The Phenomenon of PSA Bounce After Radiation Therapy
Following radiotherapy for prostate cancer, the serum PSA level will fall to reach a nadir several years later. PSA bounce refers to a benign intermittent PSA rise prior to subsequent decrease. It has been observed in all forms of primary radiotherapy str
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Peter Acher and Rick Popert
Prostate-specific antigen (PSA) is a 34-kDa serine protease secreted by prostate epithelial cells; it has a role in the liquefaction of semen. Low concentrations of PSA are found in the normal sera where it is exploited as a tumor marker. Following radical prostatectomy, serum PSA levels are expected to fall to undetectable levels within a few weeks, and subsequent detection of PSA signifies biochemical recurrence. The effects of radiotherapy treatments, however, depend on DNA damage and only become apparent during postmitotic events that may take several generations. Thus, the serum PSA level will fall slowly to reach a nadir often 3 years later [1]. During this time, the serum PSA value may rise before resuming its decrease without any therapeutic intervention – this is the phenomenon known as “PSA bounce”, also known as PSA “bump” or “spike” [2]. Although it is a benign occurrence, it is a source of anxiety for patients and physicians alike since it may easily become confused with a persistently rising PSA that denotes recurrent disease that requires treatment. Kent Wallner first described the bounce phenomenon (“spike”) in the context of patients treated with combination interstitial brachytherapy and external beam radiation [2]. Since then, it has since been observed in all groups of primary radiotherapy patients with or without hormonal treatments (there are no data concerning salvage or metastatic therapies). With respect to external beam radiotherapy (EBRT), PSA bounce has been reported in series of conventional EBRT, 3-D conformal radiotherapy, intensity-modulated radiotherapy (IMRT), and more recently stereotactic body radiotherapy [3–7]. The incidence following EBRT alone ranges from P. Acher, M.A., FRCS (Urol), Ph.D. (*) Department of Urology, Southend University Hospital NHS Foundation Trust, Prittlewell Chase, Westcliff-on-Sea, Essex SS0 0RY, UK e-mail: [email protected] R. Popert, M.S., FRCS (Urol) Department of Urology, Urology Centre, Guy’s and St. Thomas’ Hospitals, 1st Floor Southwark Wing, Guy’s Hospital, St. Thomas’ Street, London SE1 9RT, UK e-mail: [email protected] A. Tewari (ed.), Prostate Cancer: A Comprehensive Perspective, DOI 10.1007/978-1-4471-2864-9_68, © Springer-Verlag London 2013
12 to 66 % depending on the definition of bounce used, i.e., the value of the PSA rise and fall, for example, defined by Rosser et al. as ³0.5 ng/mL with a decrease to pre-bounce levels and by Pickles et al. as any increase followed by any decrease [4, 8]. The average time to bounce in these series ranged from 9 to 35 months [4, 5]. In a recent report on IMRT, one bounce occurred at 87 months posttreatment [7]. In the largest (multi-institutional) analysis of 4,839 patients treated with EBRT alone, 20 % of patients experienced bounce defined as an increase of ³0.4 ng/mL over 6 months followed by any decrease [6]. One quarter of these patients experienced multiple bounces. Pickles et al. reported on nearly 2,000 men treated with EBRT at British Colombia Cancer Ag
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