[A Case in Which Pembrolizumab Was Effective for Synchronous Urothelial Carcinoma, Gastric Cancer and Cecal Cancer].

We report a case of urothelial cancer, gastric cancer, and cecal cancer that responded to pembrolizumab treatment. The patient was a 64-year-old man who was diagnosed with invasive urothelial carcinoma. CT scan showed a 9 cm large tumor in the pelvis. GC therapy was started immediately due to the rapid growth. Since the treatment resulted in PD after 6 courses of GC therapy, pembrolizumab chemotherapy was introduced as second-line. After 4 courses of chemotherapy, upper endoscopy showed remnant gastric cancer(0-Ⅱc, tub2)and cecum cancer(Type 1, tub1), but the urothelial cancer treatment was prioritized. After 7 courses of pembrolizumab treatment, pelvic tumor resection was performed. ESD of the residual gastric cancer was scheduled, however the lesion was unclear and could not be confirmed. Ileocecal resection was performed for cecum cancer. Pathology revealed only scars without any cancerous tissue. Based on multiple cancer history and family history, Lynch syndrome was suspected. The patient is still under treatment of pembrolizumab therapy and no recurrence is seen for 4 years.