Epidermal growth factor receptor gene mutation status in pure squamous-cell lung cancer in Chinese patients

Abstract

Background: Although new individual treatments continue to reshape the landscape of clinical care in patients with lung cancer, most of the progress has been mainly of benefit to patients with lung adenocarcinomas rather than squamous cell lung carcinoma (SQCLC). Our study aimed to determine whether the epidermal growth factor receptor (EGFR) gene mutation is present in pure SQCLC. We further determined the mutation frequency and the clinical and pathological features of groups that are in high risk for EGFR mutation.

Methods: A total of 185 Chinese patient specimens diagnosed as SQCLC in the Shanghai Chest Hospital at the Shanghai Jiao Tong University were selected for this study. Hematoxylin-eosin stained slides for all cases were reviewed and evaluated by immunohistochemical analysis with the aim of selecting samples with pure SQCLC. After screening, 22 cases were eliminated and 163 pure SQCLC cases remained. Amplification Refractory Mutation System was used to detect the EGFR gene mutation status in the 163 SQCLC specimens.

Results: A total of 28 cases with EGFR mutation were detected among the 163 specimens. The EGFR mutation rate was 17.2% (28/163). Sex and smoking status were significantly associated with the status of EGFR gene mutation (P = 0.022 and P = 0.049, respectively). Age and degree of differentiation were not significantly correlated to EGFR mutation (P = 0.730 and P = 0.651, respectively).

Conclusions: EGFR mutations are present in pure SQCLC, which are more frequently detected in females and nonsmoker patients. Our results indicate the importance for all patients with SQCLC to have EGFR mutation status examined. These patients with activating EGFR mutation could accept tyrosine kinase inhibitors (TKIs) treatment.

Figure 1

Method for obtaining pure SQCLC tissues for detection ofEGFRgene mutation. [A] HE stained slice diagnosed as SQCLC. [B] TTF-1 staining of the residual alveolar epithelium. When obtaining the SQCLC tissues for mutation analysis, the positive regions (indicated by green borders) were avoided. [C] ∆NP63 staining. The region outlined by the green border was used to detect the EGFR gene mutation status.

Figure 2

A poorly differentiated adenocarcinoma with squamous morphology. [A] The HE stained specimen from this case could be diagnosed as poorly differentiated SQCLC without IHC analysis. [B] Positive TTF-1 stained specimen from the same case.