Colorectal cancer — cancer that originates in the colon or the rectum — has long been thought to affect older populations of people. The Centers for Disease Control and Prevention currently recommend that adults over age 50 have regular preventative colorectal cancer screenings. However, new data is showing that across the United States and Canada, rates of colorectal cancer are rising among people in their 20s and 30s, The New York Times reports.
The new data, published in 2019 in the journal JAMA Network Open, examined colorectal cancer data compiled in the National Cancer Incidence Reporting System and the Canadian Cancer Registry. It concluded that in younger men, there was an annual percentage increase in colorectal cancer diagnosis of 3.46% from 2006 to 2015; among younger women, there was an annual percentage increase of 4.45% between 2010 and 2015. The study noted that young adult-onset colorectal cancer is typically linked to a family history of colorectal cancer or Lynch syndrome, which is inherited and associated with a genetic predisposition for several cancers.
The American Cancer Society has responded by lowering the recommending colorectal cancer screening age to 45, but their website is careful to note that this recommendation only applies to people with “average risk” levels. People without the following experiences are considered by the American Cancer Society to be at “average risk” of colorectal cancer:
- A personal history of colorectal cancer or certain types of polyps
- A family history of colorectal cancer
- A personal history of inflammatory bowel disease (ulcerative colitis or Crohn’s disease)
- A confirmed or suspected hereditary colorectal cancer syndrome, such as familial adenomatous polyposis (FAP) or Lynch syndrome (hereditary non-polyposis colon cancer or HNPCC)
- A personal history of getting radiation to the abdomen (belly) or pelvic area to treat a prior cancer
Without these specific risk factors, then, younger people may not know to get screened earlier for colorectal cancer. With the increase in colorectal cancer rates among younger populations, however, studies are seeking additional risk factors that account for the rising rates of diagnosis. To that end, a 2017 study published in the journal Oncotarget suggests that individuals with Type-2 diabetes are at a greater risk of colorectal cancer.
A major component of the connection between Type-2 diabetes and colorectal cancer is the body’s inflammatory response. Many of the same signaling pathways that control the body’s inflammatory response with Type-2 diabetes are also linked to higher rates of colorectal cancer.
This relationship between inflammation and colorectal cancer is not limited to individuals with Type-2 diabetes, however. A 2011 study published in the journal Gastroenterology found that people with ulcerative colitis and Crohn's disease are at increased risk of developing colorectal cancer. Both ulcerative colitis and Crohn’s disease, as described on the American Cancer Society’s webpage discussing colorectal cancer risks, are inflammatory bowel diseases. However, a 2014 study published in the World Journal of Gastroenterology suggests that these inflammatory-response signaling pathways can be targeted by specific therapeutic strategies to reduce inflammation and subsequent colorectal cancer risk.
The role of Type-2 diabetes and inflammatory bowel disease in the increased colorectal cancer risks among people in their 20s and 30s is especially important, given the disparities in healthcare accessibility and treatment for both conditions. According to a 2013 study published in the journal Inflammatory Bowel Diseases, racial and socioeconomic statuses are huge predictors of healthcare delivery and effectiveness for people with an inflammatory bowel disease. These disparities are also present in the diagnosis and treatment of people with Type-2 diabetes, according to a 2017 study published in the journal Clinical Diabetes. Both studies reviewed years’ worth of peer-reviewed literature about the conditions to draw their conclusions.
Especially for racially and economically marginalized individuals, then, it is important to recognize the signs and symptoms of colorectal cancer. According to the American Cancer Society’s website, these warning signs of colorectal cancer include:
- A change in bowel habits, such as diarrhea, constipation, or narrowing of the stool, that lasts for more than a few days
- A feeling that you need to have a bowel movement that's not relieved by having one
- Rectal bleeding with bright red blood
- Blood in the stool, which may make the stool look dark
- Cramping or abdominal (belly) pain
- Weakness and fatigue
- Unintended weight loss
Recognizing these signs can lead to increased preventative screening among the young people who need it, which is extremely significant. Because the same JAMA Network Open study that found an increased rate in colorectal cancer in younger people also noted a decrease in colorectal cancer rates among people over age 50. According to the study, this decrease can be attributed to heightened awareness and preventative screening among older individuals. This conclusion offers hope that with similar heightened awareness and screening, younger individuals can also see declining rates in colorectal cancer.