Probability of False Prostate Cancer Diagnosis Using a Logistic Function Given Age and f/t PSA Ratio
Prostate specific antigen (PSA) is a protein of free and complex forms found in the bloodstream of patients suffering from prostatic diseases. The free/total PSA ratio is often used in the detection of prostate cancer. We define a logistic function that assigns the probability of having cancer given a specific value of the f/t PSA ratio and the age of the patient. Since the levels of PSA in a serum sample are affected by storage conditions over time, we construct a model to show the effect of improper storage of serum samples on the f/t PSA readings. We then use the logistic function and the model of sample decay over time to determine the probability of a false positive given the storage conditions. In addition we provide an analysis of cut-off values, and a function that predicts the time necessary for the diagnosis of a patient to change from negative to positive given his age, f/t PSA Ratio, and a cut-off value.
- Poster session award recipient at the 1999 National SACNAS Convention in Portland, OR
- Poster session award recipient at the 2000 AMS/MAA Joint Mathematics Meeting in Washington DC
Aldo Crossa, Wittenberg University
Johnny Guzmán, California State University, Long Beach
Andie Hodge, University of the Virgin Islands
Brisa N. Sánchez, University of Texas, El Paso