There’s good reason why 50 is that “magical” number for when a typical person should begin getting colonoscopies for colon cancer screening.

A colonoscopy is a minimally invasive procedure that can detect colon cancer, or precancerous polyps.

“Colon cancer is generally a disease of the elderly,” says Mitchell S. Cappell, MD, Chief, Division of Gastroenterology & Hepatology, William Beaumont Hospital, Royal Oak, MI.

“Nearly 95 percent of colon cancers occur in people more than 50 years old.

“This phenomenon is due to the fact that colon cancer generally comes from chance biochemical abnormalities, called mutations, in the genes (DNA) of individual colon cells.”

Colon cancer (like all malignancies) does not happen overnight; there are a number of stages of transformation that a healthy cell undergoes before it becomes a malignant cell.

In the case of colon cancer, a normal cell, due to accumulated mutations, will proliferate out of control, initially forming a benign polyp – which a colonoscopy can detect. On the spot, the physician removes the polyp(s).

If you don’t have screening for colon cancer, the polyp will continue growing and may sustain more mutations – enough to morph it into a malignant tumor.

Dr. Cappell explains that this disease “occurs mostly in the elderly because this sequence of changes, the accumulation of chance mutations, is a long process that takes many years.”

This doesn’t mean that people younger than 50 or 45 are immune to colon cancer.

Dr. Cappell adds, “About 2 percent of people developing colon cancer are younger than 40 years old.

About 20 percent of people who develop colon cancer when less than 40 years old have special risk factors that place the patient at a very high risk of developing colon cancer.”

These risk factors are 1) familial polyposis coli (abbreviated as FPC), and 2) Lynch syndrome (also called HNPCC).

In FPC, patients have many benign polyps, and malignancy is likely because out of so many polyps, it’s inevitable that one or more will become malignant.

In Lynch syndrome, the patient develops just a few benign polyps, but these particular polyps have an intrinsically high risk of morphing into colon cancer.

“Patients less than 50 years old generally do not undergo screening for colon cancer because they have much lower risks than patients more than 50 years old,” continues Dr. Cappell.

If someone is diagnosed with FPC or Lynch syndrome, he or she will be urged to have colonoscopies beginning at a much younger age.

For reasons not known, blacks have a higher risk of colon cancer, and thus, are urged by the American College of Gastroenterology to begin screening at age 45.

Just how young can a person getting a colonoscopy be?

Dr. Cappell says, “Patients with a close blood relative with familial polyposis coli need colonoscopy at a young age, during their early teens, to diagnose or exclude this disorder.

“Likewise, close blood relatives of patients with Lynch syndrome need early colonoscopy beginning in their mid-20s.

“Patients with a family history of colon cancer in first degree relatives (e.g., mother or father) should generally undergo colonoscopy at age 40 years or earlier.”

So if you’re 25 and have no family history of this dreadful disease, and do not have Lynch syndrome or FPC, this does not give you the green light to practice lifestyle habits that are risk factors for colon cancer, such as:

1) a sedentary lifestyle, 2) a meat-based diet, 3) eating lots of processed meats, 4) diet low in fiber, high in “bad” fats, and 5) smoking and heavy drinking.

You have no green light because, as Dr. Cappell explains, colon cancer (in the absence of Lynch syndrome or FPC) is decades in the making, and how you treat your body during your younger years influences your risk of developing the disease.

Dr. Cappell says, “In summary, colon cancer usually occurs in patients more than 50 years old, and colon cancer is unusual in patients less than 50 years old.  However, no age group is immune from colon cancer.

“I saw and diagnosed one patient with incurable colon cancer at age 20, a few weeks before his planned wedding.”

Symptoms of this Common Disease

Constipation, diarrhea, and especially with a recent dramatic shift in bowel movements (such as from regular bowel movements to constipation); blood in the stools (may be bright red, or tar-like); abdominal pain; abdominal bloating; unexplained weight loss; unexplained fatigue; and appetite suppression.

Note: Having some of these symptoms doesn’t mean you have the disease.

In fact, the symptoms of irritable bowel syndrome can be very similar, though over time, in untreated colon cancer, the symptoms will get worse.

“Colon cancer may also present as anemia due to iron deficiency unexplained by blood loss during menstrual periods or by numerous childbirths,” says Dr. Cappell.

“Patients should routinely undergo screening colonoscopy at age 50 years even without symptoms or risk factors for colon cancer.”

Recommended Age to Begin Screening for Colon Cancer Drops in May of 2021

According to the U.S. Preventive Services Task Force, the age for a person’s first screening (assuming they are of average risk) is 45.

dr. cappell
Dr. Cappell has been in practice for over 30 years.
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.  


Top image: Cancer Research UK