ABSTRACT
Objectives: Pleural fluid evaluation is an effective modality for identifying actionable genetic mutations to guide therapy in lung carcinoma. Clinicians requesting molecular studies often send large volumes of fluid to be processed that is not possible or cost effective and is hence not standard of practice in most cytopathology laboratories. We wanted to establish the characteristics of an adequate specimen that would yield reliable results with current molecular testing platforms. Material and Methods: A review of 500 malignant pleural effusions, from pulmonary and non-pulmonary sources, was undertaken over a 4-year period. Of these 44 cases (from 42 patients) that were positive for primary lung adenocarcinoma were included in the study. Molecular analysis was performed on 42 specimens. A complete next generation sequencing (NGS) panel was performed on 36 specimens. Individual testing for estimated glomerular filtration rate, KRAS, anaplastic lymphoma kinase, and ROS1 was performed on six specimens. The number of malignant cells and proportion of tumor to non-tumor nucleated cells (T: NT) on cell blocks was recorded as <20%, 20-50% and >50%. Results: The minimum volume on which a complete NGS panel could be performed was 20 ml with cell count of 1000 and T: NT proportion of 20-50%. The minimum number of tumor cells required for successful molecular analysis for T: NT proportion of <20%, 20-50%, and >50% was 300, 250, and 170 cells, respectively. Conclusion: We concluded that tumor cell proportion, rather than specimen volume, is of prime importance for determining the efficacy of pleural fluid for molecular studies. Evaluation of both absolute and relative numbers of tumor cells is critical for assessing the adequacy and predicting successful yield for molecular analysis.
ABSTRACT
BACKGROUND: Myeloid cell leukemia-1 (Mcl-1) is a member of the B-cell lymphoma 2 family known to play a significant role in the regulation of apoptosis. Mcl-1 expression has been studied in nonsmall cell lung cancer (NSCLC) cell lines but has not been previously evaluated as a prognostic factor in clinical samples. MATERIALS AND METHODS: Formalin-fixed, paraffin-embedded sections from 119 NSCLC, including 33 squamous cell carcinomas (SCC), 55 adenocarcinomas (AC), and 31 either pure adenocarcinoma in situ (AIS) or AC with lepidic features were immunostained by an automated method with rabbit polyclonal Mcl-1. Cytoplasmic Mcl-1 (cMcl-1) immunoreactivity was scored based on intensity and percentage of positive tumor cells in both tumor and adjacent benign epithelium in each case. MCL1 amplification was determined by hybrid capture-based comprehensive genomic profiling (CGP) on a separate cohort of 9393 NSCLC samples. RESULTS: Intense diffuse cMcl-1 overexpression was noted in 35/119 (29%) tumors overall and correlated with tumor type (52% AIS vs. 31% AC vs. 6% SCC, P < 0.0001), tumor grade (48% grade 1 vs. 14% grade 2 vs. 31% grade 3, P = 0.007), small tumor size (36% ≤3.0 cm vs. 16% >3.0 cm, P = 0.016), and lengthened survival within the AIS subgroup (100% alive vs. 42% expired, P = 0.018) while showing a trend toward correlation with nonrecurrent disease overall (32% nonrecurrent vs. 11% recurrent, P = 0.072) and within the AC subgroup (33% nonrecurrent vs. 0% recurrent, P = 0.092). MCL1 amplification was identified in 569 (6%) of 9393 NSCLC by CGP. CONCLUSIONS: cMcl-1 overexpression appears to occur independently from MCL1 gene amplification in NSCLC and correlates with AIS histologic type, lower tumor grade, smaller tumor size, nonrecurrent disease, and increased survival.
