Adequacy of CT-guided biopsies with histomolecular subtyping of pulmonary adenocarcinomas: influence of ATS/ERS/IASLC guidelines.

INTRODUCTION: As metastatic pulmonary adenocarcinomas are routinely investigated for EGFR, KRAS, and ALK mutations/rearrangement, adequacy of CT-guided trans-thoracic needle biopsies (TTNB) needs to be evaluated in respect with the 2011 ATS/ERS/IASLC guidelines.

METHODS: Two series of consecutive TTNB with 18-gauge needles performed before and after the publication of the ATS/ERS/IASLC guidelines, were retrospectively compared regarding their adequacy for histological sub-typing and EGFR/KRAS mutations and ALK rearrangement testing; the first series included 43 TTNB collected from January 2010 to February 2011, and the second one 48 TTNB collected from March 2011 to December 2012.

RESULTS: 28 women and 63 men were included; the 2 groups were comparable in age, in mean size of lesions (32.5 mm), and distance of the lesion from the pleura. By comparing the first to the second series, the number of biopsies increased from 1.6 to 1.85, their mean length increased from 10.9 to 12.5mm, and the mean number of stainings (TTF1, P63, CK5-6, mucins) per biopsy decreased from 2.6 to 1. Mean tumor cell percentage was 42%, mean total DNA extracted increased from 2.7 to 3.8 μg. In the first series, 85% of TTNB allowed EGFR exons 19 and 21 and KRAS mutations pyrosequencing and 72% additional EGFR exons 18 and 20 mutation analyses, versus 98% and 92% in the second.

CONCLUSIONS: With respect to ATS/ERS/IASLC guidelines, radiologists, biologists and pathologists have improved their practice; accordingly, CT-guided TTNB enable a precise histological sub-typing and provide sufficient DNA amount for genetic analyses.