Natural history and long-term outcomes of patients treated for early stage colorectal cancer.

Background: The long-term natural history of early stage colon cancer and the outcome of long-term colonoscopic surveillance in routine specialist clinical practice after removal of the incident cancers have not been fully defined. In the present long-term evaluation up to 25 years, metachronous neoplasia, including both advanced adenomas and carcinomas, was defined.

Methods: All early stage colorectal cancer patients evaluated consecutively from a single clinical practice underwent follow-up colonoscopic evaluations after removal of the incident cancer and clearing of neoplastic disease. Colonoscopic surveillance was planned for two phases - initially on an annual basis for five years, followed by continued surveillance every three years up to 25 years with removal of any metachronous neoplastic lesion.

Results: A total of 128 patients (66 men and 62 women) with 129 incident early stage colorectal cancers were evaluated. Virtually all patients were symptomatic, usually with clinical evidence of blood loss. Incident early cancers were located throughout the colon, especially in the rectosigmoid, and showed no pathological evidence of nodal or other metastases. All patients evaluated during the first five years did not experience recurrent disease or have metachronous cancer detected. After five years, a total of 94 patients were evaluated up to 25 years; six of these patients were found to have seven metachronous colon cancers. All developed cancer more than seven years after removal of the incident colorectal cancer, including six asymptomatic adenocarcinomas, of which only one had evidence of single node involvement. Another patient in this cohort developed a poorly differentiated neuroendocrine carcinoma of the colon. In addition, 45% of patients had a total of 217 adenomas removed, including 11% of patients with 33 advanced adenomas. Among 14 patients with advanced adenomas, seven (50%) developed ≥1 late metachronous cancers.

Conclusions: Following removal of an incident symptomatic early stage colorectal cancer, the risk of later metachronous neoplasia persists for an extended period more than five years after removal of the incident colorectal cancer. Moreover, risk for late metachronous cancer appears to be predicted by the presence of multiple adenomas or advanced adenomas; most metachronous cancers in this cohort were detected using colonoscopy before onset of symptoms and at an early stage.