A Case of Spontaneous Regression of Advanced Transverse Colon Cancer

Abstract

An 87-year-old woman underwent total colonoscopy following a positive fecal occult blood test. A type 2 tumor occupying two-thirds of the circumference was detected in the transverse colon close to the splenic flexure. The biopsy revealed a poorly differentiated adenocarcinoma. As computed tomography scans showed wall thickness and irregular serosa, the depth of the tumor was predicted to be T3 or deeper. The patient underwent an open partial transverse colectomy. The resected specimen showed only an ulcer at the tumor site. Histopathology revealed inflammatory cell infiltration and fibrosis at the ulcer site ; cancerous tissue was not found. A month and a half after surgery, total colonoscopy was performed ; this revealed an absence of tumor. There has been no evidence of recurrence for 4 years and 6 months. As CD8+ T cells aggregated around the tumor in the biopsy specimen, tumor immunity may have been associated with the spontaneous regression.