Radiotherapy in lung adenocarcinoma with brain metastases: effects of activating epidermal growth factor receptor mutations on clinical response.
OBJECTIVE
Whole-brain radiation therapy (WBRT) has been applied to inoperable brain metastases in lung adenocarcinoma. Recently, an in vitro study showed reduced clonogenic survival of mutant epidermal growth factor receptor (EGFR) lung cancer cell lines in response to ionizing radiation compared with that of the wild type. To elucidate the role of EGFR mutations in radiation treatment, we evaluated the clinical response to WBRT and survival of lung adenocarcinoma patients with brain metastases.


METHODS
This was a retrospective analysis of 63 patients with brain metastases from lung adenocarcinoma who were treated with WBRT. Demographic data, EGFR mutation status, response to WBRT, and survival data were collected. Clinical response was assessed 1 month after the start of WBRT. Univariate and logistic regression models were used to test potential predictive factors associated with clinical response. Log-rank test and Cox regression were analyzed to identify factors that affected survival.


RESULTS
Clinical response to WBRT was observed in 29 patients (46%), with 34 nonresponder patients (54%). Patients with EGFR mutations had higher response rates to WBRT compared with those with the wild-type (54% versus 24%; P = 0.045). Both the administration of EGFR tyrosine kinase inhibitor (P = 0.034) and EGFR mutation (P = 0.029) were independently associated with response to WBRT. In Cox regression analysis, WBRT responder (P = 0.010) and absence of extracranial metastases (P = 0.002) were associated with better survival.


CONCLUSIONS
Both the EGFR mutations and the administration of EGFR TKI during WBRT were independent predictors of response to WBRT in brain metastases of lung adenocarcinoma.
Gow
Chien-Hung
CH
Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.
Chien
Chun-Ru
CR
Chang
Yih-Leong
YL
Chiu
Yueh-Hsia
YH
Kuo
Sung-Hsin
SH
Shih
Jin-Yuan
JY
Chang
Yeun-Chung
YC
Yu
Chong-Jen
CJ
Yang
Chih-Hsin
CH
Yang
Pan-Chyr
PC
D000230:Adenocarcinoma / Q000235:genetics / Q000532:radiotherapy* / Q000556:secondary; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000235:genetics / Q000532:radiotherapy* / Q000556:secondary; D003131:Combined Modality Therapy; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D066246:ErbB Receptors / Q000235:genetics*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011836:Radiation Tolerance / Q000235:genetics*; D012189:Retrospective Studies; D012907:Smoking
D004791:Enzyme Inhibitors; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases