Usefulness of Blood Biomarkers for Overall Survival in NSCLC

Lung cancer is the most common cancer type worldwide, with more than 1.1 million annual deaths. There are two types of the disease, namely non-small cell lung cancer (NSCLC) and small-cell lung cancer (SCLC), with the first accounting for 85% of the total number of cases. The 5-year survival across stages remains disappointingly low, around 10% in most countries, due to a high incidence of both loco-regional and distant failure \[3\]. However, during the last decade improved radiotherapy techniques allowed an increase of the radiation dose, while at the same time more effective chemo radiation schemes are being applied. These developments have lead to improved outcome in terms of survival. As the TNM staging system is highly inaccurate for the prediction of survival outcome for non-surgical patients, attempts have been made to develop a more accurate risk stratification for these patients \[1,2\]. A model based on clinical variables yielded an AUC of 0.74, which was encouraging, but also left room for improvement \[2\]. An extended model, which included clinical as well as biomarker variables, reached a higher AUC, but the limited number of patients included in this study made it impossible to draw definitive conclusions \[1\]. New prognostic parameters can be retrieved from several sources, which include anatomic, molecular and functional imaging, genomics, proteomics and clinical analysis of patients. The unlimited amount of information is expected to lead to more accurate predictions of individual treatment outcome \[4\]. The analysis of biomarkers, including proteins, is a fast developing, promising and challenging area of research. Biomarkers can measure or evaluate normal biological processes, pathogenic processes, or pharmacological responses to a therapeutic intervention. Oncoproteins are produced by, or in response to tumor cells, and may be secreted in the circulation of patients. As tissue sampling is often not possible in lung cancer patients, blood sa