Biomarkers in the lung cancer diagnosis: a clinical perspective

The propensity for tumor biomarkers to be detected in serum at an early disease stage has become an area of interest for clinicians. This study aimed to evaluate the efficiency of 7 tumor biomarkers, namely, carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), cytokeratin 19 (CYFRA-21-1), alpha-fetoprotein, carbohydrate antigen-125 (CA-125), carbohydrate antigen-19.9 (CA-19.9), and ferritin, independently or in combination for the diagnosis of lung cancer. Electrochemiluminescence immunization was used to determine biomarker levels expressed in 530 patients with pulmonary disease and 229 healthy subjects. The observed levels of CEA, NSE, CYFRA-21-1, CA-125, and CA-19.9 in patients with pathologically confirmed lung cancer were significantly higher than those in patients with benign pulmonary disease or control subjects. Adenocarcinoma, squamous cell carcinoma, and small cell carcinoma of the lung were associated with the highest observed levels of CA-125, CYFRA-21-1, and NSE, respectively. Combining biomarkers successfully led to the diagnosis of lung cancer. CEA + NSE + CA-125 showed the highest sensitivity for small cell carcinoma, at 83.33%, whereas CEA + NSE + CYFRA-21-1 + CA-125 showed 94.11% sensitivity for squamous cell carcinoma. The combination of 6 biomarkers, namely, CEA + NSE + CYFRA-21-1 + CA-125 + ferritin + CA-19.9, showed 80.49% sensitivity for adenocarcinoma. Combining biomarkers significantly aided in the diagnosis of lung cancer. However, this increased sensitivity on combination was accompanied by a decreased specificity for lung cancer subtypes. Combining biomarkers appropriately increases their sensitivity and helps with the diagnosis of lung cancer.