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Colorectal Cancer Awareness Month: Risk Factors and Screening Options

As many know, this is Colorectal Cancer Awareness Month. I’m someone who has spent most of my career working to understand and treat colorectal cancer, so for me it takes on special meaning. But the significance runs deeper than that, and is particularly personal, because my family has experienced a long history of colorectal cancer; I had my own first colonoscopy as a precautionary measure when I was in my late 20s, and have now had a total of six. Although my circumstances are unusual, I feel everyone should be aware of the risks posed by this devastating disease.

Colorectal cancer (CRC) remains a major public health problem in the United States and throughout the world. In 2021, an estimated 150,000 new CRC cases will be diagnosed in the U.S., resulting in nearly 53,000 deaths, making it the second most-common cause of cancer deaths. Globally, CRC will be diagnosed in approximately 1.2 million individuals and lead to more than 600,000 deaths.

The good news is that over the past decade and a half, there has been a significant reduction in colorectal cancer mortality in adults over the age of 55. Unfortunately, during this same period, the incidence of CRC has risen quite dramatically in individuals younger than 50. By 2023, it is estimated, 11% of all colon cancers and nearly 23% of all rectal cancers will be diagnosed in people under 50. Disturbingly, there has also been a parallel increase in death rates by 1% each year in adults under the age of 55. The reasons for this remain unclear and are the subject of continued research.

What Are the Main Risk Factors for CRC?

The typical symptoms of CRC include fatigue, reduced energy, loss of appetite, weight loss, abdominal pain or discomfort, and blood in stools or changes in the color of stools, as well as changes in stool caliber or consistency. Some patients experience no symptoms at all, which is why CRC screening is necessary.

One long-held myth is that colon cancer occurs only in individuals with a family history of the disease. In reality, it is well established that age is by far the number one risk factor. More than 90% of CRC is diagnosed in individuals older than 50, providing the basis for the long-held recommendation that CRC screening start at age 50 for average-risk individuals.

Other important risk factors include:

  • A personal history of CRC or certain types of polyps
  • A family history of CRC or familial forms of CRC
  • A history of inflammatory bowel disease (Crohn’s colitis or ulcerative colitis)

With respect to family history, an individual’s risk for developing CRC is increased two- to threefold when a first-degree relative (e.g., a parent) has the disease, increasing up to sixfold when two first-degree relatives have CRC.

Another myth is that this is a male disease; the incidence is nearly identical in men and women. Dietary intake and nutritional status are also important factors. Diets rich in processed meats, high in fat content, and low in fruits, vegetables, and dietary fiber content contribute to the increased incidence of CRC. Other risk factors include smoking, alcohol, obesity, and physical inactivity. Diabetes is believed to contribute to CRC risk, especially in individuals with type 2 diabetes.

Racial and ethnic backgrounds also play an important role in CRC risk. African Americans have the highest CRC incidence and mortality rates of all racial groups in the U.S., and the disease tends to occur at an earlier age in this patient population than in Caucasians. However, Ashkenazi Jews of Eastern European descent also have one of the highest risks for developing CRC of any ethnic group in the world.

Changes in CRC Screening

For the past 15 years, the general recommendation has been to start CRC screening at age 50 for average-risk individuals. However, with the increasing incidence of CRC in the younger population, the screening guidelines put forth by the American Cancer Society have changed. The guidelines now indicate that anyone at average risk for CRC start regular screenings at age 45. For people in good health and with a life expectancy of more than 10 years, regular CRC screenings should continue through age 75. For those between the ages of 76 and 85, screening should be based on individual preference, overall life expectancy, presence of comorbid illnesses, and previous screening history. CRC screening is not recommended for people over 85 years old.

Investigators at the Albert Einstein Cancer Center (AECC) have investigated racial and ethnic disparities in early-onset CRC. They identified more than 166,000 patients with CRC from the U.S. SEER (Surveillance, Epidemiology, and End Results) program database over the period from 1973 to 2020 with early-onset CRC (which is defined as CRC diagnosed in people under 50). Early-onset CRC was diagnosed more frequently—up to twice as often—in Blacks and Hispanics than in Caucasians. After adjusting for various common clinical features, Blacks and Hispanics had significantly lower survival rates than did Caucasians. This has become an intense area of research, as the underlying causes of this marked racial disparity are currently unclear.

AECC researchers also recently investigated the same racial and ethnic disparities in early-onset CRC in our immediate Bronx catchment area. Of nearly 650 patients who presented to the Montefiore Health System, early-onset CRC was present in 26% of Hispanics and 57.3% of Blacks, and five-year overall survival was significantly lower in these two groups than in Caucasians. These findings provide strong support for developing a race- and ethnic-specific screening strategy for patients younger than 50.

The COVID-19 pandemic has created an added difficulty for many living in these communities. On one hand, the need for CRC screening is clear. Yet venturing out to get screened presents its own risks and the potential of contracting COVID. This reinforces our need to understand and share the screening options available.

Screening Options and Strategies

There are several different options for CRC screening, and they can be divided into two types—stool-based tests and visual/structural tests of the colon and rectum.

Stool-based tests include the fecal immunohistochemical test (known as “FIT”), the guaiac-based fecal occult blood test (“gFOBT”), and a multitargeted stool test. The advantage of each is that it can be performed in the comfort of one’s home, which makes it much easier for patients. The downside is that a positive result will still require a colonoscopy to confirm the possibility of CRC.

Visual/structural tests include flexible sigmoidoscopy, CT colonography (virtual colonoscopy), and colonoscopy. I agree with most experts that the gold standard for CRC screening is colonoscopy, as it enables us to visualize directly the entire colon and rectum region, identify and remove polyps, and biopsy any large masses present. The importance of colonoscopy cannot be overstated, as the test can definitely allow for the removal of polyps—the well-established precursor lesion for CRC. It can also identify CRC at its earliest stages, when the disease can be cured in more than 90% of cases.

So when it is possible, colonoscopy is the preferred method of screening, but stool-based tests can be considered as an initial screen, especially in underserved minority communities where it may be difficult for people to get access to or schedule a colonoscopy. It is clear that a more comprehensive screening strategy will need to be developed for underserved communities, and especially for people under age 50.

This much is clear: CRC screening is absolutely critical for improving patient survival, and expanding its use is a challenge the U.S. healthcare system must meet.

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