Background: Previously we identified the age at half-total incidence (Age 1/2) for a variety of tumors. In this paper, we compare the Age 1/2 with the age- standardized incidence rate (ASR) in populations that differ a) genetically and environmentally and b) genetically but not environmentally.
Materials and methods: From 1990-era data, we calculated 95% confidence limits about mean values for Age 1/2 and ASR for cancers of the stomach, colon, rectum, lung, female breast, corpus uterus, ovary, testis and prostate.
Results: In populations that differed genetically and environmentally as well as those that differed genetically but not environmentally, we observed large variations in ASR, with little or no variation in Age 1/2.
Conclusion: The determinants of ASR are distinct from the determinants of Age 1/2 and likely to be genes that can vary between tissues of tumor origin but are common to all people.