Proteinuria: Associated with poor outcome in patients with small cell lung cancer

Objective: Although proteinuria has been increasingly reported in lung cancers, especially small cell lung cancer (SCLC), its clinical impact in patients with SCLC remains unknown. Materials and Methods: We analyzed patients with newly-diagnosed SCLC confirmed by clinical, radiological, and pathological features over a 7-year period. Pretreatment proteinuria was assessed by quantitative analysis of 24-h urine before receiving chemotherapy. The demographic, laboratory characteristics and its impact on survival outcome were evaluated. Results: There were 140 SCLC patients with the mean age of 70.2 years, extensive stage (89.3%), and male predominance (81.4%). Significant proteinuria (>300 mg/day) occurred in 17.4% (24/140) patients. Patients with proteinuria had significant higher serum blood urea nitrogen, lower total calcium, total protein, albumin levels, and lower creatinine clearance (Ccr) (24-h Ccr). Daily protein excretion was negatively correlated with serum total protein, albumin, and Ccr. Using a multivariable Cox proportional hazard model, proteinuria (hazard ratio, 1.943, 95% confidence interval 1.148–3.259, P = 0.010), along with poor performance status and serum albumin, were independent risk factors of all-cause mortality. Proteinuria was also associated with poor survival status (6.08 vs. 11.88 months, P 2 g/day). Conclusions: Proteinuria is not uncommon and associated with all-cause mortality in patients with SCLC.