While largely preventable with early detection, 1 in 3 eligible Americans have never been screened for colorectal cancer. [1] March is Colorectal Cancer Awareness Month and here are important clarifications on the common misconceptions around colorectal cancer.

  1. Misconception: Cancer is not preventable. A screening test can only detect cancer, it cannot prevent cancer.

Cancer develops due to the uncontrolled division of the cells in the human body. Some cancer types, such as colorectal cancer, take 5-20 years to develop, while other cancers evolve much more rapidly. Over the decades, we have seen fewer people diagnosed with certain cancers due to the implementation of screening methods that detect precancerous lesions that are precursors to cancer. One example is cervical cancer screening. The widespread adoption of pap smears, which can detect pre-cancer, has transformed cervical cancer from one of the top cancer killers for women into a mostly prevented cancer. Mortality from cervical cancer has reduced by 75% in the last 50 years. [2]

  1. Misconception: Colorectal cancer is not a problem to our society because we have colonoscopy screening.

Most colon cancer starts as pre-cancer lesions knows as adenomas. These can be detected and removed using colonoscopy, preventing colorectal cancer.

This is why U.S. screening guidelines recommend routine colon cancer screening for 125 million Americans 45 years and older. [3] Yet, 60% of colon cancer is diagnosed after the colorectal cancer has already spread. The survival rates for patients who are diagnosed after the disease has spread to distant organs is 14%. [4]


Colorectal cancer is unfortunately the number 2 cancer killer in the U.S., causing 50,000 deaths annually. [5] The American Cancer Society expects that over 140,000 Americans will be diagnosed with colorectal cancer in 2019.

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  1. Misconception: Colonoscopy for screening is good enough as a testing option.

Although colonoscopy is very effective for finding and removing pre-cancers, less than 40% [6] of eligible individuals take this test for screening. This is because colonoscopy is invasive and inconvenient, requiring bowel prep.

  1. Misconception: I can use home stool tests I see advertised on TV for colon cancer screening.

Indeed, there are home stool tests available for screening. However, consumers should be careful as these stool tests miss 60%-75% of pre-cancers [7] that have a greater than 25% probability of becoming cancer. [8]

  1. Misconception: A blood test cannot be used for colon cancer screening.

Multiple patient surveys show that an overwhelming majority of individuals prefer a blood test over stool test or colonoscopy. [9] Unfortunately, there is no accurate blood test today for the detection of colorectal cancer and pre-cancer.

Close to U.S. $ 2.5 billion has been invested in developing blood tests for early cancer detection, including for colorectal cancer. Most of these technologies analyze DNA fragments in blood. However, none of these techniques have been able to demonstrate high accuracy for detection of pre-cancer.

A different approach, however, has shown some promise. Colorectal cancer and pre-cancers shed cells into the blood. The presence of these cells is thus a marker for pre-cancer and cancer. However, these cells are rare and until now, no technology was able to detect these cells in blood. One test, FirstSight developed by CellMax Life, detects such cells in a small blood sample drawn at the doctor?s office. Results on the performance of the test in 737 individuals were recently presented at the American Society of Clinical Oncology?s conference held in San Francisco, in January 2019.

The test showed 90% accuracy for detecting pre-cancer and 96% accuracy for colorectal cancer. A larger study is underway in partnership with Stanford, Palo Alto Veterans Hospital, Johns Hopkins and USC Keck School of Medicine. The primary goal of the study is to assess the performance of the FirstSight test US population, compared to colonoscopy.

  1. Misconception: I don?t have a family history of colorectal cancer so I don?t really need to get screened.

2 in 3 patients diagnosed with colorectal cancer do not have a family history of colon cancer. And only 5% of yearly colon cancer cases in the United States are due to a “cancer gene”. [10]

  1. Misconception: I don?t need to start screening until I am older.

In 2018, the American Cancer Society (ACS) lowered the age to start colorectal cancer screening from 50 to 45 for average risk individuals, meaning those individuals that do not have a genetic risk for colorectal cancer. Colorectal cancer incidence has declined steadily over the past two decades in the population aged 50 years and older?but there has been about a 51%?increase?in CRC among those younger than 50 years since 1994. [11] A recent analysis found that adults born around 1990 have twice the risk of colon cancer and four times the risk of rectal cancer compared with adults born around 1950, who have the lowest risk.

Tips for Colorectal Cancer Prevention
Colorectal cancer can be prevented with the following steps:

  • A healthy diet rich in fruits and vegetables
  • Reduced consumption of alcohol, red and processed meat
  • Regular physical exercise
  • Maintaining a healthy body weight

If you have a personal or family history of cancer, you and 1st degree relatives may benefit from genetic testing for mutations that confer increased risk for cancer. If these mutations are found, your doctor may recommend more frequency colon cancer screening to detect pre-cancers and cancers at an early stage.

Even if you have no personal or family history of cancer, regular colon cancer screening starting the age 45 years, is a must for reducing both the risk of colon cancer.

[1] Centers for Disease Control and Prevention
[2] National Institutes of Health. Cervical Cancer.?NIH Consensus Statement.?1996
[3] American Cancer Society, 2018 Colorectal Cancer Screening Guidelines
[4] 2017 US Census Bureau. American Cancer Society; Cancer Facts and Figures 2018.
[5] Inadomi et al, 2012
[6] Imperiale 2014
[7] Bonnington et al 2016
[8] BMC Gastroenterology, 2014
[9] American Cancer Society
[10] Wolff et al, CA Cancer J Clin 2018

Last Editorial Review: March 16, 2019

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