Molecular yield and cytomorphologic assessment of fine needle aspiration specimen supernatants

Introduction: Cytology samples are frequently relied upon for the diagnosis of advanced cancer such as lung cancer. As the recommendations for solid malignancies biomarker testing continue to expand, it becomes increasingly important to efficiently utilize limited specimens to minimize the need for additional sampling and its associated risks and costs.

Materials and methods: We performed molecular testing on fresh or CytoLyt-fixed supernatants derived from fine needle aspirates (FNAs) and compared its performance against the clinical specimen (including formalin-fixed paraffin-embedded cell blocks, residual PreservCyt and fresh samples). Supernatants were assessed for cellularity using Field-stained Cytospin (CS) preparations.

Results: There was overall almost perfect agreement (41/45 cases, K = 0.822) and substantial to almost perfect agreement in molecular testing results of clinically actionable variants between fresh (20/23 cases, Κ = 0.742) and CytoLyt-fixed (21/22 cases, Κ = 0.908) and its clinical specimen counterpart. Interestingly, CS examination of the supernatants revealed viable tumor cells. Centrifugation for 1 minute at 300 rpm is optimal for overall or tumor cellularity recovery. Delayed molecular testing after 3, 4 and 7 days at 4 degrees Celsius showed identical molecular results.

Conclusions: We validated the use of supernatants derived from FNA cytology samples as a substrate for molecular testing using next-generation sequencing and other molecular techniques.