[Brain Metastasis Following Conversion Surgery for Sigmoid Colon Cancer-A Case Report].

A 64-year-old man was diagnosed with KRAS-mutant type sigmoid colon cancer with metastasis in the lung, liver, left adrenal gland, and para-aortic lymph node(T3N1M1b, Stage ⅣB[Union for International Cancer Control 8th edition]). Laparoscopic transverse colostomy was performed to treat colonic obstruction. Subsequently, a combination regimen of capecitabine plus oxaliplatin plus bevacizumab was administered. After 5 courses of chemotherapy, the S8 liver tumor disappeared completely. Sigmoidectomy, para-aortic lymph node dissection, and left adrenal gland resection were performed. After 3 months, right S3 segmental pneumonectomy and right S8 and S10 partial pneumonectomy were performed. R0 resection for the primary lesion and metastatic lesions of the chest and abdomen was achieved. Following the conversion surgery, he was administered the adjuvant chemotherapy regimen of uracil-tegafur plus Leucovorin. After 2 courses of chemotherapy, he presented to our hospital complaining of vomiting and dizziness. Contrast-enhanced magnetic resonance imaging revealed multiple brain metastases. Thus, we should be mindful of the possibility of brain metastasis in cases of unresectable colon cancer showing satisfactory response to chemotherapy with an indication of conversion surgery.