[A Case of MSI-High Testicular Metastasis with Complete Response to Pembrolizumab after Orchiectomy, Which Recurred after Colorectal Carcinoma Resection].

A 74-year-old male was referred to our department for intermittent right abdominal pain that was initially noted 1 month prior. Colonoscopy revealed a type 2 tumor in the ascending colon, for further examination, he was diagnosed with ascending colon cancer(cT4, cN2, cM0). He was performed laparoscopic right hemicolectomy and D3 lymphadenectomy. Subsequently, he received chemotherapy with CAPOX therapy for 8 courses. But right testicular metastasis and bilateral inguinal lymphadenopathy, abdominal para-aortic lymphadenopathy were recurred 18 months after the operation. He was performed right orchiectomy, where the tumor was proved colon cancer with MSI-high. Therefore, he received cancer immunotherapy with pembrolizumab, and got reduction of bilateral inguinal lymph nodes and abdominal para-aortic lymph nodes after 1 month from the start of administration. Now, 28 months later from the start, he maintains complete clinical response(cCR).