A quantitative model for the dynamics of serum prostate-specific antigen as a marker for cancerous growth - An explanation for a medical anomaly

Prostate-specific antigen (PSA) is an enzyme produced by both normal and ca ncerous prostate epithelial cells. Although PSA is the most widely used ser um marker to detect and follow patients with prostatic adenocarcinoma, ther e are certain anomalies in the values of serum levels of PSA that are not u nderstood. We developed a mathematical model for the dynamics of serum leve ls of PSA as a function of the tumor volume. Our model results show good ag reement with experimental observations and provide an explanation for the e xistence of significant prostatic tumor mass despite a low-serum PSA. This result can be very useful in enhancing the use of serum PSA levels as a mar ker for cancer growth.