John B. Johnson has always considered himself fit. He ran track in high school and played rugby at Kent State University. At 35, wanting to get in the best shape of his life, he trained for the 2023 Cleveland Marathon, racking up 70-plus miles per week. One morning, he noticed blood in his stool. “At first, I thought it was from eating beets, but it persisted,” he says. “I felt fine but knew I should get it checked out.”
Johnson ran the race in 3:04, which qualified him for the Boston Marathon, then saw his doctor. “He initially thought the blood was caused by a ruptured hemorrhoid, but still ordered a colonoscopy,” says Johnson. The procedure found a mass in his rectum that proved to be stage 2 colorectal cancer.
Johnson was shocked. He was young, ate clean (he hadn’t drunk a soda since his teens), and had no known cancer in his family. “I just got into Boston, and they told me I was sick,” says Johnson. “It didn’t make sense.”
A rising problem Colorectal cancer often strikes older adults, with 66 being the median age at diagnosis. However, Johnson is part of an alarming trend of people under 50 getting colorectal cancer, many of whom are otherwise healthy.
Colorectal cancer cases increased 3% per year from 2013 to 2022 among adults younger than age 50, with rates higher in men than in women. A study in the Feb. 17, 2026 issue of JAMA found that colorectal cancer deaths in this age group rose 1.1% per year from 2005 to 2023. Colorectal cancer is now the No. 1 fatal cancer among those under 50.
Colorectal cancer originates in the colon or the rectum, which together with the anus make up the large intestine. (Colorectal cancer may be referred to as colon cancer or rectal cancer, depending on where it began.) Early signs of colorectal cancer are sometimes dismissed, such as changes in bowel habits (unexplained diarrhea or constipation), rectal bleeding, and blood in your stool (bright red or dark and tarry). Other warnings include sudden weight loss, unexplained weakness and fatigue, cramping pain in the lower abdomen, and a feeling that your bowel isn’t empty after passing stools.
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All in the genes
Excess weight and obesity, smoking, heavy alcohol use, and a diet high in red and processed meat and low in fiber are the main lifestyle factors linked with colorectal cancer. Diabetes and inflammatory bowel disease (ulcerative colitis and Crohn’s disease) also raise the risk.
However, researchers are finding that more people who do all the healthy things are still being diagnosed. The reasons remain unclear.
One explanation may be genetics. People with a first-degree relative (parents or siblings) with colorectal cancer have double the risk of getting the disease than those with no family history, according to Dr. Vikram Reddy, MD, PhD, chief of colon and rectal surgery at Yale School of Medicine. The risk is greater if that relative was diagnosed before age 50. Research has also found that the cancer threat, although somewhat lower, may extend to second-degree relatives (aunts, uncles, nieces, nephews, and grandparents).
Yet, family connection is associated with about 25% of cases. Inherited genetic disorders make up approximately 10%. The rest seems to occur by chance.
“Genetics may be tied to this trend of younger people being diagnosed, even those who are healthy,” says Dr. Reddy. “We’ve identified many genes linked with colorectal cancer, but we haven’t identified all the genes responsible. Or it could prove to be something else entirely.”
If people have a family history of colorectal cancer, genetic testing is an effective screening tool. If they carry a known genetic marker, they can begin early screening and monitoring.
Whether or not you know your genetic risk, testing can be a lifesaver. Just ask Tim Hill, 36, a relief pitcher for the New York Yankees.
In 2015, he arrived at spring training with the Kansas City Royals as an energetic 25-year-old. He quickly found that the daily workouts left him exhausted. A blood test revealed he was anemic with hemoglobin levels at half the normal number. Anemia can be a sign of tumor bleeding from colorectal cancer. That’s when Hill told his doctors that his father died from the disease at age 53.
Hill was diagnosed with stage 3 cancer, but he also discovered he had Lynch Syndrome, an inherited genetic condition affecting about one in 280 people, and the most common cause of hereditary colorectal cancer.
Surgery removed half of Hill’s transverse colon, the longest part of the large intestine, and the entire ascending colon. Several rounds of radiation and eight months of chemotherapy left him cancer-free, but shrunk his body from 210 to 145 pounds. The healing process was slow, but when the next spring training rolled around, he was back to his robust former self.
Hill’s story underscores the need to scrutinize one’s family health records and take action when needed. “My father most likely got cancer because of Lynch, but he never knew he had it, so I never thought I was in danger even though my dad was in his early 50s when he died,” he says. “Who thinks about checking for cancer risk when they’re 25?”
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Getting screened
The best defense against colorectal cancer, at any age, is a good offense. It begins with sticking to healthy habits. “If you’re exercising, eating unprocessed foods, switching out red meat and pork for chicken and fish, and getting enough fiber, you’re already doing all the right things to protect yourself,” says Dr. Reddy. “But you also need to stay vigilant and see your doctor if you experience any new abdominal symptoms that linger for more than a week.”
Routine screening is a must. A colonoscopy remains the gold standard, and guidelines recommend having one by age 45. If a first-degree relative had colorectal cancer, begin at 40, or 10 years before the age at which the relative developed cancer, whichever is earlier. (For example, if they were diagnosed at age 45, get screened at 35.)
During a colonoscopy, a flexible tube with a light and a camera at the tip is inserted through the rectum to examine the rectum, colon, and the last part of the small intestine for polyps—small growths that can develop into colorectal cancer. Any found polyps are removed.
“Depending on your results and your risk, you may need repeat colonoscopies every 10, five, or even two to three years,” says Dr. Reddy. “Patients with genetic syndromes may need annual screening.”
Also, inquire about genetic testing if colorectal cancer runs in the family, or if you’re curious about your risk. The simple blood test is inexpensive and covered by many insurance plans when prescribed by your doctor.
Back in the race
For Johnson, colorectal cancer was an agonizing, but transforming, part of his life. After 25 doses of radiation (“The worst pain I’ve ever felt”) and eight chemotherapy treatments over four months (“The sickest I’ve ever felt”), the tumor vanished.
In 2025, he ran Boston, matching his time from the Cleveland Marathon. A month later, he ran Cleveland again, two years after his diagnosis, and broke the three-hour mark. His journey inspired him to launch the Get Off My Butt Foundation to help break the silence around colorectal cancer among young adults and the fitness community.
Johnson’s warning: Never think you are invincible. “Admitting something is off with your body, and getting checked, is not a sign of weakness, but a mark of strength,” he says. “I was in the best shape of my life, and I still got cancer. It can happen to anyone.”
