Expression of CD44s and CD44v6 in lung cancer and their correlation with prognostic factors

Background: CD44, a transmembrane glycoprotein receptor, plays a major role in tumor progression and metastasis. Objective: To evaluate the expression of CD44 standard (CD44s) and its variant 6 (CD44v6) in normal and neoplastic lung tissue and correlate it with prognostic factors in lung cancer. Methods: The study included 52 non-small cell lung carcinomas (NSCLC) (21 squamous cell carcinomas and 31 adenocarcinomas), 15 small cell lung carcinomas (SCLC) and 8 carcinoid tumors. Expression of CD44s and CD44v6 was evaluated by immunohistochemistry and correlated with lung cancer prognostic factors. Results: All squamous cell carcinomas expressed both CD44s and CD44v6. Adenocarcinomas expressed CD44s in 39% of cases and CD44v6 in 45%. Carcinoid tumors expressed only CD44s in 88% of cases. All SCLCs were negative for both CD44s and CD44v6. A restricted panel consisting of CD44s and CD44v6 will discriminate NSCLC from SCLC with a sensitivity of 67% and a specificity of 100%. In adenocarcinoma CD44s expression was significantly correlated with lymph node metastases (p=0.007) while CD44v6 expression was more significantly associated with tumor size (p=0.0032). Conclusions: CD44s and CD44v6 are expressed in certain types of lung cancer. In adenocarcinoma CD44s and CD44v6 expression is significantly correlated with lymph node metastases and tumor size.