Interventions/family history of CRC
There are no controlled comparisons of screening in people with a mild or modest family history of CRC. Most experts, if they accept that average-risk people should be screened starting at age 50 years, suggest that screening should begin earlier in life (e.g., at age 35 to 40 years) when the magnitude of risk is comparable to that of a 50-year-old. Because the risk increases with the extent of family history, there is room for clinical judgment in favor of even earlier screening, depending on the details of the family history. Some experts suggest shortening the frequency of the screening interval to every 5 years, rather than every 10 years.
A common but unproven clinical practice is to initiate CRC screening 10 years before the age of the youngest CRC case in the family. There is neither direct evidence nor a strong rational argument for using aggressive screening methods simply because of a modest family history of CRC.
These issues were weighed by a panel of experts convened by the American Gastroenterological Association before publishing clinical guidelines for CRC screening, including those for persons with a positive family history of CRC. These guidelines have been endorsed by a number of other organizations.
The American Cancer Society and the United States Multi-Society Task Force on Colorectal Cancer have published guidelines for average-risk individuals.[128,349] The recommendations for screening average-risk persons (asymptomatic, older than 50 years, with no other risk factors) include the following options:
- Fecal occult blood screening each year (Level of evidence: 1) and/or screening flexible sigmoidoscopy every 5 years (Level of evidence: 2), followed by colonoscopy if adenomatous polyps or blood in the stool is found;
- Double contrast barium enema every 5 to 10 years (Level of evidence: 5); or
- Colonoscopy every 10 years (Level of evidence: 3).
Individuals with a first-degree relative diagnosed before age 60 years with CRC or adenoma should be offered full-colon screening beginning at age 60 years or 10 years prior to the earliest diagnosis in the family (Level of evidence: 5).
Rare Colon Cancer Syndromes
Peutz-Jeghers syndrome (PJS)
PJS is an early-onset autosomal dominant disorder characterized by melanocytic macules on the lips, and the perioral and buccal regions, and multiple gastrointestinal polyps, both hamartomatous and adenomatous.[350,351,352] Germline mutations in the STK11 gene at chromosome 19p13.3 have been identified in the vast majority of PJS families.[353,354,355,356,357] (Refer to the Peutz-Jeghers Gene(s) section in the Colon Cancer Genes section of this summary for more information.) The most common cancers in PJS are gastrointestinal. However, other organs are at increased risk of developing malignancy. A systematic review found a lifetime cumulative cancer risk, all sites combined, of up to 93%.Table 10 shows the cumulative risk of these tumors. The high cumulative risk of cancers in PJS has led to various screening recommendations summarized in Table 11.