Studies on Screening for a Cancer

Abstract

An epidemiologist’s concern for the health of the cared-for community/population actually is not limited to community-level preventive medicine, without regard for whatever may be going on in the clinical segment of healthcare at large. (S)he understands that the people’s health – public health in this meaning of the term – is much influenced by the aggregate of clinical healthcare (preventive, therapeutic, rehabilitative) in the community – mostly for the better but, also, for the worse. And as a consequence, (s)he is concerned to optimize people’s use of clinical care by means of community-level health education aimed at prevention of both under- and overuse of clinical care.

One line of this education has to do with screening for risk factors for illnesses (e.g., the BRCA 1 & 2 mutations with a view to detection of high risk for breast cancer), preparatory to decision about preventive interventions (e.g., by tamoxifen use) and/or screening for the illness at issue (breast cancer in this example) – that is, pursuit of early, latent-stage diagnosis (rule-in) about the illness with a view to enhanced curability by early treatment.

Screening is directed to individuals one at a time, and it thus is clinical healthcare, by definition. Screening for a risk factor is preventive care, while screening for an illness is therapeutic – therapy-oriented – care (when opportunity for successful prevention already is passé). The yield of screening is information, and this in itself has no effect on the person’s course of health. It thus is not an intervention.

This chapter addresses, in the main, the epidemiologic researchers’ misunderstandings in regard to these orientational concepts and the consequent serious misunderstandings about research on the intended consequences of screening, for a cancer in particular. Epidemiologists should come to understand that the knowledge-base, just as practice, of screening is a clinical matter.