Background: Pulmonary peripheral-type squamous cell carcinoma (p-SqCC) has been increasing in incidence. However, little is known about the clinicopathologic features of p-SqCC. This study aimed to investigate the clinicopathologic characteristics and clinical outcomes of p-SqCC compared with central-type SqCC (c-SqCC) in a large cohort of surgically resected lung SqCC patients with long-term follow-up results.
Methods: The study included 268 patients with SqCC who underwent surgical resection at the authors' institute from January 1990 to September 2013. The mean follow-up period was 67.1 months. The clinicopathologic and genetic characteristics were investigated in relation to their association with progression-free survival (PFS) and overall survival (OS) based on tumor location.
Results: The study cohort included 120 patients with p-SqCC and 148 patients with c-SqCC. Compared with c-SqCC, p-SqCC was correlated with older age (p = 0.002), female sex (p = 0.033), better performance status (p < 0.001), smaller tumor (p = 0.004), less lymph node metastasis (p < 0.001), and an earlier pathologic stage (p < 0.001). Despite the clinicopathologic differences, tumor location was not significantly correlated with clinical outcomes. For the p-SqCC patients, the multivariate analysis showed a significant correlation of lymphovascular invasion (PFS, p < 0.001; OS, p < 0.001) and lymph node metastasis (p = 0.007; OS, p = 0.022) with poor PFS and OS, but a significant correlation of incomplete tumor resection (PFS, p = 0.009) only with poor PFS.
Conclusions: The clinicopathologic features differed between the p-SqCC and c-SqCC patients. Lymphovascular invasion and lymph node metastasis were independent prognostic factors of p-SqCC. These prognostic factors may be potentially used as indicators for adjuvant therapies to be used with patients who have p-SqCC.