Variation in international cancer mortality: factor and cluster analysis.

Mortality rates for cancers of 13 sites in 34 countries were analysed using two data reduction techniques, factor and cluster analysis. Factor analysis identified two independent underlying factors which appear to influence cancer mortality patterns. The first factor, which appears to be related to affluence, may represent the combined effects of high fat diets and cigarette smoking common in developed countries. The second factor may reflect the common consumption of beverages of a high tannin content such as tea, red wine and 'mate' as well as the smoking or chewing of black tobacco. Two factor scores were computed for each country, and the countries were then ranked according to their scores on each factor. Cluster analysis aggregated countries into seven distinct groups using these factor scores as the clustering criteria. Each of the groups thus defined displays a distinctive profile of site-specific cancer mortality rates. This methodology shows promise as a means of summarizing large sets of data on morbidity and mortality from a variety of cancers (and possibly other chronic diseases as well) in diverse populations.