Almost immediately after news broke last week that actor Chadwick Boseman had died of colon cancer at age 43, social media exploded with reactions as people worldwide grappled with the unexpected loss.

But amid the flood of touching tributes to the “Black Panther” star, whose four-year battle with the disease was not widely known, there was also confusion.

“Colon cancer?” one person tweeted. “Waaay too young.”

“Very strange colon cancer at such a young age?” asked another Twitter user.

“I didn’t even know you could get colon cancer that young,” another person wrote.

Such comments have concerned experts, who say they exemplify pervasive misconceptions about the risk colorectal cancer poses to people of all age groups.

“I’ve talked to many of my young patients, and they’ve told me that they never even knew about colorectal cancer before they got diagnosed,” said Kimmie Ng, director of the Young-Onset Colorectal Cancer Center at the Dana-Farber Cancer Institute in Boston.

This lack of awareness is a problem, experts say — one that is believed to be a major reason colorectal cancer is usually not caught in young people until the disease has advanced into later stages where survival rates are much lower. Boseman was diagnosed in 2016 with Stage 3 colon cancer, which progressed to Stage 4 before his death Aug. 28.

“It’s an absolute tragedy,” said William Cance, the American Cancer Society’s chief medical and scientific officer. “To think that he is gone at 43 from a preventable death is so sad.”

In recent days, as colorectal cancer has gained renewed national attention, experts have been out in full force to raise awareness about the disease, which is the second-leading cause of cancer deaths in the United States for men and women combined. Experts say there are steps people can take to reduce the number of cases and deaths, including combating stigmas surrounding the illness and pushing early-detection methods.

“It’s sad that it takes a big, well-known name to succumb to this disease to bring awareness,” Ng said. “That shouldn’t be the only circumstance under which this cancer is talked about, but I do think that it has opened up the conversation in a way that I haven’t seen, and I am really hopeful that it will encourage screening and hopefully save lives in the future.”

Colorectal cancer, which causes tumors in the colon and rectum, most commonly affects people who are 50 and older. But experts have been troubled by the growing body of research showing a steady rise in the number of young people diagnosed. According to a March report from the American Cancer Society, the rate of colorectal cancer among people younger than 50 has been increasing by about 2 percent annually in recent years. In 2018, the ACS changed its guidelines to advise people to start regularly screening for colorectal cancer at 45, five years younger than the age recommended by the U.S. Preventive Services Task Force. People who are more at risk because of an inflammatory bowel disease or family history of colorectal cancer should begin even earlier.

Of the roughly 148,000 individuals who will be diagnosed with colorectal cancer this year, about 18,000 of those cases will be young people, according to the cancer society.

“Pretty soon, about a quarter of all colorectal cancers are going to be in people under the age of 50,” Ng said, “so we really need to reverse that trend now by doing the research to figure out why it’s happening.”

Why rates among young people are climbing is “the million-dollar question,” she said.

Colorectal cancer has been linked to a number of lifestyle-related risk factors, such as diet, weight and exercise, according to the ACS. There are also racial disparities in risk as rates of the cancer are higher in Black people.

But Ng said she and her colleagues have noticed that the “vast majority” of their young patients diagnosed with colorectal cancer are not obese, live active, healthy lifestyles and don’t have family histories.

“Look at Chadwick Boseman, who was in great shape, so clearly there’s something else, and what that is, is an active area of research,” she said.

Scientists are looking into processed food and the use of antibiotics as potential triggers, Cance said. He noted that the human microbiome has been particularly intriguing to researchers.

In the meantime, though, experts say awareness and education are critical.

“We’ve been really trying to educate both patients and health-care providers that this is a phenomenon,” said Robin Mendelsohn, co-director of the Center for Young Onset Colorectal Cancer at Memorial Sloan Kettering Cancer Center in New York. “If you do have symptoms, it’s so important, first of all, not to be ashamed of them and to talk to your providers about them, and for providers to know that this is an entity so that patients can be promptly evaluated appropriately.”

Here’s how experts say we — both patients and doctors — can work to prevent deaths from colon cancer.

Normalize conversations: Not many people feel completely comfortable talking about the symptoms associated with colorectal cancer, even during doctors’ visits, said Cance, a surgical oncologist. Common symptoms include a persistent change in bowel movements such as diarrhea or constipation, rectal bleeding or bloody stool, persistent abdominal discomfort, weakness or fatigue and unexplained weight loss, according to the Mayo Clinic.

“You’re talking about changing bowel habits,” he said. “ ‘I have blood in my stool. I’m constipated today and then I have diarrhea tomorrow.’ It’s so personal.”

That reticence to discuss symptoms may play a role in delayed diagnosis.

“The time to treatment for someone less than 50 ranges from 217 to 271 days versus 29 days for older than 50,” Cance said. “The biggest gap is initial presentation to the doctor, and that’s where embarrassment stigma comes in.”

Mendelsohn recommended treating bowel symptoms like a cough or a rash.

“Those things people are always willing to talk to their doctors about and willing to ask their friends about,” she said.

Ng said she has urged fellow health-care providers to incorporate questions about bowel symptoms into their routine conversations with patients, so people don’t have to wrestle with bringing up the subject themselves.

Don’t dismiss persistent symptoms: Another reason diagnosis may be more delayed in younger patients is that they often don’t take the telltale symptoms seriously, said Andrea Cercek, co-director of Memorial Sloan Kettering’s Center for Young Onset Colorectal Cancer.

“Many are starting families, raising families, in careers, leading busy lives and just because of that, dismiss their symptoms,” said Cercek, a medical oncologist. “We can all admit that we’re guilty of postponing that exam or the doctor’s visit because something came up at work, because we had an important event to plan for or to attend.”

Mendelsohn added that oftentimes young people with colorectal cancer are otherwise healthy.

“The idea is, ‘Oh I’m young. There’s no way I can have colorectal cancer, so I’m just going to keep on doing what I’m doing and no need to talk to anyone about it,’ ” she said.

It doesn’t help that the symptoms are also more commonly due to benign conditions, which can lead some health-care providers to misdiagnose their patients, Ng said.

“When they see somebody young and healthy in front of them with some of these nonspecific symptoms, cancer doesn’t immediately come to mind,” she said.

But persistent symptoms should be seen as a sign that it may be cancer, Cance said.

“If it’s persistent, don’t wait months to get seen,” he said. “Be seen in weeks and advocate for being screened by the readily available tests and follow up.”

Know the importance of screening: Data have shown a decrease in rates of colorectal cancer among people 65 and older, which is probably due to more regular screening, experts said. Screening can be done through stool tests or a colonoscopy, which is considered the “gold standard” method, said Mendelsohn, a gastroenterologist.

Though a colonoscopy is an invasive procedure that involves cleansing your colon beforehand and being put under anesthesia, Mendelsohn stressed that the risk of major complications is low.

When colorectal cancer is caught in Stage 1, Cercek said, survival chances are in the “mid-90s.” By the time it progresses to Stage 3, the rate is between 60 and 80 percent, and treatment usually involves chemotherapy. At Stage 4, chances drop to between 10 and 20 percent.

But there is currently no routine screening for young people without symptoms, Ng said.

“It’s just not logistically possible or feasible to screen every single person the minute they turn 18,” she said. “We really need a better understanding of the science and the biology so that we can identify the high-risk group.”

Cance said he hopes Boseman’s death will galvanize more people to get screened. In recent days, Mendelsohn said her center has been getting more requests for colonoscopies than normal across all age groups, though she noted that the uptick cannot be definitively linked to Boseman. She also said the number of requests is still below what experts want to be seeing.

“In the end, for screening, we always say the best test is the one that gets done,” Mendelsohn said.

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