Scientists Say Colorectal Cancer Cases Are Rising—Here’s What to Do to Stay Safe

Meet the experts: Andreana Holowatyj, Ph.D., young adult cancer researcher and assistant professor of hematology and oncology at Vanderbilt University Medical Center and Vanderbilt-Ingram Cancer Center; Michael Hall, M.D., director of Gastrointestinal Risk Assessment at Fox Chase Cancer Center; Heather M. Ochs-Balcom, Ph.D., associate professor in the Department of Epidemiology and Environmental Health at the University at Buffalo

Colorectal cancer is the third most common cancer in both men and women in the U.S. and the second leading cause of cancer-related death, according to the report. In adults under 50, colorectal cancer is the leading cause of cancer death. Unfortunately, three in four colorectal cancers diagnosed in adults under the age of 50 are advanced stage at diagnosis.

“It’s alarming to see this shift toward younger populations being diagnosed with colorectal cancer that historically has been an older person’s disease,” says Andreana Holowatyj, Ph.D., young adult cancer researcher and assistant professor of hematology and oncology at Vanderbilt University Medical Center and Vanderbilt-Ingram Cancer Center.

Rectal cancer doesn’t get that much attention from the general public in the colorectal cancer sphere. In fact, this disease is often referred to as “colon cancer,” leaving out rectal cancer altogether. But what is rectal cancer, why is it fueling an increase in cases in younger people, and what are the signs to look out for? Doctors explain.

What is rectal cancer?

Rectal cancer is a type of cancer that develops in the tissues of the rectum, the last six inches of the large intestine, Holowatyj says. “The majority of rectal cancers are adenocarcinomas that arise from the cells that line the inner side of rectum—the side that faces our biological waste/stool,” says Michael Hall, M.D., director of Gastrointestinal Risk Assessment at Fox Chase Cancer Center.

The risk factors of colon and rectum cancers are the same. These are the biggest risks of developing this type of cancer, according to the National Cancer Institute (NCI):

• Having a first-degree relative with a history of colon or rectal cancer
• Having a personal history of high-risk colorectal polyps
• Having certain inherited genes
• Having a personal history of chronic ulcerative colitis or Crohn’s disease for eight years or more
• Drinking three or more alcoholic beverages a day
• Smoking

• Your race

• Having obesity

Why is rectal cancer fueling colorectal cancer cases in younger adults?

It’s not clear at this point. “That’s the million-dollar question, and one that work from my team, as well as many other colleagues across the country and world, are working to understand,” Holowatyj says. She suggests there may be a “constellation of factors” that’s fueling this rise in cases.

Holowatyj points to data that suggests people born in 1990 are twice as likely as those born in 1950 to develop colon cancer—and four times as likely to be diagnosed with rectal cancer. As a result, she and other researchers are trying to investigate what exposures have changed for people since the 1950s that may be fueling this. “The main question is: How are these exposures uniquely impacting the cells in the rectum to become cancerous?” she says.

A higher consumption of processed foods and sugars, and gut microbiome changes may be fueling this growth as well, Dr. Hall says.

Obesity may play a role, too, according to Heather M. Ochs-Balcom, Ph.D., associate professor in the Department of Epidemiology and Environmental Health at University at Buffalo. “Colorectal cancer is one of the well-recognized obesity-related cancers, and recent evidence supports the links specifically of abdominal obesity,” she says. “We need more large epidemiologic studies on dietary factors, alcohol intake, physical activity, and comorbidities to study how they are related to the rising incidence of early-onset colorectal cancer.”

Holowatyj also says many suggest that something in the environment may be fueling inflammation in the body that then raises the risk of cancer. But Holowatyj says the reason for the increase in cases in younger people is likely more complex. “It may not all be driven by one particular factor,” she says. “It may be a combination of things we don’t know about yet and things we do know about.”

Holowatyj stresses that researchers are trying to solve this mystery.

Symptoms of rectal cancer

Symptoms of rectal cancer tend to overlap with those of colon cancer, according to the American Cancer Society (ACS). Those include:

• A change in bowel habits that lasts for more than a few days. This may include diarrhea, constipation, or narrowing of the stool.

• Feeling like you need to have a bowel movement after already having one.
• Rectal bleeding with bright red blood.

• Blood in the stool, which may look dark brown or black.

• Cramping or stomach pain.
• Weakness and fatigue.
• Weight loss without a clear cause.

Blood in stool may be hard to spot at first, according to the ACS. However, over time, blood loss may accumulate and lead to low red blood cell counts or anemia. (Anemia can be one of the first signs of colorectal cancer, per the ACS.)

How to lower the risk of rectal cancer

Some risk factors of rectal cancer, like your genes, can’t be avoided. But the ACS offers several suggestions for lowering your risk of the disease:

• Try to maintain a healthy weight.
• Stay physically active.
• Eat plenty of vegetables, fruits, and whole grains, while minimizing red and processed meats.
• Avoid or limit alcohol.

• Don’t smoke.

What to do if you develop symptoms of colorectal cancer

It’s easy to brush off symptoms of colorectal cancer as a newer food intolerance or other less severe health issue, but Holowatyj stresses the importance of getting things checked out. “The most important thing is to seek out a healthcare provider for appropriate testing,” she says.

Holowatyj notes that nearly half of patients who are eventually diagnosed with colorectal cancer reported having blood in their stool, while 40% had abdominal pain. Still, it may take up to six months for some younger patients to get a proper diagnosis, she says. “It’s important to seek timely medical attention and advocate for testing to work up these symptoms,” she says. “That’s absolutely crucial.” Dr. Hall agrees. “Don’t blow off symptoms,” he says.