IMAGING FOR RECURRENT PROSTATE CANCER - 06/09/11
Resumen |
Adenocarcinoma of the prostate is the most common malignant neoplasm and second leading cause of cancer-specific deaths among men in the United States.27 Standard curative treatment options for clinically localized disease include radical prostatectomy (RP); radiation therapy (RT) by either external-beam radiation, brachytherapy, or a combination of these; and cryosurgical ablation. Although all methods of definitive treatment have offered excellent results when disease is limited locally to the prostate, methods of conclusively determining local extent of the disease prior to treatment remain imperfect. As many as 50% of patients may be upstaged at surgery as indicated by an unforeseen spread of tumor beyond the prostatic capsule and 30% to 40% of these patients may show eventual disease progression after treatment.18
Risk of disease recurrence after RP correlates strongly with preoperative prostate-specific antigen (PSA), pathologic tumor stage, pathologic Gleason grade, and status of surgical margins.4, 13, 25 Fifty percent of patients with a preoperative PSA greater than 10 ng/mL or pathologic Gleason score greater than 7 recur within 7 years after surgery.10 Approximately 35% of patients have disease recurrence if stage T3 disease is seen pathologically, consisting of tumor outside the prostatic capsule.4 Finally, patients with positive surgical margins, independent of the tumor stage, have a 25% chance of recurrence at 5 years.19 If disease is localized at the time of RP, however, 10-year recurrence-free rates of 85% have been reported.25
Disease recurrence following RT and cryosurgical ablation has been much more difficult to characterize. This is due to the fact that the prostate is left in situ. Although most patients reach a low or undetectable nadir PSA after RT, there has been no single PSA concentration defined that determines disease recurrence. In an attempt to standardize the diagnosis of cancer recurrence, the American Society of Therapeutic Radiology and Oncology has defined recurrence following RT as three consecutive rises in serum PSA following a post-RT PSA nadir.16 The acceptable PSA following cryoablation of the prostate is also controversial.31 Unlike RT, after an initial rise in PSA secondary to PSA leak from injured cells, cryosurgery causes immediate cell death and should lead to a PSA nadir within 6 to 8 weeks.33 Accordingly, a low PSA nadir has been shown to be critical following cryosurgery to predict a successful outcome.31
A rise in serum PSA following RP, RT, or cryosurgery represents the earliest and most reliable indicator of recurrent disease.21, 29, 39 In fact, imaging for evaluation of disease recurrence does not need to be performed unless the PSA is elevated, digital rectal examination (DRE) is abnormal, or the patient has specific symptoms related to bone pain. Although PSA has become a very useful tumor marker, it alone does not differentiate local from distant disease recurrence. An elevated PSA following RT or cryosurgery may be caused by residual benign prostatic tissue, progression of tumor in the prostate, or distant disease. Although it is unlikely that a detectable or rising serum PSA following RP is the result of residual benign glands left after surgery, PSA recurrence after RT or cryosurgery can result from residual viable glands. When biochemical failure occurs following local therapy, recent evidence shows that the differentiation of local from distant failure can be accomplished reliably by the examination of specific PSA characteristics. Patients with a late biochemical recurrence (> 24 months after local treatment), low PSA velocity (change in PSA over time), and long PSA doubling time (> 6 months) most likely have recurrent local disease.29 Conversely, patients with a rapid PSA recurrence (< 24 months after local treatment), high PSA velocity, and short PSA doubling time (< 6 months) are more likely to have distant disease recurrence.29
Imaging techniques following definitive treatment for prostate cancer have become critical as a clinical adjunct along with serum PSA in characterizing the presence and site of recurrent cancer. The distinction between local and distant disease recurrence often determines the therapeutic options available to the patient. Patients with only local disease may benefit from adjuvant radiotherapy or cryotherapy. Patients with documented distant disease recurrence, regardless of the presence of local disease, however, most likely require systemic therapy with androgen deprivation. The precise location of distant disease may not be clinically useful in this setting because most patients receive similar therapy. Precise localization of distant recurrences may become important, however, for determining the timing of systemic therapy, the possible use of intermittent androgen deprivation therapy, and the monitoring of clinical response to treatment in such settings as clinical trials. This article examines the imaging modalities currently available to assist in detection and localization of both local and distant recurrent prostate cancer following definitive treatment with either RP, RT, or cryosurgical ablation of the prostate.
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| Address reprint requests to Peter R. Carroll, MD, Department of Urology, U-575, University of California, San Francisco, San Francisco, CA 94143–0738, e-mail: peter_carroll@quickmail.ucsf.edu |
Vol 38 - N° 1
P. 213-229 - janvier 2000 Regresar al número
Artículo precedente
- NEW TREATMENT STRATEGIES IN ADVANCED PROSTATE CANCER
- Eric J. Small, David M. Reese
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