A case of spontaneous regression of colon cancer is reported. The patient, an 80-year-old man, was referred to hospital in January 2004. Colonoscopy revealed a type 2 tumour in the transverse colon which was diagnosed as an adenocarcinoma. A computed tomography scan also revealed a right renal tumour. Urological examination disclosed renal cell cancer. The patient subsequently refused surgical treatment and did not visit the hospital again for 6 months, during which time he received neither anticancer treatment nor any other medication. Another colonoscopy in August 2004 resulted in reclassification of the tumour to a IIc lesion, and the biopsy was negative for cancer. A right nephrectomy was carried out, and observation was performed for development of colonic lesions. In January 2007, colonoscopy revealed that the IIc lesion had disappeared. The patient was still alive with no sign of recurrence 64 months after disappearance of the lesion.
Conclusion: This finding suggests that spontaneous regression can occur in advanced colon cancer.