Molecular Testing for Lung Adenocarcinoma: Concordance between Cytology and Histology
Jonas J Heymann, William A Bulman, Roger A Maxfield, Charles A Powell, Balazs Halmos, Mark Stoopler, Joshua Sonett, Nike T Beaubier, Anna M Babiac, Alain C Borczuk, Mahesh M Mansukhani, Saqi Anjali. Columbia University Medical Center, New York, NY
Background: Lung cancer is a leading cause of mortality, and patients often present at a late stage. Targeted therapies have become available for adenocarcinoma (ADCA) with epidermal growth factor receptor (EGFR) mutation. Greater numbers of minimally invasive procedures with smaller sample size, including transthoracic CT- and endobronchial ultrasound (EBUS)-guided FNAs, are being performed for diagnosis and determination of EGFR as well as KRas status. These markers can be evaluated on cytology specimens, but no comparison of results between cytology and corresponding histology specimens has been performed. This study aims to establish the validity of molecular testing (MT) on cytology samples by comparing their results with those on histology samples.
Design: Patients for whom both cytology and histology samples from the same or different site contain ADCA were identified retrospectively. MT was performed on formalin-fixed, paraffin-embedded samples. Exons 18-21 were amplified by PCR to detect EGFR mutations, and real-time PCR with allele-specific primers was used to detect common KRas mutations.
Results: Sixteen cytology – 9 EBUS- and 7 CT-guided FNAs – and 20 histology – 4 bronchoscopic, 4 other endoscopic, and 1 CT-guided core needle biopsies, as well as 11 resection specimens were identified from 14 patients. Sites sampled include lymph nodes (LN, n=8), lung masses (n=23), and other (n=5). Concordant results were obtained for all KRas (6/6) and 7/8 EGFR analyses performed on corresponding cytology and histology samples.