Colon cancer red flags to look out for if you're younger than 50, according to researchers

• Researchers identified 4 symptoms that people diagnosed with colon cancer under 50 are most likely to experience.
• Colon cancer rates are on the rise among young people, and scientists still don't know why.

Young people diagnosed with colon cancer are more likely to experience four distinct symptoms, including rectal bleeding and diarrhea, according to a new study.

Colon cancer patients under the age of 50 are more likely to have had experienced four symptoms — abdominal pain, rectal bleeding, diarrhea, and iron deficiency — in the three month to two-year period before getting diagnosed, according to research published May 4 in the Journal of the National Cancer Institute.

Researchers at the Washington University School of Medicine in St. Louis analyzed health insurance data of more than 5,000 patients diagnosed with cancer before 50. They found having a single one of those four symptoms nearly doubled the risk for colon cancer.

Having two symptoms increased the risk for colon cancer by 3.5 times, and having three or four led to a 6.5-time increase.

The findings could be critical in helping young people identify warning signs. Colon cancer among young people is on the rise, as recent data from the American Cancer Society found the proportion of colorectal cancer in people under 55 doubled between 1995 to 2019, from 11% to 20%.

Young people aren't typically diagnosed until the cancer has reached an advanced stage. One 2019 study found that, among people diagnosed with colon cancer, more than half of people under 50 receive a diagnosis at stage three or four, compared to just 40% of people over 50 diagnosed at those later stages.

Catching colon cancer early is key to preventing death: the five-year relative survival rate is about 90% if the cancer doesn't spread to other parts of the body. But the symptoms of colon cancer, like fatigue and weight loss, can be confused for GI problems, and many doctors don't screen young people for colon cancer.

"To date, many early-onset colorectal cancers are detected in emergency rooms, and there often are significant diagnostic delays with this cancer," senior investigator Yin Cao said in a release.

Don't wait to get screened for colon cancer, doctors say

Scientists are still studying why colon cancer rates are rising in young people, but they suspect lifestyle factors could be behind the trend.

Diets low in fiber and high in processed meat have been linked to an increased risk of the disease, and some experts hypothesized the recent popularity of meat-heavy diets like keto and paleo is partly to blame for rising cancer rates.

Obesity, which is also on the rise among young people, can increase the risk for colon cancer. The chronic disease can also increase the risk for heart disease, yet another illness inflicting young people at higher rates than in the past.

The Centers for Disease Control and Prevention recommend everyone start getting screened for colon cancer at 45, and people with a family history talk to their doctor about the disease sooner rather than later.

"It is very clear that signs and symptoms that might indicate colorectal cancer in those under 50, and particularly rectal bleeding, should be evaluated by a healthcare professional promptly and not dismissed as 'only hemorrhoids' or 'normal,'" Dr. David Greenwald, a professor of medicine and gastroenterology at the Icahn School of Medicine at Mount Sinai, previously told Insider.