Natural history of sigmoid colon cancer: Report of a patient observed for 4 years

We report a case of sigmoid colon cancer that was left untreated for a peri od of 4 years, because the patient declined treatment. A 59-year-old man wa s found to have an early carcinoma of the sigmoid colon measuring approxima tely 12 mm in diameter. The lesion, initially a flat cancer, increased in h eight and became sessile 4 months later. Subsequently, the central portion of the lesion became ulcerated, leaving an elevated ring along its peripher y. The lesion eventually evolved into an ulcerated, invasive cancer. This s equence has not been observed with colonoscopy before.