Serum amino acid levels as a biomarker for renal cell carcinoma

Purpose: Prognosis in renal cell carcinoma is dependent on tumor stage at presentation, with significant differences in survival between early and late stage disease. Currently to our knowledge no screening tests or biomarkers have been identified for the early detection of kidney cancer. Therefore, we investigated whether serum amino acid profiles are a potentially useful biomarker in patients with renal cell carcinoma. Materials and Methods: The concentrations of 26 amino acids were determined in serum taken preoperatively from 189 patients with renal cell carcinoma, and from 104 age and sex matched controls. Results: Statistically significant changes were observed in patient levels of 15 amino acids, with 13 being decreased and 2 being increased. A logistic regression model using 8 amino acids including cysteine, ornithine, histidine, leucine, tyrosine, proline, valine and lysine was created to distinguish cases from controls. A receiver operator curve based on this model had an area under the curve of 0.81. This same model also had predictive value in terms of overall survival and tumor recurrence in patients with renal cell carcinoma. Conclusions: Our findings suggest that serum amino acid levels may be useful as a screening tool for the identification of individuals with renal cell carcinoma and the prediction of outcomes.