The PSA (prostate-specific antigen) test is a blood test used for routine prostate cancer screening. The "PSA bounce" is a rise and then decline in the PSA level following radiation treatment for prostate cancer. The bounce phenomenon occurs in a third to half of men treated with radiation for prostate cancer. Urologists, radiation and medical oncologists have struggled with what a bouncing PSA means for a patient's prognosis, and how or if to offer further treatment.
"Because a steady rise in PSA can mean that cancer has recurred, physicians often interpret a bounce as the possibility that the cancer may still exist after treatment," explained Eric M. Horwitz, M.D., clinical director of the radiation oncology department at Fox Chase Cancer Center and lead author of the study. "Some physicians prescribe hormonal therapy in this situation, but hormones can have significant side effects for the patient, and may not be clinically necessary. For these reasons, it's important to develop clear guidelines."
In this retrospective analysis, data were gathered from the records of 4,839 men treated only with external-beam radiation between 1986 and 1995 at nine institutions throughout the US. The median follow-up was 6.3 years. Treatment during this time period consisted primarily of conventional radiation therapy, a lower dose than is generally used at academic cancer centers today, although some patients were treated with 3D conformal radiation therapy. In this study, 978 patients experienced at least one post-treatment PSA bounce.
"What our study shows is that younger men have a PSA bounce more often than older patients, and patients with an increased risk of disease recurrence also bounce more often. This translates into lower PSA control," said Horwitz. "But our analysis also shows that without additional treatment, including hormones, these men live as long as those who don't experience a PSA bounce."
"Because this is a large study, it provides solid evidence that a PSA bounce may not automatically dictate hormone intervention. Ideally, this study should be conducted with more modern radiation therapy techniques, including higher doses, to confirm these findings," Horwitz concluded.
Fox Chase Cancer Center was founded in 1904 in Philadelphia, Pa. as the nation's first cancer hospital. In 1974, Fox Chase became one of the first institutions designated as a National Cancer Institute Comprehensive Cancer Center. Fox Chase conducts basic, clinical, population and translational research; programs of prevention, detection and treatment of cancer; and community outreach. For more information about Fox Chase activities, visit the Center's web site at www.fccc.edu or call 1-888-FOX CHASE.