When patients come to see me, they normally have a problem that physicians call the “chief complaint.” In investigating and treating that complaint, I must obtain informed consent—communicating the risks and benefits of any proposed tests, procedures, treatments, and alternative treatments to ensure that my patient makes an informed decision about how to proceed. Gone are the days that a physician could dictate care without such consent.
In contrast, when I recommend a screening test, I’m not treating a known problem. Rather, I’m seeking out a healthy person and proposing a medical procedure to discover unsuspected disease before the patient develops symptoms. To be effective, the screening test must be sensitive enough to detect the presence of the disease and specific enough to identify people who don’t have it.
There must also be effective treatments, so that catching the disease early, before it becomes clinically apparent, leads to better outcomes. Thus, screening is not directed at individuals with specific complaints but rather at large populations in an attempt to lessen their mortality risk from specific diseases.
Screening differs from traditional treatment in another important way. Unlike patients with specific problems, who must give informed consent to treatment, healthy patients are often pressured to undergo screening and are rarely provided with the knowledge needed to make an informed decision.
Many medical organizations and patient-advocacy groups oversell the benefits of screening but almost never mention that screening tests, like other medical procedures, have potential harms. One-third of men undergoing prostate-specific antigen (PSA) screening for prostate cancer, for example, don’t recall being told that the test was being performed, let alone hearing about the risks and benefits.
Yet Americans have enthusiastically embraced screening. The United States performs screening, particularly for cancer, more commonly than other advanced countries. We spend tens of billions annually on cancer screening, including $8 billion for breast cancer, over $6 billion for cervical cancer, and $3 billion for prostate cancer. For some cancers, screening expenditures nearly equal the amount spent on treatment.
Why do we encourage large numbers of healthy people to undergo testing that may reveal some future problem, without informing them of the efficacy of these tests and their possible harms, while insisting that people who actually need medical intervention give informed consent? The reasons are more political than scientific. Patient-advocacy groups attract donations, gain prestige, and accumulate power by pushing screening for particular diseases.
Physician-specialty groups promote screening in their areas of expertise. Most important, politicians of both parties garner support by funding screening programs for important constituent groups. Yet the effectiveness of screening is overrated: many screening programs mislead the public, waste scarce medical resources, and harm the people they are supposed to help.
The Stanford Prevention Research Center, in a comprehensive review of 39 screening tests for 19 diseases, found that reductions in death due to screening are rare. Nevertheless, patients routinely undergo overly intensive, low-value tests. About half of women who had a hysterectomy and no longer have a cervix, for example, are still getting PAP tests for cervical cancer screening.
Despite the absence of evidence supporting screening in these older populations, cervical and breast cancer screenings are performed in 38 percent and 50 percent, respectively, of women over 80; and more than 50 percent of men over 75 report that their physicians continue to recommend PSA screening. It is nearly certain that these older men and women will die of some cause other than occult breast, cervical, or prostate cancer.
One study found that significant numbers of Medicare patients with a known advanced cancer and a short life expectancy were still being screened for other cancers.
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