1. A method comprising: tabulating histogram data of malignant and benign nodules as a function of biomarker values for a specified patient population suspect of having a specific type of cancer, where biomarker values comprise mean image data values; separating tabulated histogram data into a plurality of biomarker bins where the bins are ranges of biomarker values; calculating malignancy probability fractions for each biomarker bin by dividing a number of true positives in each marker bin by a summed number of true and false positives in each biomarker bin; scanning a suspect nodule in a patient, and determining a characteristic biomarker value for the suspect nodule; and determining from the tabulated histogram data, the malignancy probability for the suspect nodule.