Study: Prostate Cancer Test Set Too High
Lower PSA Test Level Could Detect Prostate Cancer Earlier
July 23, 2003 -- A new study suggests lowering the threshold of a test for prostate cancer -- particularly in younger men -- could help catch the disease earlier in more men. The study appears in the July 24 issue of The New England Journal of Medicine.
Prostate-specific antigen (PSA) is a protein released by the prostate gland. A PSA screening test checks for cancer by measuring the amount of prostate-specific antigen in the blood. The test is controversial because it is not a sure-fire test for just cancer. An elevated PSA test level may indicate prostate cancer or an enlargement or infection of the prostate. Because other conditions can cause a high PSA test level, a prostate biopsy is also needed to confirm if cancer is present. General guidelines show levels above 4 ng/mL require a biopsy to check for cancer.
However, at this PSA threshold level, many men with prostate cancer may be missed, the researchers say.
Lower PSA Threshold Could Save Lives
Researchers say under the current guidelines, if a PSA test level of greater than 4.1 was used to determine who underwent a biopsy, 82% of cancers in younger men and 65% of cancers in older men would be missed. They recommend lowering the threshold to 2.6 ng/mL in younger men.
To test their theory, researchers enrolled more than 6,000 men who were at least 50 years old. Some men, however, who were at high risk for prostate cancer and were at least 40 were included.
Men with prior histories of prostate cancer and biopsies or those who had a urinary tract infection or prostatitis were excluded from the study.
The results showed that lowering the PSA threshold for biopsy to 2.6 ng/mL in men younger than 60 would double the cancer-detection rate from 18% to 36%.
Early detection may increase the chance of catching prostate cancer before it spreads.
The American Cancer Society recommends prostate screening if you are a high-risk man over age 45, meaning if you are African American or have a family history of prostate cancer. Otherwise, some suggest that annual screening start at age 50.
Generally, the risks of treating prostate cancer are weighed against the benefits. Experts say that prostate cancer often grows slowly without causing any major problems. However, detecting it early and treating it could prevent some cancer-related health problems. The downside is some of the treatments can cause complications, such as the inability to control urination (incontinence) or the inability to have an erection (impotence, or erectile dysfunction).
SOURCE: The New England Journal of Medicine, July 24, 2003.