Suitability of Specimens from Pleural Dissemination of Non-Small Cell Lung Cancer for Genetic Testing Using Forceps and Cryobiopsy.

[INTRODUCTION] Pleuroscopy has significantly improved the diagnostic yield for pleural diseases, including lung cancer with pleural dissemination. However, obtaining suitable samples for genetic analysis in non-small cell lung cancer (NSCLC) remains challenging. Cryobiopsy enables the collection of larger specimens during pleuroscopy. This retrospective study evaluated the impact of incorporating cryobiopsy with forceps biopsy during pleuroscopy on specimen suitability and the success rate of genetic analysis.

[METHODS] This study included 37 patients with suspected malignant pleural effusion who underwent pleuroscopy with both cryobiopsy and forceps biopsy under local anesthesia at our institution between January 2020 and May 2024. The Oncomine Dx Target Test, a next-generation sequencing assay, was performed on all suitable specimens. Pleuroscopic findings included pleural thickening, granular lesions, small nodules, large nodules, and masses larger than 30 mm. Final pathological diagnoses included 23 cases of NSCLC, 5 cases of small cell lung cancer, 7 cases of malignant pleural mesothelioma, 1 case of diffuse large B-cell lymphoma, and 1 case of metastatic pancreatic cancer.

[RESULTS] The overall diagnostic yield of pleuroscopy was 97.3%. Cryobiopsy achieved a diagnostic yield of 97.3%, while forceps biopsy achieved 89.2 percent, with no statistically significant difference. The diagnostic yield plateaued after the fourth forceps biopsy and after the second cryobiopsy. In patients with NSCLC, specimens obtained by cryobiopsy were significantly more likely to be suitable for genetic analysis (49.1%) than those obtained by forceps biopsy (24.7%; p = 0.004). The combined suitability for genetic analysis of both forceps and cryobiopsy specimens was 69.6%, with a 100% success rate in performing the analysis. Larger pleural tumor size was significantly associated with higher specimen suitability (81.3% vs. 28.6%; p = 0.026). No complications requiring therapeutic intervention were observed.

[CONCLUSION] This exploratory study demonstrates that combining cryobiopsy with forceps biopsy during pleuroscopy improves specimen suitability for genetic analysis, with pleural tumor size emerging as a key determinant factor. Further prospective studies are warranted to validate these findings.