9. Best practices for testing and reporting of FISH studies in multiple myeloma: Recommendations from the CGC working group

Purpose

Multiple myeloma (MM) remains an incurable plasma cell malignancy with recurrent primary and secondary cytogenetic abnormalities having prognostic and therapeutic implications. Fluorescence in situ hybridization (FISH) is the gold-standard assay to detect these genetic abnormalities. However, FISH testing for MM is heterogeneous among clinical laboratories, with differences in plasma cell isolation, FISH panel design, and reporting practices.

Methods

The CGC Plasma Cell Neoplasm workgroup conducted a survey targeting the international MM clinician community on utilization of FISH and result reporting/interpretation.

Results

There were 102 survey responses representing 14 countries. Most (74%) MM clinicians utilize their own in-house FISH testing service with 81% reporting plasma cell enrichment was performed by their lab. 90% of respondents desired FISH at diagnosis, 72% during disease progression and 40% for treatment/response assessment. The most-requested FISH 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%). About 40% of respondents were dissatisfied with clarity, summary, and interpretation of FISH reports. When challenged to interpret a FISH report, only 2% of responders interpreted results correctly and the majority were either unsure or misinterpreted the report.

Conclusion

Our study showed that significant improvements are needed by clinical lab directors in MM FISH report clarity to benefit both the clinician and patient. We propose standardization of best MM FISH practices and reporting.