A new study by the American Cancer Society found that, although its incidence among older adults has been decreasing recently, colon cancer is increasing among young adults.

In the 1980s to the early 2000s, the average age of colon cancer patient was 72.  That age has now dropped to 66.  The largest reason for the decrease in average age has been the number of new cases among those under the age of 50.

The reasons for this shift are not clear.  About half the cases of colon cancer is based on genetic factors.  But the other half can be attributed to other risk factors:  smoking, an unhealthy diet, excess weight, physical inactivity, and high alcohol consumption.  Since these are modifiable risk factors, a possible reason the rising incidence of colon cancer can be found in an increases in these factors. Also, the increased incidence amount young people has occurred within a relatively short time frame, further pointing to environmental factors.    

Younger adults are also more likely to be diagnosed with advanced colorectal cancer. The report found that 26 percent of people aged 50 and younger have advanced disease when they are diagnosed, compared to 19 percent of people age 65 and older.

Some of the reasons may relate to screening.  For people aged 65 and older, the incidence of colorectal cancer fell rapidly during the 2000s, perhaps because of more widespread early detection and screening. Hopefully adjusting the recommended age for screening colonoscopy will have the same affect.

To counter the increasing rate of colon cancer in younger adults, one emphasis is on changes in screening.  In the past, most health groups had recommended that screening colonoscopies start at age 50.  The American Cancer Society is now reducing that age to 45. 

Read the American Cancer Society’s Colorectal Cancer Screening Guidelines