The mortality from colorectal cancer has decreased substantially in the U.S. during the past decade. While some of the improvement is due to better cancer treatment and reduced risk factors, the largest proportion is thought due to screening. The concept that early detection saves lives has now become well recognized. The harms of screening — particularly among individuals with limited life expectancy — are less well appreciated.
Royce et al. recently published a study examining self-reported cancer screening in the five years prior to interview among individuals aged 65 years and older using data from the National Health Interview Survey from 2000-2010. They used a validated mortality index based on age, sex, smoking, body mass index, comorbidities, hospitalization and functional measures. Among individuals with very high (>75 percent) risk of dying within nine years, the colorectal cancer screening rate was 40.8 percent. For those with a > 50 percent chance of dying in five years, the colorectal cancer screening rate was the same.
There have been other reports of potential over-screening among the elderly. In a 5 percent sample of Medicare patients with a prior negative colonoscopy, Goodwin et al. found repeat colonoscopies within seven years in 45.6 percent of individuals aged 75 to 79; among those over age 80 repeat colonoscopies were performed in 32.9 percent. High rates of screening in patients with limited life expectancy will become a greater problem as the population ages.
While there is general agreement about when to start colorectal cancer screening — age 50 — there is less certainty about when to stop. Authoritative guidelines from the U.S. Preventive Services Task Force recommend against screening for colorectal cancer in adults older than age 85, and against routine screening in adults age 76 to 85 years of age. The American College of Physicians does not recommend continued screening in adults over the age of 75 or when the life expectancy is less than ten years. Life expectancy can be tricky to estimate although there are apps and websites available.
How can we explain high rates of screening in groups with limited life expectancy? Public health campaigns have done such a good job promoting screening that the idea of stopping may be new to some patients. Interviews with the elderly have found that they perceived screening tests as morally obligatory and continued screening a habit or custom. We have created such momentum for screening that recommendations to stop screening may threaten trust. Patients are skeptical about statistics used by government panels to limit screening (rationing). The situation may be even more difficult for colonoscopy screening by gastroenterologists because many of us work in open-access procedure units where we do not meet patients until they are already prepped and gowned awaiting their procedure. Having a discussion about the need for screening in a prepped patient in the endoscopy room is the wrong place and the wrong time.
There are some positive steps that the gastroenterologists could take to limit inappropriate screening. First, we could do a better job managing expectations. There are harms as well as benefits to colonoscopy. For patients with limited life expectancy, the benefits are likely to be negligible, and patients need to be educated that screening is not always an undisputed good.
Gastroenterologists need to turn off automatic call back letters for elderly patients. The decision to screen after age 75 should be a shared one between the patient and the primary care physician. Life expectancy is not simply a function of age, and decisions about screening must include comorbidities and functional status. A request for a screening colonoscopy in an elderly patient ought to prompt a conversation with the referring physician and not an automatic appointment. We might wish to qualify the language we use with younger patients. When we tell the patient that we have removed a precancerous polyp they conclude that we have saved their life even though the chance of eventual cancer from a tiny precancerous polyp is remote. It will be hard to tell the patient to stop screening when they are older because they believe their life was spared by removing a polyp before it turned into cancer. Finally, the government, through Medicare, could alter payment policies making it unattractive to perform screening colonoscopies in elderly patients. If gastroenterologists don’t take steps to limit procedures with little benefit, payors may step in.
Colonoscopy has revolutionized the practice of gastroenterology and saved countless lives. We should work tirelessly to promote colorectal cancer screening in appropriate individuals. When the harms outweigh the benefits, we need to stop.
Robert S. Sandler is a gastroenterologist. A version of this article originally appeared in AGA Perspectives.
