Cancer is and has been relatively neglected in developing countries. This stems from the fact that cancer is a particularly complex health problem which consumes extensive human and financial resources. This acts as a disincentive to national policy makers in resource-poor countries and international agencies to address it ; available resources often remain insufficient to deal with even the most basic public health issues, such as the provision of a clean water supply, an adequate diet, and provisions for the control of major infections. Major strides have been made in human development, however, and while some severely impoverished nations have still to overcome these most pressing problems, many developing countries are beginning to divert more resources to the increasing problem of non-communicable diseases (projected to increase to 73% of the global burden of disease in 2020, from 43% in 1998). Non-communicable diseases, the third largest of which is cancer, account for more than 87% of the disease burden in high income countries. Their prevalence is increasing rapidly in low and middle income countries and they have recently been given a higher priority in World Health Organization programs. Nonetheless, available resources, particularly for cancer, within the developing countries remain grossly inadequate to deal with this burgeoning problem.- more than 5 billion people (85% of the world's population) are in developing countries which account for only 20% of the global gross national product (Figure 1).

FIGURE 1

Comparison of population and income in various groups of countries according to World Bank designations (data from World Bank, 1998)

Cancer will become an increasingly important cause of premature mortality in the developing countries as their populations expand and age, and as tobacco consumption increases and diets are westernized. Already, approximately 60% of global cancer occurs in developing countries (Figure 2) and unless the increasing incidence rate of cancer can be slowed - probably 10 million new cases per year at present - it is likely to double by 2020, most of this increase occurring in developing countries.

FIGURE 2

Percentage of premature deaths (1998) from infection/parasitic diseases and cancer in WHO regions and income groups

Cancer is steadily becoming a more important cause of premature mortality than infectious disease in developing countries - cancer deaths already exceed infectious deaths in China and a number of middle income countries (Figure 3).

FIGURE 3

Actual deaths from cancer (1998) in WHO regions and income groups (thousands)

Effective control of cancer will require major commitments to the training of health care professionals and the provision of adequate facilities for treatment, as well as public education programs and an efficient private sector producing relevant drugs and medical equipment. Further, a national policy will need to be established in which priorities are based on the pattern of cancer within a specific country. Cancer is not a single disease, but rather a group of hundreds of diseases, each arising in a different cell type and requiring different approaches to prevention and/or therapy. Each cancer has a different cause and different set of predisposing factors, some of which may be relevant to several cancers, e.g., tobacco.

Prevention may be the best means of control for some cancers, e.g., lung cancer, early detection for others e.g. oral cancer, and treatment for others e.g. hematologic and pediatric cancers, but even the primary treatment modalities, surgery, radiation and chemotherapy, differ with respect to their effectiveness in different cancers, and are generally much more effective when cancer is detected at an early stage. Recent increases in 5 year survival rates in affluent countries are likely to be primarily due to earlier detection achieved through improved public and professional education. The poor results in preventing or treating cancer in resource poor countries, however, tend to dissuade governments from spending money on cancer control, thus creating a vicious cycle which can be broken only by improving results. Ultimately, the effective control of cancer, that is, the reduction in the morbidity (suffering) and mortality (death) from cancer, can only be accomplished through research, which provides both a foundation on which to base control strategies, and a means to evaluate the effectiveness of such strategies. There can be no progress without research.