We also established a gene interaction network based on the most significantly associated survival genes in LUSC (P < 0.01), and several hub genes were identified, such as SMAD4 and FOS. SMAD4 gene is a tumor suppressor gene, and its mutations have been found in a variety of cancers, such as pancreatic cancer, colorectal cancer and lung cancer. Here, SMAD4 is linked to lung cancer.