Levels of serum bilirubin in small cell lung cancer and non-small cell lung cancer patients

Elevated bilirubin has been associated with protection of cardiovascular and kidney systems, whereas decreased bilirubin may predispose respiratory diseases. However, whether serum bilirubin levels are associated with lung cancer remains unclear. Here, clinical and pathologic data of a cohort of 363 lung cancer patients along with 363 age-and gender-matched healthy subjects were collected. The association of serum bilirubin levels with lung cancer was analyzed. The levels of serum bilirubin were significantly lower in lung cancer patients. The aspartate transaminase and alkaline phosphatase levels were significantly higher in lung cancer. Multi-classification logistics regression analysis revealed low total bilirubin level [OR (95%CI), 1.12 (1.02-1.23)], aspartate transaminase [OR (95%CI), 1.12 (1.02-1.23)], and alanine transaminase [OR (95%CI), 1.12 (1.02-1.23)] were risk factors in lung cancer. Serum bilirubin levels were significantly changed among small cell lung cancer (SCLC), lung adenocarcinoma (LAC) and lung squamous cell carcinoma (LSC). Total bilirubin level, smoke history and heart disease were risk factors for subtypes. Compared with LSC, patients with smoke history had significant higher risk in LAC [OR (95% Confidence Interval, CI), 4.49 (1.70, 11.96)]. Compared with LSC, patients with smoke history [OR (95%CI), 4.49 (1.70, 11.96)] and heart disease [OR (95%CI), 4.49 (1.70, 11.96)] had significant higher risk in SCLC. Compared with SCLC, patients with low total bilirubin [OR (95%CI), 1.12 (1.02-1.23)] and heart disease [OR (95%CI), 3.52 (1.01-12.23)] had significant higher risk in LAC. Taken together, these results suggested low serum bilirubin levels are tightly associated with lung cancer, especially with LAC. Serum bilirubin levels might serve as a predictor for lung cancer patients clinically.