title: Survival outcome assessed according to tumor response and shrinkage pattern in patients with EGFR mutation-positive non-small-cell lung cancer treated with gefitinib or erlotinib.
abstract: BACKGROUND
  Somatic mutations in the epidermal growth factor receptor gene (EGFR) are associated with a marked therapeutic response to EGFR-tyrosine kinase inhibitors (TKIs) in patients with advanced non-small cell lung cancer (NSCLC). Clinical indicators of the likely survival benefit of EGFR-TKI treatment in NSCLC patients with EGFR mutations have not been identified, however. We therefore evaluated progression-free survival (PFS) and overall survival (OS) according to tumor response and tumor shrinkage pattern in such patients.
  
  
  METHODS
  Among 145 EGFR mutation-positive NSCLC patients treated with EGFR-TKIs, 68 individuals were selected for analysis.
  
  
  RESULTS
  Of the 68 selected patients, 6 achieved a complete response (CR), 42 a partial response (PR), and 14 stable disease (SD). Both PFS and OS were significantly longer in patients who achieved a CR or PR than in those who experienced SD. Multivariate analysis showed that a response (CR or PR) to EGFR-TKIs was significantly associated with both PFS and OS. Among the CR/PR group, the median maximal tumor shrinkage relative to baseline was 56%, and the median time to response (TTR) was 4.2 weeks. The subsets of these patients who experienced rapid tumor regression (TTR of ≤4.2 weeks) or a high degree of tumor shrinkage (≥56%) did not show a more favorable PFS or OS compared with those who experienced slow tumor regression or a low degree of tumor shrinkage.
  
  
  CONCLUSIONS
  Response (CR or PR) may represent the optimal surrogate for efficacy among EGFR mutation-positive NSCLC patients treated with EGFR-TKIs.
authors.affiliation: *Department of Medical Oncology, Kinki University Faculty of Medicine, Osaka, Japan; †Department of Medical Oncology, Kishiwada City Hospital, Osaka, Japan; and ‡Center for Clinical and Translational Research, Kyushu University Hospital, Fukuoka, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Takeda
authors.forename: Isamu
authors.initials: I
authors.lastname: Okamoto
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Nakagawa
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000235:genetics / Q000401:mortality; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000235:genetics / Q000401:mortality*; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000235:genetics / Q000401:mortality; D066246:ErbB Receptors / Q000235:genetics*; D000069347:Erlotinib Hydrochloride; D005260:Female; D005500:Follow-Up Studies; D000077156:Gefitinib; D005838:Genotype; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D009367:Neoplasm Staging; D016133:Polymerase Chain Reaction; D011379:Prognosis; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use; D011799:Quinazolines / Q000627:therapeutic use*; D015996:Survival Rate
chemical_list: D000970:Antineoplastic Agents; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D000069347:Erlotinib Hydrochloride; C512478:EGFR protein, human; D066246:ErbB Receptors; D000077156:Gefitinib