New data from Canada and the U.S. is showing a substantial increase in colorectal cancers among adults in their 20s and 30s. Younger patients were also likely to have advanced cases more often than older patients. The results of this study have been published in the journal JAMA Network Open.
The researchers looked at the data for all Canadians diagnosed with colorectal cancer between 1969 and 2015. The study found that from 2010 to 2015, colorectal cancer rates increased by 4.45 percent among women under age 50. Between 2006 and 2015, rates increased by 3.47 percent among Canadian men under age 50. The risk of colorectal cancer in the youngest group of men (those aged 20 to 29 in 2015) was more than double that age group’s risk in 1936.
The authors of the new study, led by Dr. Darren Brenner of the University of Calgary, expressed concern about the worrisome trend. Dr. Brenner, a molecular cancer epidemiologist at the university, said, “We thought that this trend would slow down or level off after people first noticed it a few years ago. But every year we keep seeing the increase in colorectal cancer among young people, and it is very alarming.”
Researchers in the United States have observed a similar pattern. Scientists at the University of Texas at Austin found that the number of newly diagnosed colorectal patients under age 50 rose from 10 percent in 2004 to 12.2 percent in 2015. An international study published online in May showed the trend may be worldwide. Published in The Lancet, the study looked at colorectal cancer rates among 143 million people in several high-income countries, including Australia, Canada, Denmark, Norway, New Zealand, Ireland, and the U.K. and found rates have risen dramatically among those under the age of 50 over the past 10 years.
The research has prompted changes in screening guidelines for the cancers. The American Cancer Society now recommends screening average-risk individuals for colorectal cancer starting at age 45. The Canadian Preventative Task Force on Preventative Health Care still recommends screening every two years for those between 50 and 74, but are debating making changes that would lower the recommended starting age.