

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.
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.
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.
Risk factors for colon cancer include:
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:
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.
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.
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:
Learn more about colorectal cancer and screening at El Camino Health.
This article first appeared in the March 2025 edition of the HealthPerks newsletter.
Identify your risk factors and what to do if you are at risk.