The social aspects of cancer control and demographic transition
Date: Thursday 1 November 13.30–15.00
Two phenomena, one of which relates to the area of human reproduction and the other to the frequency, distribution and control of disease in a population have emerged in the previous century and continue to develop intensively. Both these phenomena are directly related to the changes that are occurring in the incidence and prevalence of malignant tumours, as well as to mortality from them and to the opportunities for cancer control. The first of these phenomena has been denominated as demographic, and the second as an epidemiological transition.
The commonly accepted definition of a demographic transition is currently applied to designate a sustainable change in the type of population reproduction, when an initial and abrupt acceleration of population growth is replaced by its rapid deceleration with a subsequent stabilization of a population and a sharp change in its age structure. Demographic transition develops in a brief historical space of time and has the character of a global process. Population aging and disequilibrium between the younger and older generations are the most important consequences of the demographic transition, and must inevitably influence the strategy and implementation of national cancer control programmes.
As life expectancy increases, so does the certainty that people will become more and more prone to diseases that are more common among older age groups, i.e. noncommunicable diseases and cancer in particular, rather than being affected by epidemics of infectious diseases. This situation is known as the epidemiological transition and reflects spectacular shifts in the pattern and causes of death and morbidity that have taken place in the vast majority of countries over the previous century. Epidemiological transition results in accession by poor countries to the problems of the rich, and leads to the `double burden' of disease in countries whose economies are undergoing transition, because of the still continuing heavy burden of endemic infectious diseases.
The majority of developing countries, with their fluctuating economies and low level of population income, are entering the final stages, both of the demographic and the epidemiological transition, a period when increasing demands on the systems of social protection and public health are inevitable. According to recent global estimates the number of new cancer cases in the year 2006 exceeded 12 million, and the number of deaths from cancer reached almost 7 million. The annual growth rate of global cancer incidence during the last 3035 years was higher than the global population growth rate.
Analysis of data available from several reliable population-based and personalized cancer registries in different regions of the world confirms the conclusion that cancer is mainly the fate of people belonging to the older age groups. Given the levels of exposure to specific carcinogens and genetic predisposition factors, the incidence of cancer should be considered an exponential function of age.
The unfeasibility of attempts to change, in the foreseeable future, the rate and trend of demographic transition and population ageing, in particular, is obvious. It would therefore be more rational to envisage their probable consequences and to adapt the limited resources of national health and social support services to the needs of cancer control, which will significantly increase in the very near future.