Dreger NM, Degener S, Roth S, et al. - Researchers assessed how the outcomes, as well as the health-related quality of life of patients with retroperitoneal fibrosis (RPF) receiving tamoxifen (TMX), could be influenced by CYP2D6 polymorphisms. By employing multiplex polymerase chain reaction, they evaluated CYP2D6 genotyping and phenotype prediction of all patients managed with TMX between 02/2007 and 01/2018. Categorization of groups by phenotype was done: extensive (EM) vs poor and intermediate (PM + IM) vs ultrarapid metabolizer (UM). Regression of fibrosis for EM and PM + IM in 69% and 62.5% of cases and a progression for UM in 100% was revealed on magnetic resonance imaging. A significant reduction in glucose utilization of RPF was revealed, on positron emission tomography-computed tomography, for EM and PM + IM. The lowest success rate was displayed by UM, as opposed to expectations. Experts inferred the possible usefulness of genotyping of RPF-patients in the sense of a tailored-therapy.