Insufficient evidence regarding the optimal screening strategy for this population means that a number of published screening recommendations exist differing in the definition of risk, type and frequency of tests recommended, and the age at which individuals should start screening.
For people in this category, their risk of colorectal cancer (CRC) is as high at age 35 years as that of the average population at age 50 years, which is about 1%. This would justify biennial screening with iFOBT from age 35 to 44 years. By age 45 years, their risk is above 4%, which is sufficiently high to warrant colonoscopy every 5 years from 45 to 74 years.r There have been no studies conducted to determine the utility of beginning screening 10 years before the earliest diagnosis in the family, which was a recommendation in previous guidelines.r
There have been no trials of CRC prevention for this risk category. Considerable evidence supports the effectiveness of aspirin as risk-reducing medication for CRC in patients with Lynch syndrome.r
Randomised controlled trials were reviewed by Cancer Council Australia and this led to the guarded conclusion that aspirin is effective in the primary prevention of CRC. After taking into account the observational epidemiological data and other potential benefits, the revised guidelines have made a strong recommendation to consider universal aspirin chemoprevention except where contraindicated, especially for those with excess cardiovascular risk.r Thus it has been included in these guidelines for those at high risk.
Modifiable lifestyle risk factors for colorectal cancer
For a summary of the evidence for modifiable lifestyle risk factors for CRC, see Cancer Council Australia: Colorectal Cancer Guidelines Working Party. Clinical practice guidelines for the prevention, early detection and management of colorectal cancer. These recommendations apply to the general population; there is no specific evidence for the high-risk group.