Age to stop?

Case description

Rachel, a 75-year-old woman, is checking in for a routine visit. Sitting outside the office door is Rachel’s 78-year-old husband, whom you last saw a few months ago. Jacques is a sedentary man who has never smoked. He has a history of gout, hypertension, and is “slowing down,” but generally feels well. At his last visit, Jacques had a blood pressure check and you renewed his medication. You recall a brief exchange about the negative results of his fecal immunochemical test (FIT) done 2 years earlier. You did not request another test.

As you are wrapping up her visit, Rachel challenges your omission of another FIT test for Jacques. After all, her husband was screened for colorectal cancer in the past. Was it now because he was “too old”? That put you on the spot—is there a simple way to explain the cascade of interventions that follow positive screening test results? What about cancer overdiagnosis? Not to mention competing risks of mortality .…

Deciding if an older patient would benefit from screening

Table 1 highlights many of the issues and steps that should be considered in decision making about screening in older patients.^1,4,6–10 Physicians will need to individualize their approaches to screening because of a range of life expectancies for older patients of a given age, the potential for harms from screening and uncertain benefits, and individual patient preferences and values.

Overscreening

Overscreening refers to the use of a screening test at ages younger or older than recommended or at a greater frequency than recommended (shorter rescreening interval). Overscreening also occurs when asymptomatic persons are tested in the absence of high-quality evidence to support the idea that such interventions improve health.¹¹ Overscreening in older patients is a problem, given that, past a certain age, patients could be more likely to experience harm from screening, while it usually takes many years for any mortality benefit from screening to accrue.^12,13

To avoid overscreening in the elderly, one consideration rises to the top: life expectancy. Two other considerations—namely patient values and preferences and downstream thinking about the possible outcomes of screening—are equally important but apply to people of all ages.

Life expectancy

For decades, the life expectancy of Canadians has been slowly increasing (Figure 1).¹⁴ According to Statistics Canada,⁹ the average Canadian man at age 75 has 10 years of life expectancy; however, this typically includes some years of life in failing health. Table 2 provides estimates of median life expectancy at 75, 80, and 85 years, as well as a range of life expectancies influenced by the severity of comorbid conditions.^7–9 Using this information can help to roughly estimate the life expectancy of your patient. The absolute risk of dying of breast, cervical, and colorectal cancer, and estimates of mortality reduction from screening over the remaining lifetime of persons with a life expectancy like your patient, is also provided. You could use these estimates to give you an order of magnitude of a possible benefit from screening. For some ages no reduction in cancer mortality can be expected from screening. For example, women at age 80 in the lowest quartile of life expectancy should expect no reduction in mortality from screening for cancer. Models to estimate life expectancy have been developed in Canada, the United States, and the United Kingdom, and in testing some have been found to be fairly accurate.^15,16 Such calculations can also be used to guide clinicians and might be of greater relevance to them than to their patients.

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Figure 1.

Change in life expectancy at birth in Canada since 1921

Reproduced from Statistics Canada with permission.¹⁴

Downstream thinking about the possible outcomes of screening

As Muir Gray has pointed out, “The harm from a screening programme starts immediately; the good takes longer to appear.”¹⁷ If the screening test results were positive, would your patient be willing to go down the path of diagnostic confirmation leading to treatment? In screening for colorectal cancer, a positive FIT result will raise the need for colonoscopy with biopsy, and a positive biopsy result will raise the issue of fitness to thrive following hemicolectomy. Regardless of comorbidities, any person so diagnosed is now a “cancer patient” with all this can imply. While the concept of watchful waiting (or active surveillance) is gaining traction for some types of cancer (eg, prostate), it is not possible to know whether a specific patient was overdiagnosed with a slow-growing tumour that was never destined to cause harm to him or her. Cancer overdiagnosis is understandably a cause of much uncertainty.¹⁸

In our case, it seems reasonable to ask Jacques what he would like his doctor to do. Would he have a colonoscopy in the event of a positive FIT result? In an asymptomatic patient, the purpose of screening is to treat any disease uncovered. If further testing, biopsy, or treatment would be declined, then no screening should be done in the first place (primum non nocere).

Shared decision making and patient values and preferences

When should one stop cancer screening? To the best of our knowledge, there is no systematic review examining the values and preferences of older patients around this question. That said, the concern expressed by Rachel and Jacques is not trivial given the rising incidence of cancer in older people. The big question is whether screening Jacques would add life to his years or years to his life.³ Treatment could certainly lower his quality of life; and many patients underestimate the harms of medical intervention,¹⁹ which might be greater with advancing age. Although Jacques could live to age 88, he could be told the Canadian Task Force on Preventive Health Care made a recommendation against screening for colon cancer after age 75²⁰; however, this is based on low-quality evidence and is a conditional (or weak) recommendation, which implies a need to consider individual patient situations including values and preferences.

One way to approach this case is through shared decision making with the patient or family members. Shared decision making is a structured process to incorporate values and preferences into screening and treatment decisions.²¹ Shared decision making is especially important for implementation of conditional or weak recommendations.²² When bringing up the idea that cancer screening might no longer be beneficial given a patient’s life expectancy, using direct language, such as “You might not live long enough to benefit from this test,” can be perceived as overly harsh. Instead, a statement such as the following might be better received: “This test is unlikely to help you live longer. Your other health issues should take priority.” Jacques should be informed that, in screening with a fecal occult blood test, the lag time to benefit has been estimated to be 10.3 years for an absolute reduction of 1 death prevented for 1000 persons screened.¹²

In screening for colorectal cancer after age 75, guidelines from the United Kingdom and the United States recommend that the decision to screen be an individual one.¹³ For some cancers, there is international agreement among guideline committees on the age to stop (eg, age 75 for breast cancer).²³ This guidance, as with the age to stop screening for colon cancer, is based on the absence of direct trial evidence to quantify the benefits and harms for women who outlive the recommended age for screening. In the absence of trial evidence, it is not easy to quantify the net benefit of preventive activities.

For patients who express a willingness to continue screening into advanced age, a values clarification exercise should be considered, once patients are informed of the uncertainty of benefit and possible harms. By values clarification we mean having a conversation about what matters most to our patients and their families in terms of health outcomes. This conversation can be helped by making time to work through a decision aid, such as the one on screening for breast cancer for women aged 75 to 84.²⁴ Research suggests the greatest potential for improvement in practice is in having such a conversation.²⁵

Framing the discussion on screening in older patients

Older adults might not consider life expectancy important in screening and might not welcome a discussion of their life expectancy when discussing screening.⁶ In our discussions with older adults, we should use phrases that are generally preferred by patients to explain cessation of routine cancer screening. Box 1 provides the phrases that were most and least preferred by older American adults.¹⁰

Physicians can provide their patients with decision aids as tools to supplement the discussion in the office.²⁶ Implementing patient decision aids during the clinical encounter can be challenging, as many people have difficulty understanding the concept of risk.^27–29 As we discussed in a recent article on organizing a practice for screening, there are compelling reasons to involve different members of the primary care team in screening activities.³⁰ For example, we could further develop the role of nursing.

And in the end …

Rachel and Jacques wonder about his continuing to be screened for colorectal cancer. Using Table 2,^7–9 you estimate Jacques to be at the 50th percentile for men about 80 years of age, giving him a good chance for more than 5 years of remaining life. You decide to invite Jacques for further discussion about the harms and benefits of continuing to be screened with the FIT. Further screening with the fecal occult blood test can minimally reduce the risk of death from colorectal cancer from about 18 to 17 per 1000 men at his age. He now understands the magnitude of a possible benefit from screening to be very small, with a 10-year lag time to benefit exceeding his estimated life expectancy. On the other hand, it is difficult to estimate the frequency of harms he might experience from screening. These harms include risks of dehydration from bowel preparation for colonoscopy, conscious sedation, bleeding or perforation from polyp removal, and the anesthesia of surgery. Based on this discussion, Jacques and Rachel decide to decline further screening.

There comes a time when many patients will have the good fortune to exceed the recommended age range for screening. For these people, we should consider an individualized shared decision making approach around the harms and benefits of screening.