[1269] Comparison of Fluorescence In-Situ Hybridization (FISH) and Conventional Cytogenetics (CC) in Acute Myeloid Leukemia (AML) and Myelodysplastic Syndrome (MDS)

G Aggarwal, E Manaloor, P Ramalingam. Medical College of Georgia, Augusta, GA

Background: Cytogenetic abnormalities are important for diagnosis, classification and treatment of AML and MDS. CC is now routinely ordered on all AML and MDS cases. Currently MDS and AML FISH panels are widely available and are being increasingly requested by oncologists for the work up of these cases. While in acute promyelocytic leukemia (AML-M3), FISH offers time-sensitive results necessary for the treatment, similar short turn-around times are not required for MDS and other AML subtypes. The aim of our study was to determine if FISH panels offered any additional data or information not identifiable by CC justifying the cost of its routine use.
Design: We identified 61 cases of AML and MDS that had both CC and FISH performed at our institution. FISH panels contained probes specific for the detection of abnormalities 5q, 7q, t(8;21), 13/12, inv 16, 20q12 and t(15;17). We analyzed the data for 1) most common abnormalities identified by both tests, 2) the cases in which FISH provided additional data not identified by CC, 3) the cases in which CC failed and FISH was positive and vice versa 4) cases where CC was positive but FISH was negative and vice versa.
Results: 33 of 61 cases (54%) were positive for cytogenetic abnormalities by either FISH and/or CC and 28/61 were negative by both tests. The most common abnormalities were del/monosomy of chr.5 and trisomy 8. There was no cell growth in 4 CC cases and of these FISH was negative in 3 but identified an abnormality in 1. Five cases negative by FISH showed abnormalities by CC. 26/33 (79%) cases revealed similar abnormalities both by FISH and CC; of these CC revealed additional abnormalities in 17 cases (52%). In 3 cases with a complex karyotype, FISH revealed trisomy 8, loss of CBFB at 16q22 and amplification of MLL gene not identified by CC. In 1 case, CC and FISH revealed entirely different abnormalities.
Conclusions: Both CC and FISH identified similar abnormalities in majority of cases. As expected, CC identified more abnormalities than FISH in approximately half the cases tested. Conversely, FISH identified significant additional abnormalities only in 2 cases. Our preliminary findings suggest that in most cases FISH panels for MDS and AML do not provide additional information compared to CC. Regular use of FISH is therefore best applied to the cases in which hematologic diagnosis is time-sensitive. Routine use of FISH panels appears not be cost-effective in MDS and most AML subtypes but needs to be evaluated in a larger series.
Category: Hematopathology

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 175, Tuesday Afternoon

 

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