Kim H, et al. - The purpose of this study was to detect and characterize the tumors of each clonal origin, by performing a human androgen receptor gene (HUMARA) assay to compare the X-chromosome inactivation patterns of multiple tumors. Findings demonstrated that 40.8% patients were heterozygous for HUMARA. It was determined that 2 separate tumors could appear to be synchronous primary tumors, despite having similar histopathological characteristics. Additionally, multifocal tumors could be of different origins regardless of being closely located to each other.