Colonoscopy gets no respect. Virtually everyone seems to acknowledge its worth, yet its value has been based mostly on expert consensus and observational studies. Screening for colon cancer should be a slam-dunk argument—1/20 people will have colon cancer in their lifetime, there are no symptoms until the cancer is advanced, and early lesions are easy to remove. Despite this, no one is eager to have it done and I suspect it contributes to a spike in blood pressure during physical exams of 50 year olds.
Colonscopy gets so little respect that even a recent study that shows colonoscopy reduces the chance of dying from colon cancer by 53% generated little popular attention. A study by Zauber et al. has shown that relative to a similar comparison group, patients who were randomized to a strict colonoscopy screening group reduced their chance of dying from colon cancer by 53%, giving some of the first clear evidence that colonoscopy reduces mortality.1 The problem with this study was that the 53% reduction was based on a population that had 100% compliance with colonoscopy, which everyone knows isn’t happening. A study by Quintero et al. compared detection rates of colonoscopy with detection rates by fecal occult blood testing. Colonoscopy was clearly the superior test, especially for adenomas, as a colonoscopy strategy detected roughly twice as many advanced adenomas as fecal occult blood testing. However, overall fecal occult blood testing detected the same number of colon cancers as more people actually followed through with the fecal occult blood testing than with the colonoscopy.2 The bottom line is that there is now evidence that colonoscopy dramatically reduces the chance of dying from colon cancer—if you actually get it done.