Raised serum urea predicts for early death in small cell lung cancer

Previous studies have defined prognostic factors predicting a favourable response to treatment and long-term survival in small cell lung cancer (SCLC) patients. Here we sought specific pre-treatment features predicting early death in SCLC.

An exploratory cohort of 62 patients with poor prognosis SCLC and a separate confirmatory independent cohort of 152 unselected SCLC patients were identified to determine risk factors for early death, defined as within 8 weeks of diagnosis.

In an exploratory cohort of patients with poor prognosis SCLC, 46 received chemotherapy and 16 patients received no chemotherapy. Multivariate analysis of chemotherapy patients showed a raised serum urea to be predictive of early death - increasing the risk by 13-fold (odds ratio 13.3, 95% confidence interval=2.8-64). In a separate cohort of 152 unselected SCLC patients, 123 received chemotherapy and 29 did not. Logistic regression analysis of treated patients showed that performance status >2 (P=0.009), urea>upper limit of normal (P=0.01), neutrophil count >10 (P=0.024) and weight loss >10% (P=0.03) significantly contributed to the risk of early death. Of note, raised serum urea increased the risk of early death by 12-fold (odds ratio 11.8, 95% confidence interval=1.8-76.9).

We have shown that pre-treatment raised serum urea is a significant predictor of early death. This readily available information will be useful for assessing SCLC patients at the bedside and discussing the risks of chemotherapy with them.