FISH as a Cancer Risk Biomarker on ThinPrep Rectal Cytologic Brushings in Ulcerative Colitis (UC): A Promising Alternative to Biopsy-Based FISH.
Deepa T Patil, Jennifer Lewis, Bonnie Shadrach, Megan Settle, Barbara Ozimek, Nancy Ray, Jennifer Brainard, Tricia Pua, Mary Bronner. Cleveland Clinic
Background: Neoplastic progression in inflammatory bowel disease results in widespread mucosal chromosomal alterations detected by FISH on mucosal biopsies, including nondysplastic rectal samples. Rectal brushing may be an attractive alternative compared to colonoscopic biopsies, since it does not require endoscopy and may be less subject to sampling error. In this study, we evaluate the feasibility of FISH as a neoplastic biomarker on nondysplastic UC rectal brushings.
Design: Nondysplastic rectal brushings using standard cytology brushes and corresponding biopsies were obtained from surgical resections from 2 UC-progressors [(P), with multifocal high-grade and low grade-dysplasia and one with multifocal cancer in addition], 3 UC-nonprogressors (NP) without neoplasia and 2 non-UC controls. Two techniques were compared on ThinPrep (Hologic) processed rectal brushings: A) FISH without epithelial isolation, and B) FISH with epithelial isolation using tyramide-enhanced fluorescent cytokeratin immunohistochemistry plus FISH. Epithelial isolated touch preparations from corresponding rectal biopsies were also processed for FISH. Dual Vysis FISH probes targeting cyclin D1 and its matched CEP11 centromere were used and 100 epithelial cells/slide were enumerated per sample. A Pap-stained slide was additionally prepared for each brushing sample to assess for inflammatory activity and lack of neoplastic change.
Results: All UC cases had active rectal inflammation. The number of cells with FISH abnormalities (arm or centromere gains or losses) was significantly higher in UC-P (touch prep and ThinPrep with and without epithelial isolation) compared to UC-NP and non-UC controls (18%, 46%, 34% vs. 9%, 6%, 8% vs. 4%, 4%, 4%, p=0.0001). While all three methods distinguished UC-P's from UC-NP's, the difference was most pronounced with the ThinPrep method compared to biopsy touch preparations (p= 0.0001 vs 0.02), irrespective of whether epithelial isolation was used or not on the ThinPrep.
Conclusions: FISH chromosomal gains and losses on rectal cytologic brushings from UC patients shows promise as a biomarker and may be an improvement over biopsy testing. ThinPrep brushings may also potentially eliminate the need for epithelial isolation. This technique must still be adapted to in vivo patient brush rectal sampling, as these preliminary results were obtained from ex vivo surgical resections. The findings are nonetheless novel and suggest that far less invasive cytology preparations could better target UC patients at highest risk of neoplastic progression using FISH biomarkers.
Wednesday, March 2, 2011 9:30 AM
Poster Session V # 28, Wednesday Morning