Jeong CW, et al. - Researchers sought to present a comprehensive description of this dataset and investigate possible biases due to missing data. In the USA, the Surveillance, Epidemiology, and End Results (SEER) is a population-based epidemiologic registry. They distinguished a total of 316,724 individuals in the entire cohort and 257,060 men with clinically localized prostate cancer (PCa) (T1-2N0M0). They assessed the degree of missing data for each variable. They correlated two versions of the data: one that excluded cases with missing data and one dataset generated applying multiple imputations to examine possible bias due to missing data for cancer characterization. Moreover, while the SEER Prostate with the WW dataset allows a new approach to defining treatment trends for men with PCa, including the use of AS/WW, the amount of missing data should not be overlooked.