Prognostic factors in renal cell carcinoma: Association of preoperative sodium concentration with survival

Purpose: Conventional renal cell carcinoma (RCC) has a variable natural history, and determining individual prognosis is important to guide management. We have examined the prognostic significance of a large number of hematologic and biochemical variables, as well as traditional tumor-related factors in patients with RCC. Experimental Design: Patients undergoing nephrectomy for newly diagnosed RCC between September 1998 and March 2005 were invited to participate. Clinical, pathologic, and laboratory data were recorded in each case, and immunophenotyping was carried out on a subset of patients. A planned subset analysis of patients presenting with N0M0 disease was done. Results: Two hundred twelve patients with RCC formed the study population. In addition to tumor-related factors, multivariate analyses revealed preoperative serum sodium concentration to be independently and significantly associated with overall survival and disease-free survival when considered as both a continuous variable and when dichotomized to above and below the median value [139 mmol/L; reference range 135-145 mmol/L, hazard ratio 0.44, 95% confidence interval (95% CI) 0.22-0.88, P = 0.014]. Five-year overall survival estimates for patients above and below the median serum sodium were 67.6% (95% CI 54.2-80.9) and 44.3% (95% Cl 32.8-55.8), respectively. These findings persisted in the N0M0 subgroup analysis. Conclusions: We have confirmed the prognostic value of traditional tumor-related factors but, to our knowledge, these are the first data to show that low preoperative sodium concentration may be an important factor associated with reduced survival in patients with RCC, suggesting that serum sodium should be considered with established prognostic variables in modeling survival in RCC.