Colonoscopies Can Prevent Colorectal Cancer

By Salina Lee, MD

Despite remarkable advances in detection and treatment of colorectal cancer, it remains the second-largest cause of cancer mortality in the United States. This statistic looms despite the fact that colorectal cancer is one of the most treatable cancers there is because early detection, thus cure, is entirely possible.

What makes this unique among the other cancers for which we have screening tools is that prevention is also possible. This is because we can identify and remove premalignant lesions before they become cancer. So what accounts for the stark contrast between this grim statistic and our known ability to prevent, detect and cure this cancer? Lack of screening. The most common signs and symptoms of early colon cancer are — nothing at all. That’s why we so strongly recommend screening for colorectal cancer.

Current guidelines recommend colorectal cancer screening for adults between the age of 50 and 75.  This may start earlier for those at higher risk (family history of colorectal cancer, chronic inflammatory bowel disease, polyposis syndromes or patients of African-American descent).

After the age of 75, we recommend screening on an individual basis. There are a variety of recommended screening tests. The gold standard is the colonoscopy, which provides both screening and prevention. Not only can it detect early stage cancers, but also precancerous lesions called polyps, can be removed to potentially prevent a cancer from developing.

Polyps are very common: About one in four people screened will have polyps, and the vast majority of polyps will never develop into a cancer. But as all cancers arise from a polyp, we remove them when we find them. If we find polyps, we recommend having a colonoscopy again in three to five years, depending on the size and number of polyps. If no polyps are found, we recommend having a colonoscopy in 10 years.

Screening age deserves second look

Important to note is the changing demographic of colorectal cancer in patients younger than 50 years old. While it’s true that over the last three decades we have seen a notable rise in the rates of colorectal cancer diagnosed in each decade prior to age 50, the significance is unclear, and no consensus on approach has been reached.

Multiple factors are in play here, including the concurrent increase in the use of colonoscopy during the same time period, the decrease in incidence in the decade immediately before the rise and the unchanged mortality rate.

This last factor may imply that cancers are not new but found at an earlier stage. Despite the rise in incidence in, for example, a person in their 20s (one case per 100,000 persons), it is still multiples times less than that of a person in their 50s (50 cases per 100,00 persons). The rates do increase stepwise across decades of life, which suggests it may be advisable to start routine screening in your 40s.

While not all medical societies have reached a consensus on new recommendations for screening, given this new information, I would encourage young people with symptoms (bleeding, rectal pain, sudden change in bowel habits or frequency) to be evaluated by a physician. Common things being common, you’re still more likely to have a nonmalignant cause, but it is important to not assume it.

Moving beyond procedural fears

Screening works. According to a 2010 study published in the journal Cancer, the incidence and mortality dropped by more than 30 percent over a 15-year period due to screening. However, in many populations, especially in rural, poor and among some ethnic groups, screening rates remain as low as 40 percent, according to a 2018 Health Services Research Administration report. Screening is still woefully underused, leaving more than 23 million adults who have gone without screening despite access to health care after the passage of the Affordable Care Act, reports the Centers for Disease Control and Prevention.

To try to close the gap in screening, an aggressive initiative was launched by the National Colorectal Cancer Roundtable and American Cancer Society in 2014 to have 80 percent of the population screened by 2018. While the results are still pending, progress has been encouraging, and it’s encouraging to know that if we can consistently increase screening rates to 80 percent, we can save more than 203,000 lives by 2030. To reach this goal, many barriers must still be overcome.

The fear of what the procedure involves remains a hurdle. While considered invasive, it’s a very routine, outpatient, one-day procedure performed under conscious sedation for comfort.

Other fears exist around the inability to tolerate the bowel preparation. Over the last few years, there has been significant improvement in the types of laxatives used in the bowel prep, with availability of much smaller-volume and better-tasting options.

Also, easing up a bit on the dietary restrictions the day before, and splitting the dose of the prep makes the process more palatable than ever. Furthermore, there are other options in screening tests including stool-based tests for microscopic evidence of blood, DNA and CT scan.

The benefit of screening tests is that they are noninvasive, yet appropriate for screening. The drawback is that they’re not preventive since they don’t allow for polyp removal. However, ultimately, the best test is the test that gets done.

Testing helps you know your risk

A common misconception is that if you live a healthy lifestyle, have no family history and have no symptoms, you are not at risk for colon cancer. While there is some evidence that engaging in a healthy diet and lifestyle may modestly reduce your risk of developing colorectal cancer, the most modifiable risk factor is failure to get screened.

Also, while a family history increases your background risk by two to three times, a lack of a family history is not protective. The lifetime risk of developing colorectal cancer is as frequent as one in 20, and the majority of patients who are newly diagnosed do not, in fact, have a family history of cancer.

Even though it’s fairly well known that signs of colon cancer may include rectal bleeding, a low blood count or change in bowel habits and stool caliber, the truth is that the most common symptom of early colon cancer is again … nothing at all. Half of those who are diagnosed after symptoms develop will die from cancer. That’s why screening is so important and cannot wait until you feel unwell.

The stakes are massive. Demystifying the process and options in colorectal cancer screening is imperative. Please join us in raising awareness for colorectal cancer throughout March. The tragedy of dying from colorectal cancer is that it is entirely treatable, curable — and even preventable.

Salina Lee, MD is an assistant professor of medicine with Rush’s Department of Internal Medicine in the Division of Gastroenterology.

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