The predictive and prognostic values of serum amino acid levels for clear cell renal cell carcinoma.

OBJECTIVES: To investigate the predictive and prognostic values of the logistic regression model based on the serum amino acid levels.

MATERIALS AND METHODS: The study enrolled 42 patients with clear cell renal cell carcinoma (ccRCC) and 66 matched healthy people admitted to PLA General Hospital from April 2015 to June 2015. Serum samples from the 2 groups were analyzed by isobaric tags for relative and absolute quantitation-liquid chromatography-tandem mass spectrometry (iTRAQ-LC-MS/MS) method. Variables of the 2 groups were compared by Student's t-test or chi-square test. The prediction model was constructed by logistic regression analysis. Oncological outcomes were evaluated by Kaplan-Meier survival analysis and Cox regression analysis.

RESULTS: Pathological diagnosis confirmed that all patients had ccRCC. No significant differences were found in the distribution of age, sex, or body mass index between patients with ccRCC and matched healthy people. A total of 32 amino acids were quantitatively analyzed, and serum levels of 23 amino acids were significantly different between the 2 groups. A predictive logistic regression model containing histidine, glutamine, 1-methyl histidine, and norvaline was constructed. Receiver operating characteristic (ROC) curves for all patients with ccRCC and controls, patients with T1 ccRCC and controls, patients with Fuhrman grade 1 to 2 ccRCC and controls, patients with T2 ccRCC and controls, and patients with Fuhrman grade 3 ccRCC and controls were drawn based on the model. The area under the curve values of the 5 receiver operating characteristic curves were 0.878, 0.885, 0.890, 0.830, and 0.788, respectively. Patients with higher model scores (>2) had significantly poorer progression-free survival (PFS) than patients with lower model scores (≤2). Multivariable Cox regression analysis showed that logistic regression model score was an independent predictor of PFS.

CONCLUSION: Serum amino acid levels are a potential predictive biomarker for distinguishing patients with ccRCC, especially early T-stage and low Fuhrman grade patients, from healthy people. Serum amino acid levels can also be used in the prognostic evaluation of patients with ccRCC.