Combination of Urine Cytology and FGFR3 Mutation for the Diagnosis of Urothelial Carcinoma
Ling Gao, Poluru L Reddy, Loren Joseph, Tatjana Antic, Jeffrey Mueller, Ghazal Khan, Minerva Torres, Richard DeMay, Ward Reeves. University of Chicago, Chicago
Background: There were 70,980 new cases of urinary bladder carcinoma (BC) with 14,330 deaths in the United States in 2011. Urothelial carcinoma (UC) is the most common type, it primarily presents as a nonmuscle-invasive tumor (NMI). 80% of UC patients suffer recurrence within 2 years of initial treatment. Urine cytology is the main screening and follow-up tool, but sensitivity (66.6%) is not high for low-grade (LG) tumors. FGFR3 is a tyrosine kinase important in differentiation and proliferation. 80% of patients with NMI tumor have FGFR3 mutations, this is associated with improved prognosis. 17% of HGUCs have FGFR3 mutations, the presence of mutation does NOT impact prognosis. A simple FGFR3 mutation assay of bladder washing could increase diagnostic sensitivity when combined with urine cytology. This study demonstrates feasibility of such an assy in correlation with urine cytology and surgical histology of the bladder.
Design: Fifteen fresh bladder washings from 2011 were spun-down after cytology slide preparation, the pellets stored at -200C. Only specimens with a high urothelial cellularity were tested. All diagnoses were reviewed by two cytopathologists. DNAs were extracted from the cell pellets, Exons 10 and 15 were PCR amplified, then sequenced with BigDye Terminator Cycle Sequencing Kit (v1.1). The capillary gel electrophoresis was on an ABI PRISM 3100; mutations were analyzed with Mutation Surveyor Software (Soft Genetics).
Results: None of the specimens with only reactive (n=6) or atypical (n=2) urothelial cells showed mutations. None of the ileal conduit urine samples (n=2) with degenerated urothelial cells suspicious for malignancy showed mutations. Two of three cases with atypical urothelial cells suspicious for neoplasm in cytology had biopsies which showed high grade papillary urothelial carcinoma; one invasive and the other non-invasive. The latter case revealed a point mutation (G382R). Two cases proven by biopsy to be high grade UC or mixed high grade carcinoma were easily diagnosed as UC in cytology; however neither showed an FGFR3 mutation. An intronic mutation near exon 15 was identified.
Conclusions: Our results indicate that bladder washings can be suitably processed for FGFR3 mutation analysis in conjunction with cytopathological analysis. Extension of this study with more sensitive point-mutation specific assays in combination with urine cytology could increase the diagnostic sensitivity of detection of NMI UC.
Monday, March 19, 2012 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 66, Monday Morning