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Radiation is a common form of therapy for patients with newly diagnosed and localized prostate cancer. It has been estimated that nearly one-third of newly diagnosed prostate cancer patients will choose one form of radiation therapy as their primary treatment. Despite modifications of delivering radiation to the gland such as intensity modulation, 3D conformal, and computer-assisted brachytherapy, a significant number of these patients will have a rise in their serum prostate-specific antigen (PSA) value some time after radiation has been administered. Urologists are often called upon to manage patients with rising PSA values and radiation-recurrent cancer.
According to the recent literature, the frequency of biochemical failure with external-beam radiotherapy ranges from 20 to 66%.1–8 However, in the past many investigators used different definitions of biochemical failure. In 1997, the American Society for Therapeutic Radiology and Oncology (ASTRO) defined biochemical failure as three consecutive PSA level rises separated by three- to four-month intervals (ASTRO panel consensus statement). More recently, the Phoenix consensus definition, PSA nadir plus 2ng/ml or more, was introduced.9 Since rising PSA levels can occur with both local and metastatic disease, an elevation does not necessarily imply that the patient has local recurrence. In addition, a PSA level elevation may be due to benign causes. These factors make it difficult to clearly define a locally salvageable population. Only approximately one-third of patients with biochemical failure will have local recurrence.10 If local recurrence is detected early, salvage therapy is feasible. Recent advances in both technology and the technique of salvage cryosurgery have led to the ability to eradicate these tumors with a reduction in morbidity.
Clinically based cryosurgical procedures grounded on well-recognized scientific principles support physician-managed destruction of radiation recurrent tumors of the prostate.11–13 When performed with multiprobe devices and advanced imaging techniques, cryosurgery has yielded predictable and effective results in the long-term treatment of prostate adenocarcinoma in the primary setting.14–16
Prostate geometry dictates cryoneedle/cryoprobe (CN/P) placement: CN/P are placed to support thermal homogeneity at approximately -40°C throughout the prostate. Following template-assisted, ultrasound-guided placement of CN/P, the physician directs freezing from anterior to posterior in the gland. This sequencing supports clear visualization and control of the ablative process under transrectal ultrasound (TRUS).
The main principle of prostate cryosurgery is a thermal therapy that extracts heat (thermal energy) from the targeted tissue, resulting in a series of destructive effects. It has long been recognized that the tissue response from cold injury, which can range from inflammation to total destruction, depends on the severity of freezing. The lesion created by freezing is characterized by coagulation necrosis in the central region with a surrounding, relatively thin, peripheral region in which cell death is apparent. Under ultrasound, the ice ball can be clearly seen as a large hypoechoic region. The outer edge of the ice, which is the warmest part of the ice, can be monitored as it appears as a hyperechoic rim.
Salvage cryosurgery for curative intent should be strongly considered in men who have failed radiation therapy. The most appropriate candidates have documented persistent organ-confined prostate cancer, a PSA <10ng/ml, and a negative metastatic evaluation.