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

Although proteinuria has been increasingly reported in lung cancers, especially small cell lung cancer (SCLC), its clinical impact in patients with SCLC remains unknown.

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.

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 < 0.001), especially in those who had severe proteinuria (>2 g/day).

Proteinuria is not uncommon and associated with all-cause mortality in patients with SCLC.