A Case of Advanced Rectal Cancer in a 17-year-old Woman with High Micro-satellite Instability

Abstract

A case of juvenile rectal cancer that underwent combination chemotherapy and surgery is presented. A 17-year-old woman presented with a 2-month history of abdominal pain and diarrhea. Inflammatory bowel disease was initially suspected, but colonoscopy showed an irregular ulcerative legion suggestive of colon cancer. The biopsy specimen showed mucinous carcinoma with signet ring cells. Computed tomography showed an 8-cm tumor causing bowel obstruction. Laparoscopic colostomy was performed, and small resectable metastatic peritoneal lesions were found. The stage was T4aN2M1c1 Stage IVa. The plan was to give her chemotherapy first and then resect the tumor, because the cancer was in a very advanced stage. Although the tumor became smaller after 3 courses of CAPOX, the serum CEA level was significantly elevated. High anterior resection of the rectum and proximal D3 lymph node dissection were performed with a combination of laparoscopic and open procedures. After the surgery, she was given courses of FOLFIRI and bevacizumab, but peritoneal recurrence was found 4 months later. Since the result for micro-satellite instability was found to be high (MSI-H), she was given pembrolizumab, and she remained stable with the tumor size remaining the same size for 2 years 3 months.