European registry comparisons provide evidence of shared risk factors for renal, colon and gallbladder cancer development.

In order to assess links between renal cell cancer (RCCs) and transitional cell cancers (TCCs) of the kidney and cancer development in other organs of the abdominal cavity, incidence data from the Cancer Incidence in Five Continents (Vol VII) were compared between various cancer registries in Europe. Significant correlations which persisted on partial analysis were observed between RCCs and carcinomas of the colon and gallbladder, as well as between the latter themselves. Kidney TCCs, in contrast, were associated with tumours of the urinary bladder. In addition, significant correlations between hepatocellular, but not cholangiocellular carcinomas, and gallbladder and colon cancers were observed. Data for pancreas and gallbladder neoplasms also correlated. Prostate cancer incidences, while positively linked to RCCs, negatively correlated with gallbladder rates. The results point to shared risk factors for RCCs and adenocarcinomas in a number of organs, suggesting a role for humoral agents. The present findings also underline the necessity of distinguishing between tumour types within organs in epidemiological investigations of causal influences.