MAGE qPCR improves the sensitivity and accuracy of EBUS-TBNA for the detection of lymphatic cancer spread.

INTRODUCTION

Microscopic examination of histologic slides or cytologic specimens of mediastinal lymph node samples obtained by diagnostic mediastinoscopy or endobronchial ultrasound-guided fine-needle aspiration (EBUS-TBNA) is routinely used for the staging of lung cancer patients. Therefore, we explored whether the detection of tumor-associated mRNA in lymph node samples from patients with suspected lung cancer adds diagnostic accuracy to conventional histopathological staging.

METHODS

We examined 202 lymph nodes obtained by EBUS-TBNA or mediastinoscopy from 89 patients with lung cancer. Lymph node samples from patients with nonmalignant disease were available as controls (60 samples from 31 patients). Real-time quantitative mRNA analysis was performed for melanoma antigen-A genes (MAGE-A 1-6, MAGE-A 12) using a LightCycler 480 instrument.

RESULTS

MAGE transcript levels in control and cancer patients differed widely, and the 95% confidence interval served to define the threshold between negative and positive samples. MAGE 1 to 6 transcripts were detected in 35 of 122 (28.7%) lymph nodes obtained by EBUS-TBNA and 16 of 80 (20.0%) lymph nodes obtained by mediastinoscopy. MAGE 12 transcripts were detected in 10 of 122 (8.2%) lymph nodes obtained by EBUS-TBNA and 9 of 80 (11.3%) lymph nodes obtained by mediastinoscopy. Although the accuracy of histopathological diagnosis after EBUS-TBNA and mediastinoscopy was 69.6% and 84.1%, respectively, it increased to 81.2% and 86.4%, respectively, when combined with MAGE-quantitative polymerase chain reaction.

CONCLUSIONS

The combination of EBUS-TBNA and MAGE-quantitative polymerase chain reaction increases the accuracy of tumor cell detection to the level seen with mediastinoscopy.