cancer in the cardia with invasion toward the lower esophagus, ascites and peritoneal dissemination, making the disease Stage IV. He first received S-1 plus oxaliplatin and had a partial response, followed by about 6 months of S-1 maintenance. Ramucirumab plus paclitaxel was then used for another 6 months.

Nivolumab became his third-line treatment. After 6 cycles, imaging showed new disease in a left cervical lymph node, the left pelvic bone and the lung. Radiation was given to the painful pelvic bone metastasis. Nivolumab continued because other disease indicators improved, and after 12 cycles the primary tumor had shrunk. In total, he received 28 cycles over roughly a year before the stomach tumor began growing again.

He later developed a persistent occipital headache, tongue deviation and difficulty speaking. Brain imaging did not show a stroke or brain metastasis, but contrast MRI identified a mass in the clivus at the skull base involving the hypoglossal canal. It was diagnosed as a gastric-cancer metastasis. Palliative radiation improved his headache and tongue deviation. When the primary tumor continued to enlarge, treatment moved to trifluridine/tipiracil. At publication he was alive, his neurologic symptoms had not recurred, and there had been no further disease progression for 6 months after the clival event.