Are PD-L1 and molecular markers from pleural fluid specimens reliable enough to guide decision making in metastatic NSCLC?

There is some good data to support the adequacy of malignant pleural effusion specimens as a source of tissue to detect actionable molecular and genetic alterations, if the cellularity of the cell block made from the fluid is adequate (Yang S-R, et al., J Mol Diagn 2018 is one such example). Many la...

In terms of molecular markers – pleural fluid is probably fine, though again, I am sending ctDNA on almost all newly diagnosed patients regardless. Regarding PD-L1: testing is not perfect, and I try to take this into account with all therapeutic decision-making. PD-L1 score can vary a lot by site of...

Agree that NGS testing can be done if the specimen (cell block) is adequate. PDL-1 testing is a bit more complex given known interobserver and tumor site heterogeneity. However, a recent review article showed good correlation between cytology vs tissue-based PDL-1 testing (Mansour et al., PMID 34233...

Depending on how the specimen is prepared and the number of cells, often PD-L1 and moleculars are able to be performed based on pleural fluid specimens. If I am worried the sample will be insufficient, I will send a liquid biopsy (which unless the molecular results are complete, I typically send any...