title: Recurrent response to advanced lung adenocarcinoma with erlotinib developing leptomeningeal metastases during gefitinib therapy and two case reports.
abstract: BACKGROUND
  Epidermal growth factor-tyrosine kinase inhibitors (EGFR-TKIs) are one of the effective medicines in advanced lung adenocarcinoma leptomeningeal metastasis (LM) treatment in recent years.
  
  
  METHODS
  This paper reports two cases of advanced lung adenocarcinoma with exon-EGFR19 mutation. LM occurred during gefitinib treatment with an extracranial condition under control. Later, erlotinib was adopted with a recurrent response.
  
  
  RESULTS
  The progression free survival of both patients was over six months and their LM was under control for six and a half and nine months, respectively. LM may be sensitive on different levels to different EGFR-TKIs.
  
  
  CONCLUSIONS
  Erlotinib can be used to replace gefitinib if intracranial tumor progress occurs during gefitinib treatment. However, our conclusion still needs to be proven by further clinical research.
authors.affiliation: Chinese Academy of Medical Sciences & Peking Union Medical College, Cancer Hospital Beijing, China.
authors.forename: Puyuan
authors.initials: P
authors.lastname: Xing
authors.affiliation: Chinese Academy of Medical Sciences & Peking Union Medical College, Cancer Hospital Beijing, China.
authors.forename: Junling
authors.initials: J
authors.lastname: Li
authors.affiliation: Chinese Academy of Medical Sciences & Peking Union Medical College, Cancer Hospital Beijing, China.
authors.forename: Yuankai
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Chinese Academy of Medical Sciences & Peking Union Medical College, Cancer Hospital Beijing, China.
authors.forename: Xiangru
authors.initials: X
authors.lastname: Zhang
keywords: EGFR; LM; TKIs; erlotinib; lung adenocarcinoma