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Cancer is an important, challenging and increasing health problem. It exhibits a
striking geographic variation related to differences in the age structure of
populations, as well as environmental factors. The cancer incidence reaches its
maximum in developed countries in view of aging of the population, urbanization
and adoption of industrialized life style. In the following text both the
magnitude and pattern of cancer will be presented in developed, as well as
developing countries. The USA and Europe are selected as a model for the
developed countries, whereas, the cancer problem in the Arab countries and Egypt
is discussed as an example of developing countries.
THE GLOBAL CANCER PROBLEM
Incidence Profile
The worlds population was only 2.6 billion in 1950 , but in the year 2000 it
will reach 6.1 billion, and in 2025 it is estimated to reach 7.6 billion. About
75% of world population is located in developing countries. The population
growth rate will slow from the current 1.5% to below one percent by 2025.
Worldwide, the population of those aged 65 and older will increase more than
twice as fast as the total population between 1996 and 2020. The growth rate of
the elderly age group in less developed countries will be double the rate in
developed countries. The current global cancer burden is about 9 million new
cases per year and will increase in the future (Magrath, 1993). More than 50% of
the global cancer burden affects developing countries. The estimated cancer
incidence in developing countries is about 100 per 100,000 population, whereas
in developed countries it is 3 to 4 times higher.
Parkin and associates (1993) assessed the five ranking sites of cancer in the
year 1985 for males and females for the world as a whole (Fig. 1). Combining
both sexes together, lung cancer emerged as the most common type of cancer
globally, contributing 11.6%, followed by stomach (9.9%), breast (9.4%),
colon/rectum (8.9%) and uterine cervix (5.7%). It is difficult to predict what
the future burden will be, but probably there will be a rise in lung, prostate
and breast cancers and a decline in gastric cancer. The global incidence of lung
cancer is increasing by about 0.5% per year.
The WHO (1997) also estimated the global incidence of the major cancers in men
and women in 1996 (Table 1). Lung cancer held the leading position as the most
common cancer in men, followed by stomach, colon/rectum, prostate, mouth/pharynx
and liver. On the other hand, cancer of the breast represented the leading
cancer in women followed by cervix, colon-rectum, stomach, lung and
mouth/pharynx.
Cancer as a global cause of death ranked third in developing countries after
infectious parasitic diseases and diseases of the circulatory system. whereas,
it ranked second in developed countries after diseases of the circulatory system
(WHO, 1997).
In developing countries, as in sub-Saharan Africa the most frequently diagnosed
cancers in men include non-Hodgkin’s lymphoma, Kaposi sarcoma and cancer of the
liver, stomach, esophagus, and penis, whereas, in women the age–adjusted
incidence of cancer of the uterine cervix exceeds that of the breast. |
