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Incidence of Colorectal Cancer Increasing in Young Adults
The incidence of colorectal cancer (CRC) among young adults (20 to 39 years of age) has increased during the past 20 to 30 years despite declining rates of CRC for the U.S. population overall, according to findings published in the Journal of Adolescent and Young Adult Oncology.
Researchers at the University of California, Irvine, analyzed 231,544 cases from 1988–2009 (including 5,617 young adults) from the California Cancer Registry. They assessed age-specific incidence rates of CRC by race/ethnicity, gender, and colorectal tumor location, and calculated the biannual percent change (BAPC) to monitor the change in incidence over the 22-year study period.
The study population was predominantly Caucasian (71%), but also included Hispanics (12%), Asian/Pacific Islanders (10%), and African Americans (7%). The mean age of all study participants at diagnosis was 69 years.
CRC is uncommon in people younger than 50 years of age. Among older adults, screening to detect and remove precancerous polyps has largely contributed to declining CRC rates for the U.S. population as a whole.
In the new study, however, the authors found significant increases in CRC incidence among the 20–29 year and 30–39 year age groups. The data also showed a greater CRC risk for certain racial groups, and differences in tumor location and stage at diagnosis, for young adults compared with individuals 50 years of age and older.
Despite a low CRC incidence, both male and female young adults (aged 20 to 29 years and 30 to 39 years) had a significantly increased BAPC in the incidence of CRC.
The absolute incidence of CRC among adults aged 20 to 29 years ranged from 0.7 (African-American females and Hispanic females) to 1.2 (Asian/Pacific Islander males) per 100,000. Among young adults aged 30 to 39 years, the absolute incidence of CRC ranged from 3.4 (Hispanic females) to 5.0 (Asian/Pacific Islander males) per 100,000.
CRC incidence rates varied widely by tumor subsite, race/ethnicity, and age. Of note, the greatest observed biannual percentage changes were for distal colon cancer among Hispanic females aged 20to 29 years (BAPC: +15.9%; P = 0.042) and Hispanic males aged 30 to 39 years (BAPC: +10.4%, P < 0.001). Large BAPC increases were also observed among Hispanic females aged 20 to 29 years for rectal cancer (+10.5%) and among Caucasian males aged 20 to 29 years for rectal cancer (+9.4%).
The authors concluded that the incidence of CRC among young adults is low in terms of absolute incidence, but is increasing over time. They also found that CRC in young adults (a largely unscreened population) was more likely to be diagnosed at an advanced stage and therefore less likely to be cured.
Sources: Mary Ann Liebert, Inc.; January 23, 2015; and JAYAO; December 15, 2014.