Optimal fluid volume for detecting malignancy in serous effusions: a single institution experience

Impact of serous fluid volume on next-generation sequencing: a significant step forward for optimization of serous fluid sample collection

Current literature lacks data regarding the influence of serous fluid volume (SFV) on next-generation sequencing (NGS) performed on malignant cases. In this study, we highlight the impact of SFV and other parameters influencing the outcome of NGS analysis. We evaluated 827 samples of serous fluids from 607 patients. Of these, 72 samples underwent NGS analysis. Effusion volume, tumor cellularity, DNA, and RNA quality metrics, as well as clinicopathologic and molecular data were evaluated. Pleural fluid accounted for 56.3% of the fluid samples collected. The most common primary tumor site was gastrointestinal/pancreatobiliary, adenocarcinoma was the most common histologic type. Overall mean volume was 293 mL. The mean Qubit DNA of the 72 effusion samples that underwent NGS analysis was 14.3 ng/μL and mean Qubit RNA was 28.2 ng/μL. The mean Qubit DNA concentration increases in SFV up to 100 mL only. No correlation exists between SFV and mean tumor cellularity. In addition, 74.6% (50 of 67) of sequenced samples showed oncogenic drivers; KRAS was the most common driver followed by EGFR. Three cases displayed ALK fusions, and 1 case displayed NTRK1 fusion. The DNA yield is higher in SFV of 100 mL as a cutoff. Beyond 100 mL, there is no impact of SFV on DNA yield. SFV does not impact RNA yield and mean tumor cellularity. Effusion samples should be submitted for molecular testing despite low tumor cellularity. Our results as a pilot study are important in optimization of SFV for both diagnosis as well as NGS analysis for improving management.

Optimal Volume Assessment for Serous Fluid Cytology

OBJECTIVE

This study aimed to investigate the optimal volume of serous fluid needed for accurate diagnosis using The International System for Reporting Serous Fluid Cytopathology (TIS), as well as to provide information on the distribution of serous effusion cases in the TIS categories (ND: non-diagnostic, NFM: negative for malignancy, AUS: atypia of undetermined significance, SFM: suspicious for malignancy, MAL: malignant) and relevant epidemiological data.

METHODS

A retrospective analysis of 2340 serous effusion cases (pleural, peritoneal, and pericardial) from two hospitals between 2018 and 2020 was conducted. TIS categories were assigned to each case, and for 1181 cases, these were correlated with the volume of the analyzed fluid.

RESULTS

Our study found statistically significant differences in volume distributions between certain TIS categories. Statistically lower volumes were observed in NFM compared to MAL, in UNCERTAIN (ND, AUS, SFM) compared to both MAL and NFM, and in NOT MAL (ND, NFM, AUS, SFM) compared to MAL. However, these differences were not substantial enough to hold any clinical relevance.

CONCLUSIONS

This study suggests that while fluid volume may slightly influence the TIS category, it does not impact the diagnostic accuracy of serous effusion cytology. Therefore, the ideal serous effusion specimen volume can be defined solely by practical parameters.

Malignant pleural disease

Malignant pleural disease represents a growing healthcare burden. Malignant pleural effusion affects approximately 1 million people globally per year, causes disabling breathlessness and indicates a shortened life expectancy. Timely diagnosis is imperative to relieve symptoms and optimise quality of life, and should give consideration to individual patient factors. This review aims to provide an overview of epidemiology, pathogenesis and suggested diagnostic pathways in malignant pleural disease, to outline management options for malignant pleural effusion and malignant pleural mesothelioma, highlighting the need for a holistic approach, and to discuss potential challenges including non-expandable lung and septated effusions.