Researchers at Wake Forest University School of Medicine and the University of Wisconsin-Madison have discovered that some elevated prostate-specific antigen (PSA) levels in men may be caused by a hormone normally occurring in the body, and are not necessarily a predictor of the need for a prostate biopsy.
Elevated levels of PSA have traditionally been seen as a potential sign of prostate cancer, leading to the widespread use of PSA testing. However, the researchers found that parathyroid hormone, a substance the body produces to regulate calcium in the blood, can elevate prostate-specific antigen (PSA) levels in healthy men who do not have prostate cancer. These "non-cancer" elevations in PSA could cause many men to be biopsied unnecessarily, which often leads to unnecessary treatment.
"PSA picks up any prostate activity, not just cancer," said lead investigator Gary G. Schwartz, Ph.D., M.P.H., an associate professor of cancer biology and epidemiology and prevention at the School of Medicine. "Inflammation and other factors can elevate PSA levels. If the levels are elevated, the man is usually sent for a biopsy. The problem is that, as men age, they often develop microscopic cancers in the prostate that are clinically insignificant. If it weren't for the biopsy, these clinically insignificant cancers, which would never develop into fatal prostate cancer, would never be seen."
However, because PSA screening has become so common, more men are being biopsied, Schwartz said. Most men, when told that they have prostate cancer, elect treatment even though it may not be necessary. In reality, Schwartz said, in only one of six cases does a biopsy diagnosis of prostate cancer result in a cancer that would be fatal if untreated.
High rates of prostate biopsy, therefore, lead to the over treatment of prostate cancer, he said, leading to an increased rate of the side effects of treatment, including impotence and urinary incontinence.
The study, coauthored by Halcyon G. Skinner, Ph.D., M.P.H., of the University of Wisconsin-Madison, appears in the current issue of Cancer Epidemiology, Biomarkers & Prevention.
For the study, the researchers analyzed data from 1,273 men who participated in the National Health and Nutrition Examination Survey 2005-2006, and who did not report any current infection or inflammation of the prostate gland, prostate biopsy in the past month, or history of prostate cancer at the time of the survey.