Incidence of EGFR and K-ras mutations in Japanese patients with mucinous bronchiolo-alveolar cell carcinoma of the lung

Abstract

14553 Background: In lung adenocarcinomas, especially Bronchiolo Alveolar Carcinomas (BACs), it has been reported that Epidermal Growth Factor Receptor- Tyrosine Kinase Inhibitors (EGFR-TKIs) have a high potency. But in fact, its efficacy differs among subtypes: in mucinous BACs (mBACs), it exhibits a poor effect compared to its performance in non-mucinous BACs (non-mBACs). One reason why is EGFR mutations are rare, and K-ras mutations are frequent, in mBACs relative to non-mBACs. Methods: From January 2004 to October 2007, 180 lung adenocarcinomas were diagnosed in pathological specimens after resections. 51 cases (28%) of BACs were classified. In these specimens, 17 mBACs (9%) and 34 non-mBACs (19%) were found. We extracted 41 cases of BACs (all mBACs and 24 cases of non-mBACs as control), and examined their EGFR mutations and K-ras mutations. We used the PNA-LNA PCR clump method to detect EGFR mutations, and K-ras mutations were explored by sequences after the enriched PCR method. Results: Only three EGFR mutations were found in 17 mBACs (18%), and 12 K-ras mutations were present (71%). By comparison, 14 EGFR mutations were detected in 24 non-mBACs (58%), and 11 K-ras mutations were identified (46%). Conclusions: In mBAC cases, the efficacy of EGFR-TKIs is poor, because EGFR mutation is rare and K-ras mutation is frequent. No significant financial relationships to disclose.