Protein profiling of non-malignant and malignant ascites by SELDI-TOF MS: proof of principle

Ascites is a common clinical symptom in liver cirrhosis, inflammatory disorders of the abdomen and a major late manifestation of metastatic malignancies. Standard cytopathological techniques and immunocytochemistry have specificities and sensitivities of approximately 95 and 60%, respectively for the presence of tumor cells. Development of faster and more accurate screening methods would be of great clinical utility. In this work we examined differential analysis of the unbound proteins in the supernatant of ascites fluid by Protein-Chip SELDI mass spectrometry. There were 21 tumor cell-positive and 34 tumor cell-negative samples. We used principal component analysis coupled with linear regression applied to the mass spectra of the samples to distinguish between the sample groups. Two sample sets for statistical analysis were created after randomization, a training set with 37 samples and a validation set with 18 samples resulting in a specificity of 93% and a sensitivity of 83% on the training set. The validation set yielded a specificity and sensitivity of 75%. This study suggests that SELDI-TOF mass spectrometry appears to have great potential as a surrogate diagnostic tool to evaluate effusion specimens.