I wasn’t sure what sort of catchy title I could give to this article … I considered (but rejected) “preventing death from below”. So I will just go straight to the content: Colorectal cancer is the second leading cause of cancer death in the United States.
Most physicians try to impart this message to their patients (as did KATIE COURIC on The Today Show) but recent statistics indicate that this cancer stat has not been overwhelmingly noted or acted upon. A third of eligible adults in the United States have never been screened for colorectal cancer! The June 21st issue of JAMA has three articles that list the new recommendations by the US Preventive Services Task Force (USPSTF) and a review of the current screening tests for colorectal cancer. So I thought I might share them with you…
In 2016 an estimated 134,000 persons will be diagnosed with colorectal cancer and 49,000 will die from it. Colorectal cancer is most frequently diagnosed among adults aged 65 to 74 and the median age at death is 68; way too young…We are supposed to start screening at age 50 and continue until age 75 provided there’s no significant family history of colorectal cancer. The USPTF now states that the decision to screen in adults aged 76 to 85 should be an individual one depending on a person’s overall health and previous screening history. (If other diseases are present which compromise health and/or previous screening was negative, there is probably no need to do further testing.)
Available testing includes colonoscopy, flexible sigmoidoscopy, computed tomography colonography (virtual colonoscopy), fecal occult blood test, and fecal immunochemical test (the latter two check for blood in the stool, but immunochemical testing does not require a special no-meat diet ). Finally there is now a multi-targeted stool DNA test which checks for cellular mutations indicative of cancer as well as occult blood. All these reduce the incidence of, and mortality from, colorectal cancer.
How often to test, which ones to use and what works best are issues that are still being investigated through multiple studies. These factors were reviewed in the articles with multiple charts and graphs but I thought that the one that was most relevant was the one that calculated life years gained per thousand individual screens. Here is the list from best to “less best”:
Colonoscopy every 10 years
Stool test for DNA mutations and occult blood every year
Flexible sigmoidoscopy every 10 years plus stool test for occult blood every year
Virtual colonoscopy every five years
Stool test for a occult blood every year
Stool test for DNA mutations and occult blood every three years
Flexible sigmoidoscopy every five years
All of the articles in this issue of JAMA emphasize that colonoscopy is considered the gold standard, especially when comparing outcomes of other colorectal screening tests. However, it is more invasive and there can be complications such as perforation and bleeding as well as “over diagnosis” which result in unnecessary treatment for small lesions that are not precursors to cancer. There is good evidence that the less invasive virtual colonoscopy detects colorectal cancer and large potential precursor lesions. But if a lesion is found, the patient has to undergo regular colonoscopy to get a biopsy or to excise the lesion. There is some concern about exposure to low dose radiation with virtual colonoscopy. The radiation dose in this type of scan is decreasing as new systems are developed but it is still about twice that of exposure from yearly background sources in the US. Having a virtual colonoscopy every five years could cumulatively contribute to a small increased risk of cancer. The radiologists and GI experts do not, however seem to be overly concerned and state that they want more empirical evidence. For those who wish to abstain from any exam that requires a “prep” (solutions that cause severe diarrhea and/or enemas) testing with special stool tests on a regular schedule can also detect suspicious lesions. But of course, if the test reveals blood or abnormal cells a diagnostic colonoscopy is necessary to rule out (or in) cancer.
There is ample evidence that early diagnosis of a pre-cancerous polyp or an early cancer saves lives. It would be horrifying to suffer from a stage four colorectal cancer knowing that screening might have prevented this late diagnosis. My goal as a physician has been to prevent this. And as each of us assume more and more responsibility for our own health care we have to understand and act on these recommendations to appropriately screen for this disease.