When Cochrane meets Machiavelli: the science and politics of population cancer screening in Hong Kong (#131)
Population cancer screening is a classical “motherhood-and-apple-pie” issue. It is almost always accepted by patients, doctors and the general public as being inherently desirable. Like all diagnostics in medicine however, the basic epidemiologic characteristics and economic consequences of any test should be subjected to careful scrutiny before widespread promulgation, especially when targeted at well populations.
Breast cancer is the commonest female malignancy in much of the developed world, and fast becoming such in the rapidly developing populations of emerging economies. Unlike other common cancers such as cervical or colorectal disease, there is still no readily identifiable obligate precursor state (rather than only a risk factor) that is amenable to early curative intervention. This immediately reduces the preventive potential of any screening test to one of early recognition as opposed to preventing the occurrence of malignancy altogether. For Hong Kong women who sustain one of the highest incidence in Asia and where mammography screening remains haphazard, if one were to allocate additional resources to breast cancer care in general, in descending order, the optimal dispersion would be the following: a 25% reduction in waiting time for postoperative radiotherapy (in US dollars: $5000 per QALY); enhanced, home-based palliative care ($7105 per QALY); adjuvant, sequential endocrine therapy ($17,963 per QALY); targeted immunotherapy ($62,092 per QALY); and mass mammography screening of women aged 40 to 69 years ($72,576 per QALY). Looking across cancer types, full liquid Pap screening coverage every four years followed by colonoscopy screening every ten years would avert the most malignancy-related DALYs before mammography should be introduced.
Beyond the numerical evidence, breast disease carries special meaning at the psychological, sociological and political levels. These issues often matter more to public perception, thus politics and policymaking. Vested interests from purveyors of mammographic equipment to service providers converge with the motivation to “do something” of well-intentioned advocates. Such alliances often render any rational and honest discussion in the public sphere difficult, resulting in uninformed decision-making by individual well women and inappropriate policy responses at large. The very different experiences with mammography screening in Singapore and Hong Kong, albeit with similar underlying epidemiology, are an interesting counterpoint. In parallel, questions about screening as a preventive measure are increasingly aired publicly in the US and Europe.