Current colorectal cancer screening guidelines call for testing average risk people when they reach their fiftieth birthday. But is that soon enough? Would earlier screening find more adenomatous polyps and prevent more colorectal cancer?
Scientists at Johns Hopkins School of Medicine reviewed nearly 3,600 autopsies performed at Johns Hopkins Hospital from 1985 through 2004. They compared the younger group from 20 to 49 to older patients from 50 to 89. They looked at the adenomatous polyps found in each decade of life, as well as patient sex and race and the location of the polyps in the colon.
Fewer than 2 percent of the autopsied patients in their twenties had adenomas, rising to about 3.6 percent between ages 40 and 49. However, the number of people with adenomas increased sharply after 50. During the decade between 50 and 59, 10 percent had polyps. By the ninth decade, 12 percent had adenomatous polyps.
In the younger patients, men had a slightly higher risk of polyps than women, and whites about 25 percent more than blacks.
Polyps tended to be on the left side of the colon for both younger and older patient groups, although this difference was stronger for the younger patients. However, African Americans were more likely to have right-sided adenomas, out of the reach of a sigmoidoscopy.
The average number of polyps found in younger people with them was 1. In older adults the number ranged from 1.6 to 1.9. It was unusual for there to be more than two polyps in a young person or five in an individual over 50.
Dr. Francis Giardiello, who directed the study, said,
Our study affirmed that the greatest increase in prevalence was in older adults, abruptly starting in the sixth decade.
Cheryl Pendergrass and her team concluded,
Colorectal adenomas infrequently occur in younger adults and are more prevalent in the left colon. Irrespective of age, blacks have more right-sided adenomas, suggesting the need for screening the entire colorectum. Two or more adenomas in younger adults and 5 or more in older adults represents polyp burden outside the normal expectation.
SOURCE: Pendergrass et al., Clinical Gastroenterology and Hepatology, Volume 6, Number 9, September 2008.
What This Means for Patients
While this study supports the screening guidelines that regular colorectal cancer screening for average risk people should begin at age 50, some people under 50 do have adenomatous polyps and some do get colon and rectal cancer.
Young people with a family history of colorectal cancer or polyps or a personal history of inflammatory bowel disease are at a higher risk for colorectal cancer and may develop it earlier. Check your own personal colorectal cancer risk and discuss the right screening timing — when to begin screening and how often to do it — with your doctor.
People with symptoms of colorectal cancer should always be evaluated with a colonoscopy to rule out cancer at any age.