As a practicing gastroenterologist, I never want to say to a patient: “You have advanced colon cancer.” Just last week, I discovered an early colon cancer in an asymptomatic patient who was referred to me after a positive result on a non-invasive multi-target stool DNA test. The patient was grateful we caught it and recognized that if it was not for that positive test, she was hesitant to have a colonoscopy, and her cancer could have been caught too late.
Colorectal cancer is the second most common cause of cancer death in the United States. It is also very preventable. We know that the best way to improve outcomes for patients is to find and remove precancerous polyps in the colon and to detect cancers early when treatment interventions are most effective. Compared with most other cancers, we are fortunate to have effective tests for colorectal cancer screening, detection, and prevention.
We have made real progress with colorectal cancer screening, but much work remains to be done as nearly one in three screen-eligible adults is not up to date with current guideline recommendations. The United States Preventive Services Task Force and American Cancer Society guidelines recommend regular colorectal cancer screening for everyone age 45 and older who is at average risk for the disease. In the last 20 years, screening rates have increased – in part due to the availability of non-invasive stool tests in addition to colonoscopy. The incidence and death rates from colorectal cancer have declined by 35 and 40 percent, respectively. These percentages need to be better. An estimated 60 million people in this country, ages 45 to 80, remain unscreened. We must close this gap by expanding the use of proven cancer detection strategies, especially among populations where there are striking disparities, and with continued innovation in cancer detection tools.
As a gastroenterologist who recommends and performs colorectal cancer screening, if a patient prefers a non-invasive test, I want to recommend the most accurate and reliable test currently available.
Blood tests for colorectal cancer have gotten a lot of attention this year and will have a role to play in closing the colorectal cancer screening gap. Different non-invasive screening modalities allow for more individuals to get screened, which is critical in colon cancer prevention. However, we need additional guidelines for when blood tests and other screening methods should be used and for which patients.
The United States Preventive Services Task Force currently recommends several screening options for colorectal cancer, giving people choices that work best for their lives and circumstances. These include colonoscopy; Cologuard®, a non-invasive test that measures tumor-associated markers in the stool and can be taken at home; or a fecal immunochemical test – or FIT – which tests for the presence of blood in the stool, a potential sign of cancer. We know these tests work. Colonoscopy and Cologuard detect more than 90 percent of colorectal cancers (95 percent and 92 percent, respectively) and have also been shown to detect pre-cancerous lesions, which is key to cancer prevention.
Some patients do face challenges in having a colonoscopy including taking the cleansing preparations the day before the test, taking time from work, arranging childcare or caring for a family member, or finding someone to accompany them home after the procedure. A non-invasive screening option is so important and has made a difference for patients who may not have otherwise had a colonoscopy but needed to do so. New data published earlier this year in the New England Journal of Medicine showed that a next-generation version of Cologuard continued to improve the performance of that test – detecting 94 percent of cancers and 43 percent of pre-cancerous lesions – and outperformed FIT in detecting cancers and pre-cancers. Importantly, the study population was diverse and reflective of the U.S. population regarding race and ethnicity.
In the same issue of the New England Journal of Medicine, data showed the blood test detected only 83 percent of cancers and 13 percent of pre-cancerous lesions. The goal when screening is early detection. These lower numbers may mean that we could be missing more patients with colon cancer and pre-cancerous lesions.
I am optimistic about our ability to continue expanding screening through innovation, but we must do so responsibly. As the U.S. Preventive Services Task Force and other groups consider the future of colorectal screening, it is critical that guidance reflects the need for new methods to improve our ability to detect and prevent colorectal cancer. We cannot go backward.
As a clinician, I want to tell more patients that we caught their cancer early or possibly prevented their cancer from forming. Through innovation and the responsible use of new or improved colorectal cancer screening tests, we will continue to make meaningful progress against this very common disease.
Dominique E. Howard is a gastroenterologist.
