title: Collecting duct carcinomas represent a unique tumor entity based on genetic alterations.
abstract: Collecting duct carcinoma (CDC) is a rare renal neoplasm that is associated with poor prognosis due to its highly aggressive course and limited response to immuno- or chemotherapy. Histologically, CDC is defined as a subtype of renal cell carcinomas, but in some cases, it is difficult to differentiate from urothelial carcinomas (UC). Therefore the aim of this study was to determine genetic alterations of CDC in comparison to that of urothelial carcinomas of the upper urinary tract (UUT-UC) to clarify the histological origin of this rare tumor entity. Twenty-nine CDC samples were obtained from seven different German centers and compared with twenty-six urothelial carcinomas of the upper urinary tract. Comparative genomic hybridization (CGH) was used to investigate the genetic composition of patients' tumors and allowed the detection of losses and gains of DNA copy numbers throughout the entire genome. The clinical data were correlated with CGH results. CGH analysis of CDC revealed DNA aberrations in many chromosomes. DNA losses were more frequently observed than gains, while high-level amplifications were not detected. The mean frequency of CDC chromosomal aberrations (4.9/case) was slightly lower than that in UUT-UC (5.4/case). Recurrent CDC DNA losses occurred at 8p (n=9/29), 16p (9/29), 1p (n=7/29) and 9p (n=7/29), and gains occurred in 13q (n=9/29). In contrast to CDC, the most frequently detected UUT-UC DNA aberration was a loss at 9q (n=13/26). DNA losses at 9q, 13q and 8q as well as gains at 8p showed significant variations in UUT-UC compared to CDC. There was no correlation between the patients' clinical course and the presence or absence of these recurrent genetic alterations. CDCs are characterized by a different genetic pattern compared to UUT-UC. Regarding the published data on renal cell carcinoma, we conclude that CDC appears to be a unique entity among kidney carcinomas.
authors.affiliation: Department of Urology, University of the Saarland, Homburg/Saar, Germany ; Urological Group Practice & Clinic Derouet/Pönicke/Becker, Boxberg Center, Neunkirchen, Germany ; for the German Network of Renal Cell Tumors, Jena, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Becker
authors.forename: Kerstin
authors.initials: K
authors.lastname: Junker
authors.forename: Martin
authors.initials: M
authors.lastname: Parr
authors.forename: Arndt
authors.initials: A
authors.lastname: Hartmann
authors.forename: Susanne
authors.initials: S
authors.lastname: Füssel
authors.forename: Marieta
authors.initials: M
authors.lastname: Toma
authors.forename: Rainer
authors.initials: R
authors.lastname: Grobholz
authors.forename: Thomas
authors.initials: T
authors.lastname: Pflugmann
authors.forename: Bernd
authors.initials: B
authors.lastname: Wullich
authors.forename: Arne
authors.initials: A
authors.lastname: Strauss
authors.forename: Carl Ludwig
authors.initials: CL
authors.lastname: Behnes
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Otto
authors.forename: Michael
authors.initials: M
authors.lastname: Stöckle
authors.forename: Volker
authors.initials: V
authors.lastname: Jung
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000235:genetics* / Q000473:pathology; D002869:Chromosome Aberrations; D002877:Chromosomes, Human / Q000235:genetics*; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged