EGFR Mutation Testing: Changing Patterns of Molecular Testing in Brazil

In Brazil, cancer is the second most common cause of death. Most patients in resource-limited countries are diagnosed in advanced stages. Current guidelines advocate for EGFR mutation testing in all patients with metastatic adenocarcinoma. Tyrosine kinase inhibitors are recommended in patients with advanced or metastatic disease harboring sensitizing mutations. In Brazil, there are limited data regarding the frequency of EGFR testing and the changes in patterns of testing overtime.

This was an observational, retrospective study. We obtained deidentified data from a commercial database, which included 11,684 patients with non-small cell lung cancer treated between 2011 and 2016 in both public and private settings. We analyzed the frequency of EGFR mutation testing over time. We also directly studied 3,664 tumor samples, which were analyzed between 2011 and 2013. These samples were tested for EGFR mutations through an access program to tyrosine kinase inhibitors in Brazil.

Overall, 38% of patients were tested for EGFR mutations; 76% of them were seen in the private sector, and 24% were seen in the public center. The frequency of testing for EGFR mutations increased significantly over time: 13% (287/2,228 patients) in 2011, 34% (738/2,142) in 2012, 39% (822/2,092) in 2013, 44% (866/1,972) in 2014, 53% (1,165/2,184) in 2015, and 42% (1,359/3,226) in 2016. EGFR mutations were detected in 25.5% of analyzed samples (857/3,364). Deletions in Exon 19 were the most frequent mutations, detected in 54% of patients (463/857).

Our findings suggest that the frequency of EGFR mutation in this cohort was lower than that found in Asia but higher than in North American and Western European populations. The most commonly found mutations were in Exon 19 and Exon 21. Our study shows that fewer than half of patients are being tested and that the disparity is greater in the public sector.

These data not only indicate the shortage of testing but also show that the rates of positivity in those tested seem to be higher than in other cohorts for which data have been published. This study further supports the idea that awareness and access to testing should be improved in order to improve survival rates in lung cancer in Brazil.