SESSION TITLE: Lung Cancer
SESSION TYPE: Original Investigation Slide
PRESENTED ON: Tuesday, October 28, 2014 at 02:45 PM - 04:15 PM
PURPOSE: Adequate tumor acquisition in non-small-cell lung cancer (NSCLC) is essential to identify targetable somatic molecular alterations, such as EGFR mutations and ALK translocations. The success and failure rates for tumor genotyping of tissue obtained from pleural fluid cytology and surgically obtained pleural biopsies in routine NSCLC care have not been described.
METHODS: Clinicopathologic data and tumor genotype success and failure rates were retrospectively compiled and analyzed from patient-tumor samples sent for routine tumor genotype in clinical practice, including patient-tumor samples obtained from pleural fluid and surgical biopsies of the pleura.
RESULTS: From a cohort of 544 patient-tumor samples sent for genetic testing, tumor tissue was obtained from pleural fluid cytology or surgical pleural biopsies in 67 cases (12.3 % of total). In this latter cohort, the overall success rate for EGFR mutation analysis was 97% (n=67), for KRAS mutation 95.9% (n=47), and for ALK FISH 96.2% (n=54). Cytology-based malignant effusion samples made into formalin-fixed, paraffin-embedded cell blocks had a success rate of 95.1% (n=41) and surgical pleural biopsies had a success rate of 100% (n=26) for EGFR mutation analysis; failure rates were not significantly different when we compared pleural fluid cytology versus surgically obtained pleural biopsies (p=0.5152).
CONCLUSIONS: The success rate of multiple tumor genomic analyses techniques for EGFR, KRAS, and ALK gene abnormalities using routine pleural samples obtained from cytology-based cell blocks by means of thoracentesis exceeds 95%, and this method of tissue acquisition shows no statistically significant inferiority to surgically obtained pleural biopsies. Tumor genotype techniques are more than feasible in cytology-derived specimens that are positive for malignant cells, and therefore further expansion of routine tumor genotyping for the care of patients with NSCLC may be possible using targeted sample acquisition through minimally-invasive cytology samples of pleural fluid obtained by thoracentesis.
CLINICAL IMPLICATIONS: The pleural fluid cytology samples are comparable to surgically-obtained pleural biopsy tissue for genomic analysis of EGFR, KRAS and ALK. These results should guide therapeutic decisions in patients with NSCLC.
DISCLOSURE: The following authors have nothing to disclose: Erik Folch, Adnan Majid, Paul VanderLaan, Norihiro Yamaguchi, Sidhu Gangadharan, Michael Kent, Richard Whyte, Olivier Kocher, David Boucher, Mark Huberman, Michael Goldstein, Daniel Costa
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