Cross-country comparisons of colon and rectal cancer mortality suggest theexistence of differences in risk factors in eastern and western Europe

A comparison of relative mortality rates from colon and rectal cancers in W orld Health Organization data for various countries in Europe was undertake n to determine whether the two sites demonstrate a direct link. A significa nt correlation between figures for colon and rectal cancers was found throu ghout Europe but limited to males and only at the p < 0.05 level. Cluster a nalysis revealed marked differences between countries of the former west an d east European blocks, the latter having much higher values for rectal can cers, Separation of countries on this basis gave rise to significant correl ation between the two sites for both sexes (p < 0.05 and p < 0.001, respect ively, for western and eastern males; and p < 0.05 and p < 0.001 for female s). In order to assess the possible contribution of factors associated with squamous cell cancers (SCCs), data for buccal and cervical cancers, both m ore prevalent in eastern than in western Europe, were also compared. Wherea s a significant correlation was evident between female rectal and cervical cancers overall and in the western countries (p < 0.05) this was not the ca se for the eastern countries. The results suggest that the observed excess of rectal cancer mortality in eastern European countries may not be simply due to factors contributing to SCCs, but that country level comparisons of individual harmful and beneficial, influences, alone and in combination, mi ght allow the underlying reasons to be explained. (C) 1999 Lippincott Willi ams & Wilkins.