Colorectal cancer (CRC) is among the leading causes of cancer deaths worldwide, and studies have shown that screening with fecal occult blood alone can reduce mortality by about 15%, and screening with colonoscopy can reduce mortality by about 50%. Approximately 10-15% of patients with CRC have a family history of CRC but no CRC-related genetic syndromes such as Lynch syndrome or familial adenomatous polyposis. The relative risk of CRC in these patients is two to six times higher than in the general population, depending on the age of their first-degree relative at the time of CRC and the number of CRC cases in the family. Experts recommend screening colonoscopy for these patients, but there is no clear statement on the optimal interval of years. Current guidelines recommend colonoscopy at intervals ranging from 3 to 5 years and up to 6 years from age 45. A randomized controlled study on this issue was conducted by Professor Hennink and others at Leiden University Medical Center in the Netherlands and published in the Journal of Clinical Oncology in December 2015. Inclusion criteria were 1 first-degree relative < 50 years of age at the time of CRC or 2 relatives 45-65 years of age at the time of CRC. At enrollment, those with 0 to 2 adenomas were randomized into two groups: group A had colonoscopy at year 6, and group B had colonoscopy at years 1 and 6. The primary observation was progressive adenomatous polyps (AAPs), and the risk factors studied included sex, age, type of family history, and colonoscopy findings at enrollment. A total of 528 subjects were included, 262 in group A and 266 in group B. Intentional treatment analysis showed no statistical difference in the proportion of patients with AAPs at year 6 in group A compared with follow-up monitoring at year 3 in group B (6.9% in group A and 3.5% in group B), and no statistical difference in the proportion of patients with AAPs at year 6 in group A compared with follow-up monitoring at year 6 in group B (3.4% in group B). The presence of AAPs only at enrollment was significant in predicting the presence of AAPs at the first follow-up. After correcting for the difference in AAPs at entry, the proportion of AAPs between the two groups was statistically significantly different at the first follow-up and final monitoring. Given the relatively low incidence of AAPs at 6 years in Group A and the absence of CRC, the authors concluded that a 6-year monitoring interval was appropriate. For those with AAPs and ≥3 adenomas, a monitoring interval of 3 years may be considered.