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Distinctive Evaluation of Nonmucinous and Mucinous Subtypes of Bronchioloalveolar Carcinomas in EGFR and K-ras Gene-Mutation Analyses for Japanese Lung Adenocarcinomas
Confirmation of the Correlations With Histologic Subtypes and Gene Mutations

Yuji Sakuma MD, PhD, Shoichi Matsukuma PhD, Mitsuyo Yoshihara, Yoshiyasu Nakamura, Kazumasa Noda MD, PhD, Haruhiko Nakayama MD, PhD, Yoichi Kameda MD, PhD, Eiju Tsuchiya MD, PhD, Yohei Miyagi MD, PhD
DOI: http://dx.doi.org/10.1309/WVXFGAFLAUX48DU6 100-108 First published online: 1 July 2007

Abstract

Although adenocarcinomas of the lung are associated with epidermal growth factor receptor (EGFR) gene mutations and sensitivity to EGFR tyrosine kinase inhibitors, it remains unclear whether bronchioloalveolar carcinoma (BAC) components and/or subtypes affect these associations. We aimed to clarify correlations between EGFR gene mutations and BAC components and to establish the histologic features as reliable predictors for the mutations. We examined 141 non–small cell lung cancers (NSCLCs), including 118 adenocarcinomas, for mutations in exons 19 and 21 of the EGFR gene together with mutations in codon 12 of the K-ras gene using loop-hybrid mobility shift assays, a highly sensitive polymerase chain reaction–based method. Adenocarcinomas were subdivided into subtypes with a nonmucinous or mucinous BAC component and those without BAC components.

In NSCLCs, EGFR mutations were detected in 75 cases (53.2%) and were significantly associated with adenocarcinoma, female sex, and never smoking. Among adenocarcinomas, nonmucinous and mucinous BAC components were significantly associated with EGFR and K-ras gene mutations, respectively. Because EGFR mutations were detected even in most pure nonmucinous BACs, ie, lung adenocarcinoma in situ, EGFR mutation is considered a critical event in the pathogenesis of nonmucinous BAC tumors.

Key Words:
  • Lung
  • Adenocarcinoma
  • Bronchioloalveolar
  • EGFR
  • K-ras
  • Mutation
  • Loop-hybrid mobility shift assay