Genetic counseling and testing is also available for those at risk of FAP. Their lifetime risk of
developing colorectal cancer is near 100%, and in most cases it develops before the age of
40. People who test positive for the gene change linked to FAP should start colonoscopy
during their teens (see the section “Can colorectal polyps and cancer be found early?”). Most
doctors recommend they have their colon removed when they are in their 20s to prevent
cancer from developing.