EGFR and non-small cell lung carcinoma: A retrospective study conducted in Saudi also showed that TKD, which spans exons 18 to 21, was mutated in approximately 57% of HNCs and its mutation was correlated with a higher grade of HNC, implying that EGFR mutations, which are known predictors of response to therapy in NSCLC, might be extrapolated to HNC [18].