Colon Cancer: The Most Common Questions

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It's essential to know the basics of colon cancer to protect your health. We’ve put together this set of questions to provide you with a topline on this too-common disease.

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What accounts for the rising incidence of colorectal cancers in younger adults?

The short answer is, we don’t know – yet. Researchers are looking into several theories. Environmental pollutants may be altering the gut microbiome, increasing the risk of developing cancer. Some scientists are looking into triclosan, an antibacterial agent that was used in soap and toothpaste until it was banned in 2016. Microplastics are another possible suspect: the rise in colon cancer in younger people roughly tracks with the increase in microplastics in our bodies. Still another theory is chronic exposure to pollution of the air, soil, and water.

What about older people? Are their colorectal cancer rates going up as well?

Colon cancer rates in people 65 and older have stabilized for one simple reason: they get regular colonoscopies. Cancers and precancerous growths are discovered early and removed during the procedure.

What are the risk factors for developing colon cancer?

Risk factors for colon cancer include:

• Excess weight
• Smoking
• Heavy alcohol use
• A diet low in fiber and high in fat and processed food
• A sedentary lifestyle
• Family history of colorectal cancer in a first degree relative (parent, sibling, child) – this could be due to genetics or, if the affected relatives all live in the same area, environmental pollutants
• Diseases that cause inflammation in the gut, such as Crohn’s, IBS, and diabetes

What are the symptoms of colon cancer?

Early-stage colon cancer rarely has symptoms. That’s one of the reasons it’s essential to have regular colonoscopies — symptoms don’t usually develop until the cancer is at stage 3 or 4. Consult your physician if you are experiencing any of the below symptoms:

• Changes in bowel habits that last longer than a few days (constipation diarrhea, stool appearance)
• Rectal bleeding (bright red blood) or blood in stool
• Persistent abdominal pain, gas, or cramping
• Unintentional weight loss
• Fatigue and weakness
• Persistent urge to have a bowel movement, even after using the bathroom

What is a colonoscopy like?

A colonoscopy uses an endoscope, a flexible tube with a lighted camera on the end, to examine the inside of your large intestine, including the colon, rectum, and anus. The procedure may be preventive as a part of a wellness screening, diagnostic to determine the cause of certain symptoms, or therapeutic to remove polyps or suspicious tissues.

For the colonoscopy to yield clear results, your colon must be absolutely empty. This requires drinking a laxative medication called a bowel prep. The prep will cause diarrhea as your colon empties out completely. Plan on staying home as you will be making frequent trips to the bathroom. When you go in for your colonoscopy the next day, you'll be given monitored anesthesia care (MAC), a combination of medications that provide sedation, pain relief, and muscle relaxation. In some cases, general anesthesia may be used.

Once you are unconscious, the doctor will insert the endoscope through your anus into your rectum and colon, guiding the device all the way up to where your colon meets your small intestine. The camera transmits video of the inside of your colon to a monitor in real time and the catheter pumps air into your colon to inflate it, making it easier to see details of the bowel walls. Your provider will scan the monitor for anything abnormal. They identify and remove any polyps or abnormalities, which are then biopsied. Even if a polyp contains cancer cells, no further treatment will be needed as long as the cancer hasn’t spread. This is the preventive aspect of the procedure: polyps that could eventually become malignant are removed. When the camera reaches the end of your colon, your provider will slowly pull it back out, carefully watching the screen a second time.

You will wake up about an hour after a colonoscopy but the anesthesia can take a full day to wear off. You should arrange for transportation home.

What is a polyp?

A polyp is a growth that protrudes from the surface of an organ or membrane. Polyps can occur in various parts of the body, including the colon and rectum. While most polyps are benign, some can develop into cancer over time. About 30% of men and 25% of women over 45 have precancerous colon polyps. These growths are found in about 30% of preventive colonoscopies. Removing them during the exam is standard procedure.

Following the Guidelines

The American Cancer Society recommends a first colorectal cancer screening at age 45 for people of average risk. Continue to have screenings as recommended by your doctor through age 75. For those above 75, the decision to be screened should be based on life expectancy, overall health, previous screening results, and personal choice. People over 85 no longer need to get screened. More frequent screenings, as recommended by your physicians, are prescribed if you have:

• A personal history of colorectal cancer or certain types of polyps
• A family history of colorectal cancer
• A personal history of inflammatory bowel disease (ulcerative colitis or Crohn’s disease)
• A confirmed or suspected hereditary colorectal cancer syndrome, such as familial adenomatous polyposis (FAP) or Lynch syndrome (hereditary non-polyposis colon cancer or HNPCC)
• A personal history of radiation to the belly or pelvic area to treat a prior cancer

Learn more about colorectal cancer and screening at El Camino Health.

This article first appeared in the March 2025 edition of the HealthPerks newsletter.