ACS Study: Finds Colorectal Cancer Rates Have Risen Dramatically in Gen X and Millennials

By David Sampson

A groundbreaking study by American Cancer Society epidemiologist Rebecca Siegel, MPH finds that people born in the United States in 1990 have double the risk of colon cancer and quadruple the risk of rectal cancer compared to those born around 1950, when colorectal cancer risk was lowest.

The study appears in the Journal of the National Cancer Institute, and finds colorectal cancer (CRC) incidence rates are rising in young and middle-aged adults, including people in their early 50s, with rectal cancer rates increasing particularly fast. As a result, three in ten rectal cancer diagnoses are now in patients younger than age 55.

Overall, CRC incidence rates have been declining in the United States since the mid-1980s, with steeper drops in the most recent decade driven by screening. Recently though, studies have reported increasing CRC incidence in adults under 50, for whom screening is not recommended for those at average risk. However, these studies did not examine incidence rates by 5-year age group or year of birth, so the scope of the increasing trend had not been fully assessed.

To get a better understanding, investigators led by Ms. Siegel used “age-period-cohort modeling,” a quantitative tool designed to disentangle factors that influence all ages, such as changes in medical practice, from factors that vary by generation, typically due to changes in behavior. They conducted a retrospective study of all patients 20 years and older diagnosed with invasive CRC from 1974 through 2013 in the nine oldest Surveillance, Epidemiology, and End Results (SEER) program registries. There were 490,305 cases included in the analysis.

The study found that after decreasing since 1974, colon cancer incidence rates increased by 1% to 2% per year from the mid-1980s through 2013 in adults ages 20 to 39. In adults 40 to 54, rates increased by 0.5% to 1% per …read more

Source:: American Cancer Society