Survival data relative risk

Mortality data are frequently used in cohort studies as opposed to incidence data because of the relative ease of obtaining information on deaths. In particular, the advent of the National Death Index has made mortality data more readily available. While all states maintain registries of incident cancer cases, many of the registries are relatively new and data quality can vary from state to state. Investigators conducting follow-up studies are required to comply with each state s requirements for use of the data. For cancers such as pancreatic cancer where survival is poor, mortality data is an excellent surrogate for the risk of the disease. For other cancers where the survival is much better, such as testicular cancer, mortality is a poor estimator of incidence. Table 15.5 describes the 5-year survival for several selected cancer sites for the period 1996-2004. As evident from the table, there is a considerable difference in survival rates for cancer of different sites. The 5-year survival rate for pancreatic cancer was only 5.1% compared to a survival rate of 98.9% for prostate cancer (SEER 2008). 

Toxicity studies in rodents and environmental species indicate that chronic exposure to relatively low concentrations of particularly SCCPs and MCCPs adversely affects survival and development. Much of the toxicity data on the CPs is dated, and suitable analytical methods were not available to well characterize internal doses or exposure concentrations. The development of improved analytical methods and monitoring of these heterogeneous compounds is challenging, but has certainly improved over recent years. This is essential in distinguishing the possible effects of impurities in technical CP mixtures and will aid in the accurate comparison of exposure data with hazard information based on internal dose to establish better risk characterization. 

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