Excluding skin cancer, colorectal cancer (CRC) is the third most common cancer diagnosed in men and women in the United States. Since the mid-1980s there has been a gradual decline in the incidence of CRC in both men and women over age 50 with the greatest decline seen in those over age 65. Since the mid-2000s the decline in the less than 65 age group has been approximately 3% per year. This decline has been attributed largely to the CRC cancer screening programs with early detection and the removal of pre-cancerous polyps.
Colorectal Cancer Trends
While those greater than age 50 have seen a significant decline in CRC incidence, since 2000 those under age 50 have seen an increased incidence of CRC and from 2009 to present this increase is approximately 1.6% per year. Notably, the increase in the younger patients followed a decade of decline in this group from the late 1970s into the early 1980s. Those under the age of 50 now account for approximately 11% of new CRC diagnoses. It is unknown what is accounting for this increase. Of the more commonly quoted risk factors from family history to inherited genetic disorders, excess alcohol consumption, diet, obesity etc. as being associated with CRC, one can point possibly to increased obesity as a cause but this clearly cannot account for the overall increase in patients less than 50 years old. The Chief Cancer Control Officer of the ACS stated: “we have to face reality…..we do not know why it is increasing.”
In light of the increased incidence of CRC in patients under age 50, The American Cancer Society has recently changed its advice on screening for CRC and recommends that it begin at age 45. Because of the unknown etiological factors, not all are in agreement with this recommendation and other groups including the US Preventive Services Task Force have maintained the recommendation for screening to start at age 50. Some are troubled with unknowns surrounding the increase incidence in the younger age group and argue that without knowing the cause, the screening may have minimal effect. ACS does agree that the benefits of screening a younger age group are theoretical and studies are still needed to determine the usefulness of the new recommendation in practice. However, they point to the screening which has been so effective in older age groups as one modality to be explored as additional studies on etiology are conducted on the under 50-year-old population.
Colorectal Screening Options
Keep in mind that colonoscopy, an invasive procedure with known complications, is but one modality for screening. Fecal immunochemical test (FIT) and high sensitivity guaiac-based fecal occult blood are noninvasive and can be performed annually. Fit- DNA test (Cologuard) is recommended every three years and likewise is a non-invasive procedure. Also, remember the US Preventive Services Task Force states that head-to-head comparison studies have shown that no one screening test is more effective than another in early cancer detection. Will this be true in a younger population with increasing incidence of CRC? Only time and additional etiological studies will tell.