[1540] Limited Diagnostic Utility of MDS FISH Testing in Myeloid Neoplasms at Diagnosis and Follow-Up

Adam C Seegmiller, Megan Kressin, Annette S Kim, Claudio A Mosse. Vanderbilt University Medical Center, Nashville, TN; Tennessee Valley Healthcare System, Nashville, TN

Background: Fluorescence in situ hybridization (FISH) studies for common genetic abnormalities seen in myelodysplastic syndrome (MDS) are commonly used with routine karyotype both for diagnosis and monitoring of myeloid neoplasms. Studies of the utility of FISH testing have been mixed, but a recent large study suggested that FISH rarely yields diagnostic information beyond that of an adequate karyotype. However, the performance of MDS FISH for monitoring disease has not been detailed. This study determines the concordance of MDS FISH and karyotype both at primary diagnosis and during therapy monitoring and evaluates the significance and outcome of discordant cases.
Design: A database of all adult bone marrow biopsies performed at Vanderbilt University Medical Center from 8/11/10 to 9/2/11 was queried for cases in which karyotype and FISH for at least one of four common MDS abnormalities (-5/5q-, -7/7q-, +8, 20q-) were performed. The results of each test were recorded and concordance between karyotype and FISH were determined. Clinical information was collected and evaluated for discordant tests.
Results: Karyotype and MDS FISH were performed on 416 cases, 148 for diagnosis and 268 for follow-up. At diagnosis, 36/148 cases had positive results. FISH was positive in a low percentage of cells (2-15%) in only 3 cases (2% of total) with normal karyotype. In 2 of these, the FISH abnormality was absent in subsequent marrows. In follow-up marrows, 10/268 (4%) had positive FISH results with negative karyotype. Most changes were at low levels (median 5.5% of cells positive), but in 9/10 cases, there was evidence that the positive test indicated residual disease. In 5 of these cases, the patient had overt persistent or recurrent disease in subsequent marrows. Furthermore, FISH tests performed at follow-up for cytogenetic abnormalities not seen at diagnosis were almost always negative (96%).
Conclusions: These data demonstrate that there is generally little or no additional benefit from MDS FISH in cases with an adequate karyotypic evaluation. In particular, there seems to be little benefit to performing MDS FISH at diagnosis or at follow-up if the tested abnormality was not present at diagnosis. However, during disease monitoring, there may be some added value to targeted FISH studies of abnormalities identified at diagnosis, as these may identify minimal residual disease and risk for persistent or recurrent disease.
Category: Hematopathology

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 230, Tuesday Morning

 

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