Demographic and clinical information of patients with non-small cell lung cancer and its relationship with EGFR gene mutation rates in Iranian population

Mutations in epidermal growth factor receptor (EGFR) gene are mainly observed in exons 18 to 21. Evaluation of mutations in the response to treatment of patients with non-small cell lung cancer (NSCLC) is more important than tyrosine kinase inhibitors (TKIs) and the frequency of EGFR gene mutations varies in NSCLC patients in different geographical regions of the world.

  In this study, exons 18 to 21 of the EGFR gene were studied in 160 patients with NSCLC. For this purpose, DNA was extracted from paraffin block, PCR and then sequencing was performed and the results were analyzed.

The prevalence ratio of NSCLC in male to female patients was about 2 to 1 and there was no significant difference in age between male and female patients (P = 0.065), while a significant difference was found in the smoking variable (77.8 men and 17.3% women). The frequency of mutations for exons 19 and 21 of EGFR gene was 10.63% and no mutations were found for exons 18 and 20. On the other hand, women were more sensitive to EGFR mutations than men (17.3% versus 7.4%), however this difference was not statistically significant (P=0.097). In this study, 3 mutations including (c.2235_2249del) and (c.2240_2257del) in exon 19 and (c.2573T> G) p. L858R in exon 21 were observed with frequencies of 58.8, 23.5 and 11.8%, respectively. Also, an alternative mutation including (c.2253 A> G) was found as a new mutation for the first time, which was the rarest mutation with a frequency of 5.8%. Interestingly, a negative relationship was observed between the mutation rate in EGFR gene and smoking of infected people that according to other studies in different countries, diversity in ethnicity can be assumed as the cause of these findings.

The results of this study showed that probably due to differences in ethnicity, smoking rate and gender of patients the occurrence of EGFR gene mutation varies greatly between different regions of Iran.