Abstract
“All screening programmes do harm; some do good as well, and of these, some do more good than harm at reasonable cost”
This simple, but profound, statement summarizes the main issues around population screening. 1 Screening involves undertaking health examinations or tests to identify those with or who are at risk of developing a serious disease. Treatment or prevention regimes should be made available to all who participate in these programs.
The principles of modern screening were stated in a World Health Organization (WHO) review 6 decades ago and include the following. 2 Screening should be for an important health problem, a reliable test must be available, and facilities for diagnosis and treatment should be available for patients with recognized diseases. The screening should be cost-effective. Importantly, the cost of case finding (including diagnosis and treatment of patients diagnosed) should be economically in balance with total expenditure on health for the target population. The categories of screening described by WHO Europe include case-finding, opportunistic screening, population-level screening programs and targeted screening. 3 As with all public health programs and health care, the principle of “do no harm” must be maintained or, more appropriately, a balance achieved between benefit and possible risk.
Case detection has been widely used in public health to prevent the spread of disease, and programs to eliminate smallpox and tuberculosis are good examples. Changing disease prevalence and advances in technology require the continuing reassessment of screening programs. When tuberculosis (TB) was more prevalent, mass chest radiology enabled the treatment of individuals and the prevention of the spread to larger populations. Better laboratory techniques and declining prevalence mean that this is no longer used. As technology develops, it can be overused for trivial issues, if risks are ignored. As a small child, I (CWB) remember being taken to a large shoe store in the city; I stood with my foot inserted into a machine, and my mother and the salesperson saw an outline of my foot and assessed whether my new shoes fitted. Between 1920 and 1950, X-ray fluoroscopy was used in the United States, Europe and other regions to help fit shoes accurately. Its use resulted in cases of radiation damage, and it was phased out in the early 1950s. 4 Aside from being a trivial use of advanced technology, this violated the ethical principle of doing no harm.
Modern public health programs are targeted at specific age groups and/or risk groups but apply the basic principles of public health of doing good, no or minimal harm and promoting equity. Currently, many countries offer screening programs for bowel cancer, breast cancer, cervical cancer, newborn diseases (blood spot tests) and newborn hearing. If the incidence of disease declines and the screening program is no longer benefit/cost positive, there should be a mechanism for its discontinuation. Just as chest radiology for TB is no longer needed, the need for all other screening programs should be periodically evaluated. It is likely that cervical cancer screening will become redundant in the next decade due to the benefits of vaccination.5,6
Until the 20th century, the practice of medicine and public health relied almost entirely on taking histories and physical examination or the use of monitoring and surveys at a population level. In the past century health technology expanded with benefits (and costs) to patients and communities. But this advance created the problem of how to manage unexpected abnormal results. While some may be important, many extraneous results are for trivial or stable conditions. This is not a new problem: By 1932, the most common problem cited by doctors tests ordered in hospitals as a matter of course, without apparent relevance to the condition for which the patient was admitted or understanding of the test’s meaning or limitations was the large number and unintelligent use of laboratory.
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The development of the automated biochemical, hematology and microbiological techniques since the 1950s has expanded capacity and reduced costs. 8 The technology is now available for multiple complex screening programs for communities and the individual.
From a public health perspective, a screening program should bring benefit to the individual and to the population. The availability of new technology, including more recently magnetic resonance imaging (MRI), has enabled its application to larger populations. This has also led to a demand for individual testing to prolong healthy life.
Advertisements such as this appear regularly online and in the press: The Whole Body MRI package offers a fast, radiation-free way to screen your entire body, making it a powerful diagnostic option for those seeking a thorough yet non-invasive check-up.
Davenport 2026 offered a warning about the risks of screening with MRI and included a suggested consent for which in part reads: No medical guideline recommends that you undergo this test. There is a 3 in 10 chance we find something that creates uncertainty for you, which could result in anxiety, sleeplessness, financial strain, life disruption, more imaging, invasive procedures, or possibly surgery. Although cancer will be identified in 1 or 2 out of 100 people, finding cancer with this test is unlikely to help you because most types will be low risk or already advanced. There are no studies showing that undergoing this test will improve the quality or length of your life.
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This is a good summary of potential medical risks. The use of MRI is a considerable advance in medical technology, but it must be integrated into health systems with care. From a public health perspective, opportunity costs must be considered. All communities have limits to the number of national resources that can be devoted to health, both private and public. Personal screening, if it develops on a large scale, will divert scarce resources, including health personal, away from more beneficial public health activities. Magnetic resonance imaging can detect very small lesions of no clinical consequence but will lead to unnecessary investigations, which can risk further complications. Any use of medical resources also comes with an environmental cost. 10
In our public health education and continuing education programs, students need to be reminded of the important principles underlying screening so that the whole population can gain a benefit to their health.
In this issue of the APJPH, we provide a wide range of public health articles, ranging from a review on remote support of breastfeeding to the relationship between climate and cardiac disease.
The Asia Pacific Academic Consortium for Public Health (APACPH) 57th Conference will be held from October 20 to 23, 2026, in Tainan, Taiwan, at National Cheng Kung University (NCKU). The conference theme is “Leveraging Healthcare Technology and Innovation for Public Health Advancement.” The APJPH editorial team will be present and can assist with advice on publication.