Chemotherapy for advanced non-small cell lung cancer with a focus on squamous cell carcinoma

Lung cancers are broadly divided into small-cell lung cancer (SCLC) and non-SCLC (NSCLC), and the treatments for each differ. NSCLC includes squamous cell carcinoma, adenocarcinoma, large cell carcinoma, and others. However, because there is little difference in treatment efficacy between these histological types, they have collectively been treated as a single entity. Cytotoxic anti-cancer agents, mainly platinum-based drugs, are the first-line treatment for unresectable advanced NSCLC, and the standard therapy is combination chemotherapy with two drugs, usually involving one platinum-based and one unrelated cytotoxic drug. Such regimens have been used for all the different histological types. In recent years, however, genetic abnormalities in NSCLCs known as driver mutations have been identified. These include epidermal growth factor receptor mutations and anaplastic lymphoma kinase translocations, which are responsible for both carcinogenesis and cancer growth and survival. The advent of molecular targeted therapies that target these mutations has clearly improved the prognosis for NSCLC. However, effective molecular targeted drugs or novel anti-cancer agents that greatly prolong survival have not yet been developed to treat squamous cell carcinoma or 30% of adenocarcinomas. For patients with these types of cancers, it is important to use existing cytotoxic anti-cancer agents appropriately in their treatment. In this paper, we review the treatment options for unresectable advanced NSCLC on the basis of recent findings, with a particular focus on squamous cell carcinoma, for which groundbreaking drugs have yet to be discovered.