John B. Johnson always considered himself fit. He ran track in high school and played rugby at Kent State University. At age 35, looking to get in the best shape of his life, he trained for the 2023 Cleveland Marathon, running more than 70 miles a week. One morning he saw blood in his rescue. “At first I thought it was from eating beets, but it stayed,” she says. “I felt good, but I knew I had to get it checked out.”
Johnson ran the race in 3:04, which qualified him for the Boston Marathon, and then went to the doctor. “He initially thought the bleeding was from a ruptured hemorrhoid, but ordered a colonoscopy anyway,” Johnson says. The procedure found a mass in his right colon that turned out to be stage 2 colon cancer.
Johnson was surprised. He was young, he ate clean (he had only drank one soda since he was a teenager), and he had no family history of cancer. “I just got to Boston and they told me I was sick,” Johnson says. “It didn’t make sense.”
The growing problem of colorectal cancer often affects older adults, with the average age at diagnosis being 66. However, Johnson is part of a worrying trend of people under 50 getting colon cancer, many of whom are otherwise healthy.
Colorectal cancer incidence among adults under the age of 50 increased by 3% from 2013 to 2022, with rates higher in men than in women. Research in the issue of February 17, 2026 YAMA found that mortality from colon cancer in this age group increased by 1.1% per year from 2005 to 2023. Colorectal cancer is now the 1st leading cancer killer among people under 50.
Colorectal cancer occurs in the colon or rectum, which together with the anus form the large intestine. (Colorectal cancer may be called colorectal cancer or colorectal cancer, depending on where it starts.) Early symptoms of colon cancer are sometimes denied, such as changes in bowel habits (unexplained diarrhea or constipation), rectal bleeding, and blood in the stool (red or dark and tarry). Other warnings include sudden weight loss, unexplained weakness and fatigue, lower abdominal pain, and the feeling that your bowels are not empty after passing.
All in the genes
Overweight and obesity, smoking, alcohol consumption, and a diet high in red and processed meat and low in fiber are among the main lifestyle factors associated with colon cancer. Diabetes and inflammatory bowel disease (ulcerative colitis and Crohn’s disease) also increase the risk.
However, researchers have found that more people who are doing all the healthy things are still being diagnosed. The reasons remain unclear.
One explanation may be genetics. People who have a first-degree relative (parent or sibling) with colon cancer are twice as likely to be diagnosed with colon cancer than those without a family history. Dr. Vikram Reddy, MD, PhD, Chief of Colorectal Surgery at Yale School of Medicine. If these relatives were diagnosed before the age of 50, the risk is higher. The study also found that the risk of cancer, although slightly lower, may extend to second-degree relatives (aunts, uncles, nieces, nephews, and grandparents).
However, it is a family connection associated with approximately 25% of cases. The genetic disorder is about 10%. The rest seems to happen by chance.
“Genetics may be involved in this tendency to be diagnosed in younger people, even those who are healthy,” says Dr. Reddy. “We’ve identified many genes that are associated with colon cancer, but we haven’t identified all of the genes responsible. Or it could be something else entirely.”
If people have a family history of colon cancer, genetic testing is an effective screening tool. If they have a known genetic marker, they can begin early screening and monitoring.
Whether you know your genetic risk or not, testing can be a lifesaver. Just ask Tim Hill, 36, a relief pitcher for the New York Yankees.
In 2015, he entered spring training with the Kansas City Royals as a 25-year-old power forward. He soon found that the daily exercises were tiring him out. A blood test revealed that he was anemic and his hemoglobin level was half the normal range. Anemia can be a symptom of colon cancer bleeding. It was then that Hill told his doctors that his father had died of the disease at the age of 53.
Hill was diagnosed with stage 3 cancer, but he also discovered he had Lynch syndrome, a genetic condition that affects about one in 280 people and is the most common cause of hereditary colon cancer.
As a result of the surgery, half of Hill’s hindgut, the longest part of the colon and the entire upper colon were removed. Several rounds of radiation and eight months of chemotherapy freed him from the cancer, but reduced his body from 210 to 145 kilograms. The healing process was slow, but by the time next spring training rolled around, he was back to his old self.
Hill’s story highlights the need to examine a family’s health records and take action when necessary. “My dad probably got cancer because of Lynch, but he never knew he had it, so I never thought I was in danger when my dad died in his 50s.” “Who Thinks About Cancer Risk Testing at 25?”
Capture the screen
The best defense against colon cancer, at any age, is a good crime. It starts with following healthy habits. “If you exercise, swap out unprocessed foods, red meat and pork for chicken and fish, and get enough fiber, you’re already doing all the right things to protect yourself,” says Dr. Reddy. “But you also need to be vigilant and see your doctor if you experience any new abdominal symptoms that last more than a week.”
Regular checkups are a must. Colonoscopy remains the gold standard and guidelines recommend that you have up to the age of 45. If a first-degree relative has had colon cancer, start after 40 or 10 years before the age at which the relative developed the cancer, whichever is earlier. (For example, if they were diagnosed at age 45, get tested at age 35.)
During a colonoscopy, a flexible tube with a light and camera is inserted into the end of the rectum to examine the rectum, colon, and last part of the small intestine for polyps—small growths that can develop into colon cancer. Any polyps found are removed.
“Depending on the results and your risk, you may need a repeat colonoscopy every 10, five, or even two to three years,” says Dr. Reddy. “Patients with genetic syndromes may need annual screening.”
Also, ask about genetic testing if there is a family history of colorectal cancer or if you are curious about your risk. A simple blood test is inexpensive and covered by many insurance plans, and is ordered by a doctor.
Back to the race
For Johnson, colon cancer was a painful but transformative part of her life. After 25 doses of radiation (“The worst pain I’ve ever felt”) and eight chemotherapy treatments over four months (“The worst pain I’ve ever felt”), the tumor was gone.
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. Her journey inspired her to create the Get Off My Butt Foundation to help break the silence surrounding colorectal cancer among the adult and fitness community.
Johnson’s warning: Never think you’re invincible. “Admitting something is off your body and being scrutinized isn’t a sign of weakness, it’s a sign of strength,” she says. “I was in the best shape of my life and I still have cancer. It can happen to anyone.”
