title: Solid predominant histology predicts EGFR tyrosine kinase inhibitor response in patients with EGFR mutation-positive lung adenocarcinoma.
abstract: BACKGROUND
  The efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) differs in patients with lung adenocarcinoma harboring EGFR-activating mutations. Although lung adenocarcinoma with EGFR-activating mutations has heterogeneous morphologic features, the predictive role of histologic subtype of lung adenocarcinoma with regard to the effectiveness of EGFR-TKIs in patients with EGFR-activating mutations has not been well defined.
  
  
  METHODS
  Among 134 postoperative recurrence patients with lung adenocarcinoma harboring EGFR-activating mutation (L858R or exon 19 deletion) treated with EGFR-TKIs, we retrospectively analyzed 61 patients treated with EGFR-TKIs as first-line chemotherapy. All the tumors were classified according to the new histologic classification proposed by the International Association for the Study of Lung Cancer (IASLC), American Thoracic Society (ATS), and European Respiratory Society (ERS) into the following subtypes: lepidic, papillary, acinar, micropapillary, or solid predominant subtype. We evaluated the correlation between the histologic subtype and the clinical efficacy of EGFR-TKIs.
  
  
  RESULTS
  In overall response rate, adenocarcinoma with solid predominant subtype is significantly worse than with non-solid predominant subtype (61 vs. 88 %, P = 0.03). The median progression-free survival (PFS) and overall survival after EGFR-TKI treatment were significantly shorter for the patients with solid predominant subtype than for those with non-solid predominant subtype (median PFS of 7.7 vs. 13.5 months, P = 0.002, and median OS of 21.5 vs. 31.0 months, P = 0.028).
  
  
  CONCLUSIONS
  This study indicated that among patients with lung adenocarcinoma harboring activating EGFR mutations treated with EGFR-TKIs, solid predominant subtype according to IASLC/ATS/ERS classification is a response predictor for EGFR-TKI.
authors: Division of Pathology, Research Center for Innovative Oncology, National Cancer Center Hospital East, 6-5-1 Kashiwanoha, Kashiwa, Chiba, 277-8577, Japan.
authors: Tatsuya
authors: T
authors: Yoshida
authors: Genichiro
authors: G
authors: Ishii
authors: Koichi
authors: K
authors: Goto
authors: Kiyotaka
authors: K
authors: Yoh
authors: Seiji
authors: S
authors: Niho
authors: Shigeki
authors: S
authors: Umemura
authors: Shingo
authors: S
authors: Matsumoto
authors: Hironobu
authors: H
authors: Ohmatsu
authors: Kanji
authors: K
authors: Nagai
authors: Yuichiro
authors: Y
authors: Ohe
authors: Atsushi
authors: A
authors: Ochiai
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D000077192:Adenocarcinoma of Lung; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D018572:Disease-Free Survival; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D000069347:Erlotinib Hydrochloride; D005260:Female; D000077156:Gefitinib; D006801:Humans; D053208:Kaplan-Meier Estimate; D008175:Lung Neoplasms / Q000235:genetics / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D009364:Neoplasm Recurrence, Local / Q000517:prevention & control*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D011799:Quinazolines / Q000494:pharmacology / Q000627:therapeutic use*; D017384:Sequence Deletion; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D000069347:Erlotinib Hydrochloride; C512478:EGFR protein, human; D066246:ErbB Receptors; D000077156:Gefitinib
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