• The “Black Panther” star Chadwick Boseman died on Friday, four years after a stage-three colon-cancer diagnosis. He never spoke publicly about his illness.
  • Boseman was 43 years old. Data suggests that bowel cancers are on the rise among people younger than 50.
  • Studies have found that younger people are more likely to be diagnosed with advanced stages of colorectal cancer.
  • Risk factors include genetics and diet.
  • Visit Insider’s homepage for more stories.

Chadwick Boseman, the actor best known as the star of “Black Panther,” died of complications related to colon cancer on Friday, four years after a stage-three diagnosis. He was 43.

Boseman’s death came as a shock to fans worldwide. He had never publicly spoken about the illness.

In the past three decades, research has consistently found rising rates of colon cancer and related illnesses like rectal cancer among younger people.

People older than 50 are still at a greater risk of developing colon cancer overall. However, people under 50 are more often diagnosed with hard-to-treat, advanced forms of the disease.

One study involving more than 1 million people with colon cancer from 2004 to 2015 found that 51.6% of those under 50 were diagnosed with stage three or four cancer, while 40% of people over 50 were diagnosed at those later stages.

Bowel cancers can be difficult to diagnose because the symptoms - such as abdominal pain, constipation, diarrhea, weight loss, and fatigue - are common with ailments like hemorrhoids, inflammatory bowel disease, or irritable bowel syndrome. What's more, routine testing isn't offered to many people under 50 in several countries, including the US.

If caught early, colon cancer is very treatable, and the five-year relative survival rate is about 90% if the cancer doesn't spread, according to the American Cancer Society.

But it's common for people to have no symptoms until the later stages of the illness. That's why it's important to get screened regularly, especially if you have risk factors.

Obesity, poor diet, and genetics can all increase the risk of bowel cancers

Genetics is a major risk factor for colon cancer. There's evidence that bowel cancers are more likely in younger people with a family history of the disease.

Eating habits also play a role in bowel-cancer risk - diets low in fiber and/or high in red meat and processed meat have been linked to an increased risk of the disease. Some experts have hypothesized that the recent popularity of meat-heavy diets like keto and paleo is partly to blame for rising cancer rates.

Obesity has also been linked to an increased risk of bowel cancer, as have habits like smoking and excessive alcohol use.

The fashion magazine Mr. Porter said in a 2018 profile of Boseman that he was "mostly vegan."

Race and colon cancer

Studies have found that Black people may be disproportionately affected by colon cancer in the US, in part because of racism and barriers to getting medical treatment.

Studies have also found that stress stemming from racism and the hurdles that Black people have historically faced in the US also have tangible effects on health.

Symptoms like rectal bleeding, unexplained weight loss, and constipation or diarrhea can be warning signs of colon cancer

Many symptoms of colon cancer can also indicate more mundane illnesses.

For instance, changes in bowel movements like constipation or diarrhea could indicate colon cancer - but also a plethora of other ailments, including infections, irritable bowel syndrome, or inflammatory bowel disease.

Abdominal pain, unexplained weight loss, and fatigue can also be symptoms of colon cancer.

A major warning sign of colon cancer is rectal bleeding or bloody stool. While this could also be hemorrhoids, you should consult a medical professional if you experience this.

Another unique indicator of colon cancer is the feeling of being unable to empty the bowels, according to the Mayo Clinic.

Colon-cancer treatment

Treatment varies depending on how far the cancer has advanced and where in the bowel it is, but it can include surgery, radiation therapy, chemotherapy, and immunotherapy.

The first-line treatment for colon cancer at stages zero or one is surgery to remove the affected part of the colon.

However, past stage two, when the cancer is still localized but is growing, chemotherapy is considered, particularly if it has perforated the colon and/or appears at risk of resurging after surgery.

Stage three, when the cancer has spread to nearby lymph nodes but not to other organs, requires surgery and chemotherapy, with additional radiation if the cancer is advancing quickly.

At stage four, when the cancer has spread to other organs, patients can undergo a combination of chemotherapy and surgery, radiation therapy, and other targeted treatments to try to treat the cancer or to alleviate the pain associated with it.

Everyone 45 and older should get screened regularly for bowel cancer, and so should younger people at a higher risk

Bowel cancer is diagnosed with a variety of tests, including stool tests, colonoscopies, X-rays, or CT scans of the bowels. A regular physical exam can help identify any abnormalities and detect the cancer sooner.

The American Cancer Society recommends that all adults over 45 be tested regularly for colon cancer, even if they have no symptoms. However, your personal risk factors can determine how frequently you should be tested, so it's best to talk to your doctor about your health history and schedule tests accordingly.

"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.