A geographic correlation study of the incidence of pancreatic and other cancers in whites

Ecologic analyses of cancer incidence rates may be helpful to formulate hypotheses on risk factors and mechanisms of poorly known neoplasms, such as pancreatic cancer. We calculated sex-specific pair-wise and partial (after adjustment for lung cancer incidence) correlations between the incidence of pancreatic cancer and that of 23 other cancers in two international sets of cancer incidence data: the recorded or estimated incidence for 2000 in 38 European countries and the recorded incidence in Whites for 1993-1997 in 35 cancer registries from North America and Oceania. In both sexes and datasets, a strong, highly significant correlation was present between the incidence of pancreatic cancer and that of lung and kidney cancer. For the latter, correlation coefficients in the European data were 0.71 in men and 0.74 in women (both p<0.0001); in the cancer registry data they were 0.57 (p=0.0004) in men and 0.45 (p=0.007) in women. The results on kidney cancer were not modified by adjustment for the correlation with lung cancer, were confirmed by the application of spatial regression models and, with the exception of men in the cancer registry data, were confirmed in sensitivity analyses restricted to the populations with data of best quality. Weaker, less consistent correlations were found for colorectal, endometrial, ovarian and bladder cancers. Tobacco smoking is a plausible explanation of the association between pancreatic and lung cancer; the association with kidney cancer likely reflects additional common etiologic and pathogenetic factors of the two neoplasms.