Tests to Determine Severity of Cancer

Tests to Determine Severity of Cancer

PSA Levels and Velocity

Once cancer is diagnosed, PSA levels may help to determine its extent. If PSA levels are less than 20 ng/mL, it is possible that the cancer has not spread to distant sites. PSA levels over 40 ng/mL are a strong indicator that cancer has metastasized (spread throughout the body). PSA levels are also monitored after treatments begin. Changes in the level can show if a treatment is working or if the cancer has come back.

Doctors also monitor how quickly PSA levels rise over time. This rate is called PSA velocity (PSAV). The PSAV is very helpful in determining when treatment should begin and which treatment should be used. A high rate of PSAV is considered to be 2 ng/mL a year. Recent research suggests that men with early-stage prostate cancer who have a slow PSAV are more likely to live longer than men with rapidly rising PSA levels.

Biological Markers

A number of biological factors are being used or investigated as markers for cancer or its severity:

Chromosomal Sets. The number of chromosomal sets in the nucleus of the tumor's DNA, known as its ploidy, is an important marker for patients in late stages of prostate cancer. Tumors with the normal two sets of chromosomes, called diploid tumors, usually have a more favorable outcome than tumors that have four sets of chromosomes (tetraploid tumors) or have an abnormal number of individual chromosomes (aneuploid tumors).

Blood Vessel Density. The density of blood vessels in the tumor is an important indicator of outcome. The greater the density, the more likely the tumor is to be aggressive.

Serum Acid Phosphatase. High levels of this enzyme indicate a more aggressive disease and the need for intensive treatments.

Testosterone Levels. Higher total testosterone levels may increase the risk for metastasis. A 2000 study found an association with low free testosterone and more extensive prostate cancer, suggesting free testosterone could be a marker for aggressive disease. (Free testosterone, as with free PSA, is not chemically bound.)