Negative-pressure pumping fluid as a cytological specimen for bronchoscopic diagnosis and molecular testing in lung cancer.

BACKGROUND

Small bronchoscopic biopsy specimens may be insufficient for molecular testing. Cytology preserves nucleic-acid quality but can be discordant with tissue-based malignant findings. We developed negative-pressure pumping fluid (NPPF), a cytological specimen generated from tissue by negative-pressure cycles, to enrich tissue-derived malignant cells.

METHODS

Patients undergoing bronchoscopy for suspected non-small cell lung cancer were prospectively enrolled. Biopsy tissue, bronchial lavage fluid (BLF), and NPPF were collected. Malignant cell detection was compared across specimens, and agreement with tissue was assessed by concordance rates and Cohen's κ. Cytological quality was scored across five domains. In predefined subsets, nucleic-acid yields were compared before and after pumping, and mutation profiling using the MINtS assay was performed on NPPF and BLF when either specimen was cytology-positive.

RESULTS

Ninety-nine patients were analysed. Concordance with tissue for malignant cell detection was higher for NPPF than for BLF (90.9% vs 71.7%; κ = 0.75 vs 0.35). The combined BLF/NPPF result, defined as positive when either specimen was positive, closely matched the conventional combined tissue/BLF result (94.9%; κ = 0.81). NPPF scored higher than BLF for minimal cell overlapping, background cleanliness, staining quality, and ease of focusing, whereas BLF showed more uniform cell distribution (all p < 0.001). Negative-pressure pumping increased nucleic-acid yields. In 33 cytology-positive cases, MINtS profiles were concordant between BLF and NPPF samples.

CONCLUSIONS

NPPF improved cytological quality and nucleic-acid recovery while preserving biopsy tissue. Its molecular utility requires validation, including direct tissue-NPPF comparison and cytology-negative cases.