Growth patterns of small peripheral squamous cell carcinoma of the lung and their impacts on pathological and biological characteristics of tumor cells

Abstract

PurposeThe growth pattern of peripheral squamous cell carcinoma (SCC) of the lung is divided into two types: alveolar space-filling (ASF) growth and alveolar space-destructive (ASD) growth. The aim of this study was to investigate the clinicopathological differences between cancer cells displaying ASF and ASD growth.MethodsWe analyzed 155 patients with peripheral SCC measuring 30\xa0mm or less in diameter. The proportion of ASF in the total tumor area (%ASF) was determined using digital image analysis. We examined the clinicopathological characteristics of the cancer cells and compared the immunophenotypes of high %ASF tumors (>\u200930%) and low %ASF tumors (0%). Finally, we analyzed the prognostic impact of ASD area with small SCC cases (≤\u20092.0\xa0cm, n\u2009=\u200972).ResultsCases of high %ASF tumors showed significantly lower frequencies of lymphovascular invasion (p\u2009=\u20090.008). Immunohistochemical staining revealed that the expression score of laminin-5, invasive-related molecule, in cancer cells was significantly lower in high %ASF cases than in low %ASF cases (p\u2009=\u20090.001). Within the same tumor, laminin-5 expression in the ASF area was significantly lower than that in the ASD area (p\u2009=\u20090.001). The overall 5-year survival rate of patients with a larger ASD area (>\u20091.0\xa0cm2) was significantly lower than that of patients with a smaller ASD area (≤\u20091.0\xa0cm2) (p\u2009=\u20090.017).ConclusionsIn this study, we clearly showed that cancer cells presenting with ASF represents a “less invasive phenotype” in peripheral SCC.