I am comparing 4 different tests for the evaluation/identification of cancer. One is a continuous variable yielding cut-off values based on both the mean and the median of 5 consecutive measurements in the same patient. The other 3 tests are nominal tests staging the lesions from 0 (benign) - 4 (1-4 being malignant). I want to compare the resulting accuracies, sensitivities, specificities, pos/neg predictive values and likelihood ratios. I am using the SPSS package for statistical analysis. The dataset consists of 120 patients (21 with benign and 99 with malignant lesions). Any suggestions regarding how to evaluate these tests for significant differences?