External Beam Radiation (EBR)
The PSA bounce after radiation for prostate cancer
Researchers look at whether the bounce affects patients' overall survival
ASTRO, Atlanta /PSA Rising/ October 5, 2004 — Using the largest known prostate cancer data set of patients treated solely with external-beam radiation in the U.S., radiation oncologists have examined the "PSA bounce" and determined that it is not an indicator that men will die of prostate cancer any sooner than those men who do not experience a bounce.
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," Horowitz said, "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 a retrospective analysis presented at the ASTRO meeting in Atlanta, GA, data were gathered from the records of 4,839 men treated only with external-beam radiation between 1986 and 1995 at nine cancer centers 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 major 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.
PSA bounce more likely to occur after brachytherapy than after external beam radiation:
A recent Canadian study reports that "The bounce rate ... was 58% with EBRT and 84% with brachytherapy." Prostate-specific antigen (PSA) bounce and other fluctuations: which biochemical relapse definition is least prone to PSA false calls? Pickles T; British Columbia Cancer Agency Prostate Cohort Outcomes Initiative. Int J Radiat Oncol Biol Phys. 2006 Apr 1
More than one explanation for why it happens:
Frank A. Critz, M.D., medical director at Radiotherapy Clinics of Georgia in Decatur and lead author of a study that appeared in the April 2000 issue of the Journal of Urology, says the bounce "is thought to be due to inflammation of the prostate, a condition that causes PSA levels to rise independently of any possible cancer. Men who undergo brachytherapy and have a bounce also experience symptoms of an inflamed prostate, such as a burning sensation during urination." A PSA "Bounce" Probably Doesn't Mean Recurrence of Prostate Cancer. Kevin K. Singer April 14, 2000
Louis Pisters, MD, of the MD Anderson Cancer Center in Houston, says the bounce in PSA may be caused "by death of damaged cancer cells that then release their PSA. " (ACS: PSA Bounce No Reason for Concern, 2002/12/03).
Time of PSA rise helps differentiate between "bounce" and biochemical failure:
A Cleveland Clinic team reports that for brachytherapy patients, "The time of the PSA rise after nadir occurs far sooner for a PSA bounce than for bF [biochemical failure]. This factor should be considered when assessing a patient with a rising PSA level after PI before a patient is administered salvage therapy. " PSA kinetics after prostate brachytherapy: PSA bounce phenomenon and its implications for PSA doubling time. Klein EA, et al. Department of Radiation Oncology, Cleveland Clinic Foundation, Cleveland, OH 44195, USA. Int J Radiat Oncol Biol Phys. 2006 Feb
Bounce as a good prognostic indicator:
The Cleveland Clinic team reported earlier that "A PSA bounce may be associated with improved biochemical relapse-free survival."
"Immediate salvage therapy in patients with a rising PSA level after permanent prostate brachytherapy should not be initiated provided the PSA increase does not exceed the pretreatment PSA value."
For more information about Fox Chase activities, visit the Center's web site at www.fccc.edu or call 1-888-FOX CHASE.
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