Utility of Routine Bone Marrow Fluorescent in Situ Hybridization (FISH) Panel Testing in Patients Suspected of Myelodysplastic Syndrome (MDS): An Analysis of 3,418 Patients and Comparison of Academic Versus Community Practices
Authors: Karkera Amritha C , Laffin Jennifer , Go Ronald S. 
Published: October 2019

Abstract
Abstract 3855

Background:
Metaphase cytogenetics and FISH panel testing are commonly performed on bone marrow aspirate samples from patients suspected of having MDS. We performed this study to determine the frequency of simultaneous testing in academic versus community practices and whether routine FISH panel provides additional information to metaphase cytogenetics.

Methods:
After approval from our institutional review boards, a list of patients who had bone marrow aspirate samples submitted to the Wisconsin State Laboratory of Hygiene between January 2000 to June 2011, with a diagnosis of anemia, thrombocytopenia, neutropenia, or pancytopenia, and suspected MDS was obtained from Wisconsin State Laboratory of Hygiene. If multiple samples were submitted for the same patient, we included only the first sample. We collected data pertaining to demographics, indication/diagnosis, requesting institution, date of request, and cytogenetics/FISH results. The FISH panel included probes for chromosomes 5q31, 7q31, 8, and 20q (Abbott Molecular, Abbott Park, IL).

Results:
We included 3,418 patients who met our study criteria. The median age was 57.5 years (18–97 years) and 55.2% were males. The samples came from 1 academic center (36.9%), 4 community practices (44.7%), and 3 referral laboratories (18.4%). The top clinical indications for bone marrow aspiration were anemia (48.5%), pancytopenia (26.8%), thrombocytopenia (15.2%), neutropenia (5.2%) and possible MDS (2.3%). Karyotype was normal in 2,527 (73.9%), abnormal in 617 (18.1%), and could not be determined in 274 (8.0%) due to culture failure or inadequate karyotypes.
Simultaneous testing for cytogenetics and FISH was performed in 379 patients (11.1%). In this subgroup, abnormal karyotypes were identified in 64 (16.8%) and abnormal FISH results in 55 (14.5%). Among the 299 samples which had adequate metaphases for cytogenetic analysis, FISH panel detected additional cytogenetic abnormalities in 11 (3.6%) patients. The cytogenetic abnormalities detected by FISH but not by karyotyping were −20q (5 patients), −7q (4 patients), −5q (1 patient), and −5q/-20q (1 patient). However, this would have changed the MDS International Prognostic Scoring System karyotype score in only 5 of these patients (1.7%) patients. In cases with inadequate karyotypes or no growth (n = 80), abnormal FISH result was found in 13 (16.2%). The cytogenetic abnormalities detected were −20q (4 patients), −7q (4 patients), −5q (3 patients), −5q/-7q/-20q (1 patient) and −5q/-7q (1 patient).
The karyotype inadequacy/failure rates were similar regardless of whether samples came from academic center or the community (8.7% vs 7.6%; P = 0.277). However, community physicians were more likely to perform simultaneous cytogenetic and FISH testing compared to academic physicians (14.0% vs 6.2%; P < 0.0001). FISH testing detected additional abnormalities at a similar rate among samples coming from the academic and community practices (2.6% vs 7.3%; P = 0.190). There was a significant variability in the rates of simultaneous cytogenetic and FISH testing among community practices ranging from 0% to 23.4% (P < 0.0001).

Conclusions:
In our study of a large sample of patients being evaluated for cytopenias and suspected of MDS, routine bone marrow FISH panel testing added little to cytogenetic study except when karyotype failed or was inadequate. Community physicians requested simultaneous testing for cytogenetics and FISH significantly more often than their academic counterparts even though karyotype inadequacy or failure rate was similar. There was a large variation in simultaneous testing rates among community practices.

Disclosures:
No relevant conflicts of interest to declare.