Global cancer burden

The existence of differing patterns of cancer occurrence throughout the world has been known for many years, as perusal of the fascinating monograph published in 1915 by Hoffman, the actuary to the Prudential Assurance Company reveals. It was not, however, until 1984 that estimates (based on the year 1975) were made, not only of the global cancer burden but also for each of the 24 demographic regions recognized by the United Nations (UNO, 1986). This was later updated by Parkin et al. (1988), who estimated the global total of new cancers to be 6.35 million. This number was almost exactly divided between the sexes and between developed and developing countries, although two-thirds of the world population dwells in the latter.

The ‘top ten’ cancers are given in Table 22.1. Unfortunately, these figures are essentially estimates, since they are not uniformly collected, being derived from various sources. The latter include incidence figures from cancer registries, and incidence estimates extrapolated from mortality. For large areas of the world, numbers are based on relative frequency data, mostly obtained from the monograph Cancer Occurrence in Developing Countries (Parkin, 1986). Regrettably, the calculation of age-specific and age-standardized incidence rates, which provide a measure of the difference in risk between populations was not possible. The methods used, notably for the developing countries, are discussed in the original papers.