TennesseeSince the advent of the new proteomics era more than a decade ago, large-scale studies of protein profiling have been exploited to identify the distinctive molecular signatures in a wide array of biological systems spanning areas of basic biological research, various disease states, and biomarker discovery directed toward therapeutic applications. Recent advances in protein separation and identification techniques have significantly improved proteomics approaches, leading to enhancement of the depth and breadth of proteome coverage. Proteomic signatures specific for invasive lung cancer and preinvasive lesions have begun to emerge. In this review we provide a critical assessment of the state of recent advances in proteomic approaches and the biological lessons they have yielded, with specific emphasis on the discovery of biomarker signatures for the early detection of lung cancer.Keywords: proteomics; biomarker; early detection; lung cancer
CHALLENGES IN LUNG CANCER RESEARCHLung cancer is the deadliest cancer in the United States and worldwide, accounting for 15% of all cancer incidence and 29% of all cancer deaths, with a 5-year survival rate of only 15% (1, 2). Lung cancer represents a spectrum of diseases with tremendous heterogeneity at the pathological and molecular levels (3-6) that is strongly associated with smoking as a risk factor. With about 20% of the United States adult population smoking and 1 billion smokers worldwide, it was estimated that in 2009 lung cancer claimed more lives than breast, prostate, colon, liver, kidney, and melanoma cancers combined (2, 7). Despite the recent improvements of bronchoscopic and surgical techniques as well as advances in chemotherapy and radiation therapy treatments, attempts to improve patient outcomes are faced with immense challenges. Several noninvasive detection technologies have been investigated. Imaging techniques, such as chest radiography, lowdose spiral computed tomography, sputum cytology, and molecular biomarkers in various biological samples, have been tested for their diagnostic value for early detection of lung cancer (8, 9). Although these tests vary in their sensitivity and specificity, only low-dose chest computed tomography was shown to reduce lung cancer-specific mortality (10-12). This encouraging finding calls for new molecular strategies to address the noninvasive diagnostic and risk assessment for lung cancer. These molecular strategies will have to demonstrate clinical utility and may complement currently tested strategies.
NATURAL HISTORY OF LUNG CANCER PROGRESSION AND A WINDOW FOR EARLY DETECTIONLung cancer can be considered to result from a long history of repeated airway damage and repair cycles. Although clinically addressed at the time of diagnosis, the disease process develops for months and years before affecting patients' lives. This rather long disease process (Figure 1) represents a window of opportunity where the intervention should take place with the aim of preventing the development of disease (e.g., primary preven...