New estimates of the lifetime risk of developing colorectal cancer published in the Journal of Medical Screening, a BMJ publication, suggest that screening should start at age 50 or 55 in the general population.
For individuals with a family history of colorectal cancer, screening is recommended from age 40-44.
Using cancer registry data, researchers in France estimated the lifetime risk of colorectal cancer among the general population and among first degree relatives of patients with sporadic colorectal cancer or pre-cancerous lesions, over a five-year period.
They found that one in 23 men and one in 40 women will develop a colorectal cancer during their lifetime. This risk rapidly increased with age and degree of family history of colorectal cancer. At age 74, the risk varied between 8% (with one family member affected) and 26% (with two affected) in men and 4% and 14% respectively in women.
These findings, alongside results from previous studies, suggest that screening in the general population should start at 50 or 55, say the authors.
For relatives of patients with a colorectal cancer before the age of 45, or for those with at least two affected family members, the lifetime risk is high enough (over 10%) to recommend screening after age 40, they conclude.
(Reference: Family history and risk of colorectal cancer: implications for screening programmes, Journal Of Medical Screening 2000; 7: 136-140.)