**9. Surveillance**

Aim of surveillance after curative resection of primary colorectal cancer is to identify asymptomatic recurrences who may be a potential candidate for curative resection. Although most randomized trials suggest modest survival benefit, not all trials are consistent. The benefit Intensive versus less intensive follow up strategies is still debated. Accordingly, surveillance strategies vary among different expert groups. Multiple meta-analyses have been conducted in an attempt to rationalize the surveillance plan, the latest being Cochrane analysis 2019, which examined the data from 13,216 patients from 19 randomized trials and found there was no

overall survival benefit from intensive surveillance. Intensive follow up resulted in higher rates of salvage surgeries with curative intent; however, this did not result in improved survival. Furthermore, these results were confounded by heterogeneity of the trials included in the meta-analyses. For example, definition of intensive versus less intensive follow up varied among the trials in terms of frequency of follow up [78]. In addition some trials included patents with stage I disease who have low rates of recurrence. Despite inconsistencies in the data, and the fact that curative metastasectomy improves survival in colorectal cancer patients, intensity of follow up should be tailored according to patient and cancer characteristics. Surveillance modalities include physical examination, carcino-embryonic antigen (CEA) and computerized tomography (CT) for surveillance. Follow up guidelines varies between the expert groups [79, 80]. A relatively intense follow up is reasonable for the first 3 years after the curative surgery, with 3–6 monthly physical examination and measurement of CEA. A 12 monthly CT scan is appropriate for the first 3 years and CT scans should be performed on any clinical suspicion thereafter. A colonoscopy is indicated after adjuvant therapy, if a complete colonoscopy was not performed at the time of surgery. Otherwise a routine colonoscopy should be performed at 12 months and then 5-yearly unless an adenomatous polyp is found which should prompt an earlier follow up colonoscopy.
