Associations Between Tumor Types in a Large-Scale Carcinogenesis Study of CF-1 Mice2

Abstract

Crude associations between tumor types found at necropsy in a multigenerational carcinogenesis experiment involving over 4000 CF-1 mice were demonstrated, in certain cases, to arise spuriously from the grouping of animals by treatment and/or from similarities in the age-specific tumor prevalence curves. When adjusted for these two factors, statistically significant associations nevertheless remained: Lymphomas were negatively related to hepatomas, lung adenomas, and mammary and ovarian tumors, and positively associated with bone tumors. With the possible exception of the relationship between hepatomas and lymphomas, negative associations are thought to be an artifact due to a competing-risks phenomenon. The lone positive relationship could reflect a common viral etiology