Development of metachronous neoplasms after colorectal cancer resection: absence of synchronous neoplasms predicts a lower risk

Aim The appropriate interval for performing surveillance colonoscopy following curative resection for colorectal cancer is unclear. The high demand for colonoscopy in New Zealand's public health system requires careful prioritisation according to clinical urgency. The aim of the study was to identify a group of patients at lower risk for the development of metachronous neoplasms (cancer or adenoma) for which a less intensive surveillance programme may be appropriate. Methods Review of patients presenting to Wellington Hospital, New Zealand for surveillance colonoscopy following curative resection for colorectal cancer and having had no prior history of a colorectal neoplasm. Results One-hundred patients underwent 149 surveillance colonoscopies. Forty-six had a synchronous neoplasm at the time of colorectal cancer resection and they were 2.5 times more likely to have developed a metachronous neoplasm at both 3 (p=0.008) and 5 (p=0.001) years than those who did not have a synchronous neoplasm. No metachronous cancers developed in those without a synchronous neoplasm. Conclusion Patients who undergo curative resection of a colorectal cancer and have no synchronous neoplasms are at lower risk of developing metachronous neoplasms. A less intensive colonoscopic surveillance programme may be more appropriate.