Current State of Urological Cryosurgery: Prostate and Kidney
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REVIEW ARTICLE Current state of urological cryosurgery: prostate and kidney BJUIBJU INTERNATIONAL David Levy, Anthony Avallone and J. Stephen Jones Department of Urology, Cleveland Clinic, Cleveland, OH, USA Accepted for publication 17 December 2009 KEYWORDS prostate, kidney, cryosurgery INTRODUCTION Prostate cancer continues to be the most prevalent cancer in American men and while the lifetime risk of mortality from the disease is ≈4%, we remain unable to identify which individuals actually harbour this risk. PSA measurements alone lack the sensitivity and specificity to identify men at risk for the disease, as well as in predicting organ-confined disease, yet it remains the best tool we have to date. Thus, we remain with the dilemma of who to biopsy, and if the biopsy is positive who to treat. To date, no study has shown oncological superiority for any type of curative therapy for localized prostate cancer and various options exist [1], which leads us to the initial focus of this article. What is the current state of cryosurgery for localized prostate cancer? The second focus regards the use of cryosurgery for management of localized RCC. HISTORICAL PERSPECTIVES multiprobe cryosystems marked an improvement in the delivery of this One of the earliest descriptions of the technology, but procedure-related morbidity application of cryosurgery to the prostate was remained an issue [7]. Limited cryosurgical in 1966 by Soanes et al. [2]. A liquid nitrogen- experience continued, and technical problems based system was used and therapeutic revolved around poor control of the liquid application to the prostate was monitored nitrogen cooling agent, lack of an effective through open incisions or transurethrally urethral warming device [8,9] and inability under direct visualization for both benign and to monitor target tissue temperatures. malignant disease. Limitations in the Subsequently, reports on the role of urethral technology and limited ability to accurately warmers coupled with TRUS guidance place the cryoprobes and monitor the extent represented a significant technological of freezing in real time were characteristics of advancement, which enhanced delivery of the first-generation cryosurgical technique, this therapy with decreased procedure- which ultimately resulted in abandonment related morbidity [10–12]. Target tissue of the technique due to unacceptable temperature monitoring in the form of complication rates [3,4]. Second-generation thermocouple devices became available in the cryotherapy was introduced in the early same period and provided the means to assess 1990s and used TRUS imaging, which allowed the achievement of lethal target tissue for real-time monitoring of the extent of ice temperatures of −40 °C, which became the formation in the tissues [5,6]. This provided endpoint of the freezing cycle. for more accurate cryoprobe placement and more thorough coverage of the prostate. Third-generation cryosurgical technology Transperineal percutaneously introduced became available in 2000, employing delivery © 2010 THE AUTHORS 590 JOURNAL COMPILATION © 2010 BJU INTERNATIONAL | 105, 590–600 | doi:10.1111/j.1464-410X.2010.09235.x UROLOGICAL CRYOSURGERY of pressurized argon gas and helium gas by the AUA in 1996, at which time the Technical components of the procedure through small direct access transperineal treatment was primarily used for patients (freeze rate, achievement of desired target probes, which functioned to deliver cooling with prostate cancer who had failed radiation temperatures and double-freeze technique) and warming properties of the respective therapy [12,13,15]. With continued can enhance cell kill. As stated earlier, the agents based on the Joule–Thompson effect. experience, application of this treatment target tissue temperature to achieve efficient The Joule–Thompson effect is the means by method expanded to individuals with cell kill is −40 °C. Temperatures at the tips of which different gases undergo temperature treatment naïve prostate cancer and today the cryoprobes often exceed −130 °C and changes upon depressurization in accordance cryoablation is used as one component of the while there is no enhanced cell kill beyond with unique gas coefficient properties. minimally invasive approaches to localized −40 °C, those prostate cancer cells in closest Specifically, argon gas undergoes rapid prostate cancer. proximity to the cryoprobes are primarily cooling to – 185.7 °C upon depressurization impacted upon by the freeze-rupture from 20.68 MPa in the storage tank to 0.103 phenomenon, the events that lead to cellular MPa at the tip of the enclosed cryoprobe. The CRYOBIOLOGY rupture due to intracellular ice expansion. expanded gas is then circulated back to the Cells that may not succumb to freeze rupture cryogenic machine through the larger outer Cryosurgical impact on tissues is based on may also undergo necrosis or apoptotic cell lumen of the cryoprobe and attached supply several physiological events. As tissue death [21]. hose to be vented out of the machine into the temperatures decrease to the −15 °C range, surrounding air. Conversely, helium gas extracellular ice forms and results in an warms to 67 °C upon depressurization to osmotic gradient between the newly OUTCOMES provide for active warming of the target dehydrated hyperosmotic extracellular tissues [13] and the historical procedure- compartment and the relatively hypotonic Primary whole gland cryoablation related morbidity and complication rates were intracellular compartments. Intracellular markedly reduced by these developments water flows into the extracellular While biochemical standards of treatment [11,14], as well as by implementation of compartment creating a hyperosmolar toxic success have been established for patients intracelluar undergoing radiation therapy [22] and environment, which surgical extirpation [23], no such criteria exist disrupts vital for the cryosurgical population. In the ‘Cryosurgical ablation of the prostate was intracellular November 2008, publication of the ‘Best removed from the investigative therapies processes. As Practice Statement on Cryosurgery for the list by the AUA in 1996’ temperatures Treatment of Localized Prostate Cancer’ by the decrease to the − AUA [24], there were no data by which the 20 °C range, panel could make a statement about end pinpoint-thermocouple devices that allowed endothelial cell damage occurs [16], resulting points by which cryosurgical treatment for continuous monitoring of target tissue in tissue ischaemia and hypoxia. As success could be measured. temperatures. Additional modifications were temperatures decrease further towards the − new computer software programs that 40 °C range, intracellular ice formation There have been several published reports on provided the surgeon with intraoperative occurs, leading to ‘freeze rupture’ disruption cryosurgical outcomes that have used varying treatment planning and computer-assisted of remaining intracellular structures. PSA threshold levels as one means of assessing cryoprobe placement. Based upon known Components of this degree of thermal insult treatment success. In 2001, Long et al. [25] isotherm data, this allowed the surgeon to have been correlated with apoptosis in the reported 5-year actuarial outcomes from a more strategically place the cryoprobes thus prostate gland [17]. Studies have indicated retrospective multi-institutional cohort of 975 maximizing impact on the targeted tissue, that the lethal temperature for prostate cell risk-stratified patients who underwent while minimizing impact on surrounding death is actually closer to −20 °C [18,19]. prostate cryoablation. In that report the sensitive structures. Variable prostate cell death has been reported biochemical disease-free survival (bDFS) after exposure to temperatures that one outcomes were based upon PSA levels of Cryosurgical ablation of the prostate was would incur at the freeze-zone margin during <0.5 ng/mL and <1.0 ng/mL. In 2002, Bahn removed from the investigative therapies list cryosurgery [20]. et al. [26] reported 7-year actuarial bDFS (1997 © 2010 THE AUTHORS JOURNAL COMPILATION © 2010 BJU INTERNATIONAL 591 LEVY ET AL. American Society of Therapeutic Radiology criteria) patients was 86%, 67% and 51%, and Oncology (ASTRO) criteria [27]) using respectively. For individuals with an initial PSA similar definitions of biochemical failure of level after cryoablation of ≥0.6 ng/mL, the 0.5 ng/mL and 1.0 ng/mL . In 2002, Donnelly 24-month biochemical failure rate was 29.5% et al. [28] reported the 5-year bDFS in a cohort regardless of risk stratification. The referenced of 87 patients using two PSA threshold points, end-point in this study, a PSA level after <0.3 ng/mL and <1.0 ng/mL. Also, in 2002 Ellis cryoablation of < 0.6 ng/mL, was not intended [29] reported outcome data on 93 patients to represent a measure of treatment success. who underwent primary cryoablation of the Rather the value represents a favourable initial prostate, 84% of whom achieved a nadir PSA reading, and an evidence-based component level of ≤0.4 ng/mL, which was used as a of treatment outcomes that will be benchmark of treatment outcome. In 2008, incorporated into a developing definition Jones et al. [30] reported an analysis of a risk- of treatment success that will develop from stratified cohort of 1198 patients from the ongoing and future collaborative studies Cryo On-Line Data (COLD) Registry for whom of primary whole gland cryoablation biochemical success was defined in two populations. manners.