Rise in PSA May Predict Death from Prostate Cancer
In research presented at the 51st annual meeting of the American Society for Radiation Oncology (ASTRO) in Chicago, men diagnosed with prostate cancer who experience a rise in their PSA within 18 months of undergoing radiation therapy are more likely to die of the disease.
PSA stands for prostate-specific antigen, and is a protein made by the prostate gland. PSA levels may be higher than normal in men with prostate cancer, benign prostatic hyperplasia (BPH), or infection of the prostate gland. The PSA test measures the amount of the antigen found in the blood. Levels under 4 ng/mL are considered normal; results over 10 ng/mL are high.
Fox Chase Cancer Center radiation oncologist, Mark Buyyounouski MD, led the study of 2,132 men with clinically localized prostate cancer that suffered biochemical failure after treatment. Biochemical failure was defined as the patient’s lowest PSA level plus 2.
19% of patients developed failure at 18 months or less. The five-year cancer survival rate for these men was 69.5%, compared with 89.8% for men who developed biochemical failure after 18 months. An analysis of the results showed that the interval to failure had a better predictive value for cancer-specific mortality than other variables, including Gleason score (a test that predicts the aggressiveness of the disease), tumor stage, age and PSA doubling time.
"PSA is the gold standard for following prostate cancer patients after they receive radiation or surgery. But we haven't known if having PSA rise sooner means a patient has a greater danger of dying of prostate cancer, though it seems logical," Dr. Buyyounouski says.
Currently, most physicians do not start treatment based on biochemical failure alone, but rather wait until the PSA reaches a high level or there is some other evidence that the tumor has spread. "The potential impact of this finding is that patients can initiate treatment far sooner without waiting for other signs or symptoms of prostate cancer," said Buyyounouski. "If a patient has biochemical failure at 16 months, rather than wait and learn later that the PSA is rising sharply and risk the development of distant metastasis, therapy can be started sooner based on the increased risk of death."
The National Cancer Institute estimates that over 190,000 new cases of prostate cancer has occurred so far in 2009. 27,360 men have died from the disease. The American Cancer Society recommends that men begin to get annual PSA screenings beginning at age 50.
Additional sources included: Fox Chase Cancer Center, National Cancer Institute, American Cancer Society, and Prostate Cancer Foundation.