Cancer in developing countries.

The developing countries are represented by incidence and mortality datasets from 16 populations. Trends are studied using age specific data from six cancer registries (three in Asia, three in Latin America) and national mortality datasets from Central and South America (three), the Caribbean (two), Asia (two) and Mauritius. In Africa, three cancer registries (in Nigeria, Uganda and Zimbabwe) provide time series of 15 years or more. Systematic examination of time trends is confined to five major sites (stomach, lung, breast, cervix uteri and colon-rectum), with a comment on observed trends in the other important cancers of developing countries (mouth/pharynx, oesophagus and liver). Although uniformity is not to be expected in such diverse material, some overall patterns emerge. Stomach cancer, as in the developed world, appears to be declining in importance. Lung cancer rates are rising, although in males, the increases are most marked in the elderly, with more recent birth cohorts in several populations showing a decline in risk. Breast cancer incidence and mortality rates are rising in most populations, with changes usually more marked in younger women. Conversely, cervix cancer, at present the most common cancer of women in developing countries, shows declines in incidence and mortality in the majority of populations studied, although Africa is clearly an exception. Cancer of the large bowel is becoming more frequent, although there are exceptions (eg Bombay, Mauritius and Trinidad). In the highest risk population (Uruguay), mortality seems to have peaked around 1965 and has since declined.