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H. La
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P2.04 - Poster Session/ Biology, Pathology, and Molecular Testing (ID 234)
- Event: WCLC 2015
- Type: Poster
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:
- Coordinates: 9/08/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P2.04-040 - Impact of Ethnicity on Incidence of Brain Metastasis in Patients with EGFR-Mutant Lung Cancer (ID 2981)
09:30 - 09:30 | Author(s): H. La
- Abstract
Background:
Better systemic control and longer survival have been cited as the reason for the higher incidence of brain metastasis observed in patients with EGFR-mutant lung cancer compared to patients with EGFR wild-type lung cancer. The prevalence of EGFR mutation is particularly dependent on patient’s ethnicity: 30-40% and 10-16% in East Asian and Caucasian patients, respectively. However, the incidence of brain metastasis in EGFR mutant lung cancer at initial diagnosis in these ethnic groups is less well defined. The objective of this study was to investigate the incidence of brain metastasis at diagnosis in East Asian and Caucasian patients with EGFR-mutant lung cancer.
Methods:
This retrospective study included 163 consecutive patients with EGFR-mutant metastatic NSCLC from a Chinese (N=72) and a US academic (N=91) institution. The EGFR mutation status was determined by the institutional laboratory in China and CLIA-certified laboratory in the US. East Asians in Northern California and Chinese patients in China had a similar incidence of brain metastasis at diagnosis (10/23=43.5% and 30/72=41.7%, respectively), and were combined as East Asians in the analysis. Descriptive statistics were generated for demographics, smoking habits, histology, and EGFR mutation subtypes, stratified by status of brain metastasis at diagnosis. Chi-squared tests and t-tests were used for testing associations of categorical variables and continuous variables with brain metastasis at diagnosis, respectively. Logistic regression models were used to study the association between race and brain metastasis at diagnosis, with and without adjusting for age at initial diagnosis, gender, EGFR mutation type, smoking status, and histology. Odds ratio (OR) and corresponding 95% confidence intervals (CI) were obtained. All analyses were two sided and a p value <0.05 were considered significant.
Results:
Three patients who were neither East Asian nor Caucasian were ineligible for analysis. Among the remaining 160 patients, 44.2% were Caucasians and 55.8% East Asians. Higher incidence of brain metastasis at diagnosis was detected in East Asian patients than Caucasian patients (42.1% vs 13.8%, p= 0.0001). There is no significant difference in the mean age (62 and 59 years old), smoking history (34.2% vs 26.5%), histology (93.8% adenocarcinoma in both groups), type of EGFR mutation (Exon 19 Deletion: 47.8% vs 48.0%; L858R: 35.4% vs 38.0%) between patients without brain metastasis and with brain metastasis at diagnosis. Comparing to Caucasians, East Asians had significantly higher incidence of brain metastasis at diagnosis (OR = 4.53, 95% CI: 2.01–10.20, p= 0.0003). The result remained significant after adjusting for other factors (aOR = 4.24, 95% CI: 1.76–10.18, p= 0.001).
Conclusion:
Regardless of place of residence (Northern California or China), East Asians were more likely to have brain metastasis at initial diagnosis than Caucasian patients, suggesting ethnicity-related genomic and pharmacogenomic differences and less impact of environmental factors on tumorigenesis and clinical course of EGFR-mutant lung cancer. Further study is indicated to understand the impact of ethnicity and population-related genomics and pharmacogenomics on tumor biology of EGFR-mutant lung cancer.
