Abstract
The different criteria to be taken into consideration when carrying out presymptomatic screening of neoplastic diseases are given. Screening is an operation of secondary prevention and can be divided into: 1) mass screening 2) selective (or aimed) screening 3) multifascia screening (check up). The Author gives the fors and againsts of the above types of screening and concludes that they can lead to: 1) only a prolungation of the lead time 2) a more favourable life expectation 3) a normal life expectation with death due to the neoplasm 4) death for natural causes and not for the tumour 5) early death (iatrogenic). The general criteria laid down by the W.H.O. on the suitability of submitting a population to screening are: a) the pathology to be investigated must be an important problem both for health and socially b) a diagnostic protocol must be available for subjects who have a positive test result, as well as an effective treatment protocol for the diagnosed cases c) the investigated pathology must be characterised by a recognisable stage, latent or with early symptoms d) screening methods must be easy to carry out with no risks involved e) the screening must be acceptable for the invited population f) the natural history of the neoplasm must be sufficiently well-known g) the parameters of normality, allowing the positive patients to be distinguished from the negative ones, must be very clear h) assessment of the cost/benefit ratio i) the activity of early diagnosis must be a continuing and not an irregular service, on the basis of established protocols I) the availability of economic, staff and organisational resources must be guaranteed. In any case, the Author proposes that the screening programme be checked in terms of sensitivity (capacity to select the truly ill people), specificity (capacity to select the healthy ones) and predictive value (% value of test reliability).
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