P-197: Testing and Reporting of FISH Studies in Multiple Myeloma: Recommendations from the Cancer Genomics Consortium Myeloma Working Group for Best Practices

Introduction: Multiple myeloma (MM) is an incurable plasma cell (PC) malignancy with recurrent cytogenetic abnormalities with prognostic and therapeutic implications. The gold standard clilnical assay that detects these cytogenetic abnormalities is fluorescence in situ hybridization (FISH). FISH testing is heterogeneous among clinical laboratories, with variations in FISH panel design and reporting which can lead to confusion among physicians and patients. To assess the variability in MM FISH testing/and reporting, we formed the Cancer Genomics Consortium Plasma Cell Neoplasm Working Group composed of cytogenetic laboratory directors from a variety of clinical laboratory settings.

Methods: We formed a working group of cytogenetic laboratory directors from the Cancer Genomics Consortium membership. The directors represent a variety of clinical laboratory settings from small academic laboratories to large reference laboratories. We performed an extensive literature review and created a survey centered around the genetic testing practices and FISH report interpretation among MM clinicians.

Results: Among 102 respondents, representing 14 countries, most clinicians (74%) utilized in-house FISH laboratories. Nearly all (90%) respondents desired FISH at diagnosis, 72% during disease progression, and 40% for treatment/response assessment. The most-requested probes included TP53 (99%), t(4;14) (92%), 1q gain/amplification (91%), t(14;16) (90%), t(11;14) (85%) , t(14;20) (76%), 1p deletion (67%), while FISH for ploidy status, deletion 13q/-13, t(6;14), MYC rearrangement, and other rare IG rearrangements were ranked lower in importance (10-50%). Approximately 65% of respondents were satisfied with the clarity and interpretation of FISH reports. However, when challenged to interpret a particularly difficult FISH report, 20% responders interpreted results correctly while the majority were either unsure or misinterpreted the report.

Conclusions: Our study highlights the need for significant improvements in MM FISH report clarity by the clinical laboratory directors to benefit both the clinician and patient. We propose solutions to improve standardization and recommend best MM FISH reporting practices that we aim will be adopted by clinical laboratory directors.