August 19 (HealthDay News) -- A mathematical model to find blood biomarkers that can help doctors estimate the size of cancer tumors has been developed by researchers at Stanford University.

The team says its work may help guide development of new tests to improve early detection of cancer. Currently, there's no reliable method of using the results of blood-screening tests to gauge tumor size.

The Stanford researchers developed their mathematical model using two common blood biomarkers: prostate specific antigen (PSA), which is often elevated in prostate cancer, and CA125, used as a marker for follow-up therapy in ovarian cancer patients.

Using this model, the researchers found that the minimum tumor sizes predicted by their calculations were close to what was actually seen in clinical practice.

"We're pretty happy that we came up with rather realistic tumor sizes. Although this is a very basic model, it should give researchers a tool to use when deciding if a particular secreted protein would be a good biomarker," radiologist Dr. Amelie Lutz said in a Stanford news release.

"Early cancer detection is a very challenging but important goal for the cancer field. This modeling work enables a very deep understanding of the problems that will have to be solved for blood-based cancer biomarkers to be successful in this effort," study senior author Dr. Sanjiv Sam Gambhir, a professor of radiology, said in the news release.

The study was published in the Aug. 18 issue of the journal PLoS Medicine.

SOURCE: Stanford University, news release, Aug. 18, 2008