In this large real-world cohort of advanced stage NSCLC from a tertiary hospital in Korea, 39.5% of patients were tested for EGFR
mutation. The frequency of testing increased over time, such that between October 2009 and July 2010 the proportion of patients referred for testing was 63.5%. Since most histologic diagnoses were based on a small amount of specimen obtained from bronchoscopy, needle biopsy, and aspiration, the testing rate during this period can be considered high. Indeed, Lynch et al. concluded in 2010 that EGFR
mutation testing was vastly underused in American NSCLC patients 
In our center, EGFR mutation testing was requested more frequently and more promptly over the years. Two factors may have influenced these time trends. First, our center developed the logistic capabilities for performing both histology and EGFR testing in the same pathology laboratory, thus reducing request complexity and turn-around times. Second, in agreement with the publication of landmark studies and national practice guidelines, different members in multidisciplinary NSCLC care teams at our center, including medical oncologists, pulmonologists, thoracic surgeons, and pathologists, agreed to the importance of improving the clinical performance of EGFR mutation testing.
We also found that request rates for EGFR mutation testing were associated with a number clinical characteristics of study patients. Test requests were more likely in patients with adenocarcinoma, and in those who were younger, female, never/former smokers, or who were ambulatory on admission. The association between request rates with age or performance status was likely due to concerns on side effects and complications associated with more aggressive biopsy procedures required to obtain specimens for EGFR mutation testing in patients with poorer performance status.
The NCCN guidelines do not recommend EGFR
mutation testing in squamous cell carcinoma 
. A previous study conducted in Italy found no EGFR
mutations among 454 patients with squamous cell carcinoma 
. In contrast, our study found that 6 out of 54 patients (11.1%) with squamous cell carcinoma had EGFR
mutations, with an even higher prevalence in the subgroup of never smoker patients with squamous cell carcinoma (2 out of 12, or 16.7%). Recently, Tanaka et al. 
reported a case in which a male current smoker with an EGFR mutation positive squamous cell carcinoma and performance status 4 showed a marked response to first-line gefitinib therapy. Our findings suggest that EGFR
mutation testing should be considered even for squamous cell carcinoma patients in East Asian populations, although further studies need to better characterize the prevalence of EGFR
mutation testing in East Asian patients with squamous cell lung carcinoma.
Although our data showed that EGFR
mutation testing was quickly becoming a standard part of routine management in NSCLC patients in our center during 2010, several barriers to improve quality of care remained. First, additional coordination and logistic efforts are needed to decrease turn-around times from diagnosis of advanced NSCLC to EGFR
mutation test reporting in order to maximize its clinical utility. Second, even though EGFR
mutation testing provides key information for decision making in treating NSCLC patients, testing is not reimbursed in Korea, a country in which health care is largely covered by a single-payer public insurance system although provision of care is provided in private centers. With an approximate cost of US $200, the economic burden may discourage a number of NSCLC patients from getting EGFR
testing. Reimbursement of EGFR
testing by insurance is important to further extend testing, particularly since more active molecular analyses, which search for additional predictive biomarkers such as EML4-ALK translocations 
, are becoming clinically available.
Our study was limited to a single tertiary hospital in Seoul, with a large volume of inpatient and outpatient consultations. Our findings may not be generalizable to countries outside of East Asia or to lower volume centers. However the key findings in our study, including the prevalence of EGFR mutations and the clinical characteristics of mutation positive patients, are expected to be similar to other major East Asian medical facilities. The retrospective nature of our study is also a potential limitation. Several strengths, however, including the large number of patients, the evaluation of consecutive patients in a real-world practice setting, and the availability and extraction of detailed clinical notes regarding testing procedures, add to the relevance of our findings.
Recently, Sun et al. 
reported that the frequency of the EGFR gene mutation is quite high among Korean patients with adenocarcinoma (up to 68.5% in nonsmoker women with adenocarcinoma) and even in male smokers with adenocarcinoma (29.7%). The current consensus recommends testing all newly diagnosed patients with advanced stage non squamous lung cancer, as well as some patients with squamous cell carcinoma with clinical features associated with higher prevalence of EGFR mutations in East Asia 
Finally, there are several issues in performance of EGFR mutation testing in practical environments, including sample type, techniques, turnaround time, and cost 
. Regardless of these issues, Gately et al. showed that testing performed in the same center where the patient has been pathologically diagnosed was associated with shorter testing lead times and lower probability of result misallocation 
In conclusion, in this comprehensive analysis of real-world practice regarding EGFR mutation testing in East Asia, we found that 39.5% of advanced NSCLC patients attending our center were tested for EGFR mutations from January 2007 to July 2010. The frequency of EGFR mutation testing increased over time, and by 2010 it had become part of the clinical workup in the majority of NSCLC patients. In accordance with the increase in the frequency of testing over time, the turn-around time from cancer diagnosis to EGFR mutation report progressively decreased, facilitating the clinical use of test results. Finally, while the prevalence of EGFR mutation positivity was 39% among adenocarcinoma patients, we found a that 11% of patients with squamous cell carcinoma also tested positive, suggesting that testing should be generalized to all NSCLC patients in East Asia.