Abstract
BackgroundMultiple biomarker testing is necessary to facilitate individualized treatment of lung cancer patients. More than 80% of lung cancers are diagnosed based on very small tumor samples. Often there is not enough tissue for molecular analysis. We compared three minimal invasive sampling methods with respect to RNA quantity for molecular testing.Methods106 small biopsies were prospectively collected by three different methods forceps biopsy, endobronchial ultrasound (EBUS) guided transbronchial needle aspiration (TBNA), and CT-guided core biopsy. Samples were split into two halves. One part was formalin fixed and paraffin embedded for standard pathological evaluation. The other part was put in RNAlater for immediate RNA/DNA extraction. If the pathologist confirmed the diagnosis of non-small cell lung cancer(NSCLC), the following molecular markers were tested: EGFR mutation, ERCC1, RRM1 and BRCA1.ResultsOverall, RNA-extraction was possible in 101 out of 106 patients (95.3%). We found 49% adenocarcinomas, 38% squamouscarcinomas, and 14% non-otherwise-specified(NOS). The highest RNA yield came from endobronchial ultrasound guided needle aspiration, which was significantly higher than bronchoscopy (37.74±41.09 vs. 13.74±15.53 ng respectively, P = 0.005) and numerically higher than CT-core biopsy (37.74±41.09 vs. 28.72±44.27 ng respectively, P = 0.244). EGFR mutation testing was feasible in 100% of evaluable patients and its incidence was 40.8%, 7.9% and 14.3% in adenocarcinomas, squamouscarcinomas and NSCLC NOS subgroup respectively. There was no difference in the feasibility of molecular testing between the three sampling methods with feasibility rates for ERCC1, RRM1 and BRCA1 of 91%, 87% and 81% respectively.ConclusionAll three methods can provide sufficient tumor material for multiple biomarkers testing from routinely obtained small biopsies in lung cancer patients. In our study EBUS guided needle aspiration provided the highest amount of tumor RNA compared to bronchoscopy or CT guided core biopsy. Thus EBUS should be considered as an acceptable option for tissue acquisition for molecular testing.
Highlights
Lung cancer is the leading cause of cancer related mortality worldwide with .1.3 million estimated deaths in 2008 [1]
Non-small cell lung cancer (NSCLC) accounts for more than 80% of newly diagnosed cases, and most patients are diagnosed with advanced stage disease
While the tumor tissue for multiple biomarker testing is permanently increasing on one hand, the size of tissue samples on the other hand is rather decreasing with the advent of new minimal invasive diagnostic tools such as endobronchial ultrasound guided needle aspiration (EBUS-transbronchial needle aspiration (TBNA))
Summary
Lung cancer is the leading cause of cancer related mortality worldwide with .1.3 million estimated deaths in 2008 [1]. More 80% of patients are diagnosed on the basis of very small biopsies or cytology samples [6]. While the tumor tissue for multiple biomarker testing is permanently increasing on one hand, the size of tissue samples on the other hand is rather decreasing with the advent of new minimal invasive diagnostic tools such as endobronchial ultrasound guided needle aspiration (EBUS-TBNA). Given the small sample sizes obtained by routine lung cancer diagnostic procedures, tissue may already be expended after histopathological evaluation of the tumor and testing for EGFR mutation. Cytological samples obtained by EBUS have often been claimed as insufficient for molecular testing, especially in clinical trials and for research purposes. Multiple biomarker testing is necessary to facilitate individualized treatment of lung cancer patients. More than 80% of lung cancers are diagnosed based on very small tumor samples. We compared three minimal invasive sampling methods with respect to RNA quantity for molecular testing
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