RESEARCH ARTICLE The Epidermal Growth Factor Receptor (EGFR / HER-1) Gatekeeper Mutation T790M Is Present in European Patients with Early Breast Cancer

The epidermal growth factor receptor (EGFR) is one of the major oncogenes identified in a variety of human malignancies including breast cancer (BC). EGFR-mutations have been studied in lung cancer for some years and are established as important markers in guiding therapy with tyrosine kinase inhibitors (TKIs). In contrast, EGFR-mutations have been reported to be rare if not absent in human BC, although recent evidence has suggested a significant worldwide variation in somatic EGFR-mutations. Therefore, we investigated the presence of EGFR-mutations in 131 norwegian patients diagnosed with early breast cancer using real-time PCRmethods. In the present study we identified three patients with an EGFR-T790M-mutation. The PCR-findings were confirmed by direct Sanger sequencing. Two patients had triple-negative BC (TNBC) while the third was classified as luminal-A sub-type. The difference in incidence of T790Mmutations comparing the TNBC subgroup with the other BC subgroups was statistical significant (P = 0.023). No other EGFRmutations were identified in the entire cohort. Interestingly, none of the patients had received any pre-vious cancer treatment. To our best knowledge, the EGFR-T790M-TKI-resistance mutatio