Colon cancer is striking younger adults at alarming rates—and a common gut bacteria may be partly to blame.

Colon cancer, also known as bowel cancer, is the third most common type of cancer, but also one of the most preventable. Early diagnosis and lifestyle changes can play a huge role in the progression of colon cancer.

Colon cancer begins in the colon, the long, muscular section of the large intestine that moves digested food toward the rectum and out of the body. It usually begins with small, noncancerous growths called polyps. These can form in the inner lining of the colon and, over time, may become cancerous tumors. If undetected, the cancer can grow through the colon wall and spread to other parts of the body through the lymphatic system or bloodstream.

Signs and Symptoms of Colon Cancer

Colon cancer can be sneaky, sometimes showing no symptoms at all in the early stages. But there are signs to watch out for:

• Blood in your stool: Red-tinged or darker stools can be a warning sign. It could be something minor like hemorrhoids, but it’s always worth checking with a doctor.

• Changes in bowel habits: If you’re experiencing constipation, diarrhea, or feeling as though your bowel hasn’t fully emptied, talk to your doctor.

• Persistent abdominal pain: Unexplained stomach pain that doesn’t go away is a red flag worth investigating.

• Bloating: A bloated stomach that lingers, worsens, or comes with vomiting or blood in the stool should not be ignored.

• Unexplained weight loss: Losing weight without any reason could be a red flag.

• Vomiting: Frequent or unexplained vomiting could signal a blockage or other serious issue.

• Fatigue or shortness of breath: These may be signs of anemia, which can be linked to colon cancer.⁽¹⁾

The Colibactin Connection

Here’s something new: Some strains of E. coli, a common gut bacteria, can produce a toxin called colibactin. This toxin can alter DNA, and researchers believe it may play a role in early-onset colon cancer.

A 2025 study published in Nature analyzed cancer tissue samples from 981 individuals across 11 countries and found that colibactin-linked DNA changes were 3.3 times more common in people diagnosed with colon cancer before age 40 compared to those diagnosed in their 70s. These changes may even begin in childhood.⁽²⁾

While more research is needed, this finding could explain the rise in colon cancer among younger adults.

Dr. Zuri Murrell, Colorectal Surgeon, Los Angeles, shares his insights on Colibactin.

Did You Know?

Most cases of early-onset colon cancer are diagnosed between the ages of 20 and 49—and often at more advanced stages.

Can You Prevent Colon Cancer?

While colon cancer isn’t entirely preventable, you can significantly reduce your risk through a few key lifestyle changes:

• Don’t smoke. If you do, ask your doctor about quitting.

• Avoid or limit alcohol consumption to moderate levels.

• Stay active and maintain a healthy weight.

• Eat a healthy diet. Add fruits, veggies, whole grains, and cut back on red meat and processed foods. Drinking coffee may also help.

• Know your family history. If colon cancer runs in your family, let your healthcare provider know. You may need more frequent screenings.

• Get screened! Colonoscopy and other screening tests can catch precancerous polyps early, when they’re easiest to treat.

Final Thoughts

Colon cancer is serious, but with awareness, early diagnosis, and healthy habits, it’s also highly preventable. Stay informed, know your body, and don’t hesitate to reach out to a healthcare provider with any concerns.

References:

1. “Colorectal (Colon) Cancer”, Cleveland Clinic, Last Modified on 14/11/2022, https://my.clevelandclinic.org/health/diseases/14501-colorectal-colon-cancer#prevention

2. Tim Gunn, “ E. coli toxin could be linked to rising rates of bowel cancer in younger adults”, Cancer Research UK, Last modified on 24/4/2025, https://news.cancerresearchuk.org/2025/04/23/colibactin-e-coli-early-onset-bowel-cancer/

(Rehash/Dr. Hansini Bhaskaran/MSM)