Clinical significance of FAP-α on microvessel and lymphatic vessel density in lung squamous cell carcinoma

Aims We aimed to determine whether cancer-associated fibroblasts (CAFs) are associated with microvessel density (MVD) and lymphatic vessel density (LVD) in lung squamous cell carcinoma, as well as their clinical significance in predicting survival. Methods 122 patients were enrolled in the study. Samples were obtained on resection at the Department of Thoracic Surgery of the Qingdao Municipal Hospital between January 2011 and December 2014. Immunohistochemistry was used to determine vessel and lymphatic vessel density, and CAF abundance (fibroblast activation protein alpha (FAP-alpha) positivity). Statistical analyses were performed on 85 patients to test for correlation of CAF density and other clinicopathological variables with 3-year overall survival (OS) and disease-free survival (DFS). Results High stromal CAF abundance significantly correlated with increased MVD and LVD in lung squamous cell carcinoma (p<0.05). chi(2) test revealed a significant association of CAF density with lymph node metastasis. Cox proportional hazards model showed that both higher CAF density and lymph node metastasis negatively correlate with survival. CAF density or lymph node status can be used as an independent prognostic factor to predict 3-year OS and DFS. Conclusions CAF density, identified by FAP-alpha staining pattern, should be considered as a novel biomarker for disease prognosis in patients with lung squamous cell carcinoma.