Routine prostate cancer screening reduces metastasis risk

Men treated for prostate cancer who were diagnosed after the start of routine screening had a significantly reduced risk of the disease spreading to other parts of the body (metastases) within 10 years of treatment, compared to men who were treated prior to the use of routine screening, according to the first study-of-its-kind presented November 1, 2010, at the 52nd Annual Meeting of the American Society for Radiation Oncology (ASTRO).

In 1993, routine prostate cancer screening became widely implemented through the use of a prostate specific antigen (PSA) test that was able to catch and diagnose the disease earlier. The test measures the level of prostate specific antigen, a protein produced by the prostate that can be measured through a simple blood test. Increased levels of PSA may be a sign of prostate cancer.

Opponents of routine screening have argued that routine prostate cancer screening has not resulted in a meaningful improvement in survival. However, researchers in this study considered that the best way to measure the screening's effectiveness may be to examine its ability to decrease metastatic prostate cancer within 10 years after treatment for a screened population.

"Our study shows that routine screening not only improves the patient's quality of life by stopping metastatic disease, but it also decreases the burden of care for this advanced disease that must be provided by the health care system," Chandana Reddy, M.S., lead author of the study and a senior biostatistician at the Cleveland Clinic in Cleveland, said. "This demonstrates that the PSA test is extremely valuable in catching the disease earlier and allowing men to live more productive lives after treatment."

Metastatic prostate cancer is when the cancer has spread beyond the prostate and surrounding area to other places in the body. This advanced stage of the disease is not curable.

The retrospective study was based on data from 1,721 prostate cancer patients who were treated with either radiation therapy or surgery to remove the prostate gland and surrounding tissue at the Cleveland Clinic between 1986 and 1996. To assess the impact of screening, the patients were divided into two groups according to when they were treated: a prescreening era (1986-1992) or a post-screening era (1993-1996). Patients were also classified as having high-, intermediate- or low-risk disease to determine which groups may have benefitted from prostate cancer screening.

The study shows that within each of the three risk groups, patients treated in the prescreening era were significantly more likely to develop metastatic disease within 10 years of treatment, compared to men in the post-screening era.