Hyun-Ju Lee MD, PhD, Presenter: Nothing to Disclose

Young Tae Kim MD, PhD, Abstract Co-Author: Nothing to Disclose

Chang Hyun Kang, Abstract Co-Author: Nothing to Disclose

Binsheng Zhao DSc, Abstract Co-Author: Nothing to Disclose

Yongqiang Tan PhD, Abstract Co-Author: Nothing to Disclose

Lawrence H. Schwartz MD, Abstract Co-Author: Consultant, GlaxoSmithKline plc Consultant, F. Hoffmann-La Roche Ltd

Thorsten Persigehl MD, Abstract Co-Author: Nothing to Disclose

Doo Hyun Chung MD, PhD, Abstract Co-Author: Nothing to Disclose

To retrospectively identify quantitative CT features that correlate with EGFR mutation status in surgically resected lung adenocarcinomas (ADs) stratified by IASLC/ATS/ERS classification

In 153 surgically resected lung ADs, EGFR mutation status was determined by direct DNA sequencing and categorized into exon 19 deletion, exon 21 missense, and exon 18 or 20 mutations. Histologic subtypes were classified according to IASLC/ATS/ERS classification of lung ADs. On preoperative chest CT, the GGO volume percentage (%) and total tumor volume of each tumor were measured using a semiautomated algorithm (watershed transformation with active contours and Markov random field based on density distribution). Distribution of EGFR mutation according to histologic subtype, GGO volume % and total tumor volume was evaluated. Statistical comparisons were performed using the Chi-square, one-way ANOVA, and two-sided Chi-square trend tests.

The exon 21 missense mutation was significantly more frequent in lepidic predominant ADs (AD in situ, minimally invasive AD, and lepidic predominant invasive AD) than in the other subtypes of dominant histology (acinar-, papillary-, micropapillary-, and solid-predominant as well as invasive mucinous AD) (P=0.0002). GGO volume % with the exon 21 missense mutation (62±32%) was significantly higher than that in EGFR wild type tumors (30±38%) (P=0.0001) and exon 19 mutated tumors (29±38%) (P=0.0006). A significant trend was found that the prevalence of exon 21 missense mutation increased along with increasing GGO volume % (P=0.0008); no trend was found in exon 19 deletion (P=0.168). There were no differences in total tumor volume among tumors with exon 21 missence (10±13 cm3), exon 19 deletion (8.7±8.4 cm3), and EGFR wild type (14±30 cm3) (P>.05). No trend was found that the prevalence of any type of EGFR mutation increased as total tumor volume increased or decreased (P>0.05).

The prevalence of EGFR exon 21 missense increased along with increasing GGO volume %. This can be supported by the fact that exon 21 missense was significantly more frequent in LPAs according to IASLE/ATS/ERS classification.

Identification of the relationship between CT features and EGFR mutation can help to define categories of lung adenocarcinoma that have distinct radiologic, molecular, and pathologic characteristics.

Lee, H, Kim, Y, Kang, C, Zhao, B, Tan, Y, Schwartz, L, Persigehl, T, Chung, D, EGFR Mutation in Lung Adenocarcinomas: Relationship with CT Characteristics and Histologic Subtypes According to IASLC/ATS/ERS Classification.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12032744.html