Peripheral squamous cell carcinoma is a type of non-small cell lung cancer (NSCLC) in which a better prognosis for patients is often directly related to lower levels of squamous cell carcinoma antigen in the blood. Lung cancer is one of the common cancers that cause death in humans, and squamous cell carcinoma (SCC) can account for 20% to 30% of NSCLC; based on the locus of origin, SCC can be subdivided into central squamous cell carcinoma (c-SCC) and peripheral squamous cell carcinoma (p-SCC), and when c-SCC is predominantly prevalent, the incidence of p-SCC is increased, and its clinical and biologic behaviors are are currently unknown. In a recent research paper published in the international journal the Journal of Thoracic Oncology, researchers from Keio University School of Medicine and other locations in Japan evaluated 280 patients who had peripheral squamous cell carcinoma removed surgically for clinical and pathologic alterations that were used to identify potential prognostic factors in the patients. In the article, the researchers revealed that low preoperative serum levels of squamous cell carcinoma antigen or absence of tumor invasion into the pleura were independent prognostic factors for patients with peripheral squamous cell carcinoma at any stage, who tended to have longer survival when the disease did not recur, as well as for a subpopulation of patients with early stage 1 disease. The study revealed that peripheral squamous cell carcinoma patients with higher serum levels of lung squamous cell carcinoma antigen were more likely to recur than individuals with lower serum levels of lung squamous cell carcinoma antigen, and that pleural and vascular invasion is a key step in the progression and metastasis of peripheral squamous cell carcinoma. In conclusion, the investigators note that clinical trials must be conducted to assess whether postoperative chemotherapy will have a significant benefit in patients whose disease is at an early stage and who do not receive chemotherapy.