The researchers theorize that these increases may be related to rising rates of obesity and changes in dietary patterns, including increased consumption of fast food.
Overall incidence rates for colorectal cancer in the United States have been on the decline since the mid-1980s, with the drop accelerating in the most recent time period. Rates are now dropping 2.8 percent per year in men and 2.2 percent per year in women, largely due to an increase in screening, particularly colonoscopy, among individuals ages 50 years and older. Screening can reduce colorectal cancer incidence by detecting and removing polyps before they become cancerous.
But recent incidence trends among adults younger than 50 years, for whom routine screening is not recommended, have not been analyzed thoroughly.
In a new analysis, American Cancer Society researchers led by Rebecca L. Siegel, looked at trends in colorectal cancer incidence rates between 1992 and 2005 among young adults (ages 20 to 49) by sex, race/ethnicity, age, stage at diagnosis, and anatomic subsite. The study found that among individuals ages 20 to 49, incidence rates of colorectal cancer increased 1.5 percent per year in men and 1.6 percent per year in women from 1992 to 2005.
The researchers address several possibilities for the rise, including rising rates of obesity, which is a major risk factor for colorectal cancer.
MEDICA.de; Source: American Cancer Society