[A Case of Metachronous Liver Metastasis That Recurred 15 Years after Surgery for Sigmoid Colon Cancer].

We report a case of metachronous liver metastasis occurring 15 years after surgery for sigmoid colon cancer(SCC). The patient was a 76-year-old male who underwent sigmoid colectomy(D3 lymphadenectomy)for SCC 15 years ago. Pathological examination at that time revealed adenocarcinoma(tub1, pap), pT3, pN0, cM0, pStage Ⅱa. He received adjuvant chemotherapy with S-1 for approximately 1 year postoperatively and was under observation thereafter. After 15 years, the tumor markers CEA and CA19-9 showed elevated levels during follow-up visits with his primary care physician. A CT scan revealed a liver tumor in the lateral segment, and cytological examination via fine-needle aspiration was consistent with findings not contradicting colorectal cancer liver metastasis. Subsequent surgical resection of the liver tumor confirmed pathology consistent with metastasis from sigmoid colon cancer. Therefore, we diagnosed metachronous liver metastasis from sigmoid colon cancer occurring 15 years after surgery. Metachronous liver metastasis occurring more than 10 years postoperatively is rare, with only 8 reported cases including our own in Japan.