Utilization of cytologic cell blocks for targeted sequencing of solid tumors

BACKGROUND: Targeted sequencing of cytologic samples has significantly increased in recent years. With increasing numbers of clinical trials for variant specific therapeutics, validating a comprehensive assay for cytologic samples has become clinically important. AIM: For this study, a retrospective review of cytologic cell blocks from fine needle aspirations and fluid specimens was performed. METHODS: Two hundred twenty six total cases of solid tumor malignancies were identified, of which 120 cases and 20 lymph node negative controls were sequenced for the Oncomine Comprehensive Assay. Cytology and surgical specimen correlation was performed in a subset of cases. Statistical analysis to determine variant concordance was performed. RESULTS: Within the 117 cases sequenced, a total of 347 pathogenic variants were detected. Of the 117 cases, 32 cases (27.4%) would qualify for FDA approved targeted therapy according to the current guidelines, and an additional 23 cases (19.7%) would qualify for clinical trial based on pathogenic variants detected. DISCUSSION: With over 27% of cases in our cohort qualifying for some form of targeted therapy, our study shows the importance of providing comprehensive molecular diagnostic options. Despite only half of the cytology cases in the review period having enough material to be sequenced, overall approximately 27% of patients in this cohort would have benefitted from this service.