Introduction Colonoscopic surveillance after colorectal cancer resection is widely practised despite little evidence that it improves survival. The optimum protocol for colonoscopic follow-up after colorectal cancer resection has not yet been elucidated. We audited the outcome of an empirical colonoscopic follow-up programme in a cohort of patients who underwent colorectal resection with a minimum of five years follow-up to establish patterns of metachronous neoplasia and suitable surveillance intervals.
Methods The colonoscopic records, biopsy results and follow-up details of patients diagnosed with colorectal cancer between June1990 and June1996 were reviewed. The number and type of metachronous neoplastic lesions diagnosed was recorded. Rates of development of new neoplasms were estimated by calculating the time from operation to their first discovery. Factors predictive of further development of polyps or cancer were sought. Results were compared to published reports of intensive follow-up programmes.
Results Seven hundred and ninety-eight patients underwent colorectal resection with curative intent during the study period. 226 patients had one or more follow-up colonoscopies (mean time post resection 48.8 months). In total 352 colonoscopies, encompassing 1437 patient years of surveillance, were performed. Nine metachronous cancers in eight patients, five of which were asymptomatic were diagnosed by colonoscopy at a mean of 63 months. Three asymptomatic recurrences were diagnosed but all were inoperable. 70 (31%) patients had adenomatous polyps diagnosed after a mean time from operation of 34 months for simple adenomatous polyps and 21 months for those with advanced features. Patients with multiple polyps or advanced polyps at the initial colonoscopy were more likely to form subsequent polyps. Only 5.8% of patients with a single adenoma or a normal colon formed an advanced adenoma over the next 36 months of surveillance.
Conclusion The results of an empirical colonoscopic follow-up programme compared favourably to the results of the intensive programmes reported in the literature. Most patients are at very low risk of developing significant colonic pathology over the first five years after resection. Colonoscopic surveillance intervals need not be less than five years unless the patient has multiple adenomas or advanced adenomas at the first colonoscopy. Three yearly surveillance intervals are most probably adequate in these individuals.