The evolution and state of modern technology for prostate cryosurgery

A Novel, Efficient, Unit Circle-Based, Method for Positioning and Operating Cryo-Surgical Probes in Convex Target Areas

A novel method for positioning and operating needle-like cryo-surgical probes in 2D convex target areas is presented. The method is based on the recorded dynamic performance of a single probe, termed "unit circle," (UC) embedded in a semi-infinite, tissue-like medium. Up to 15 cryo-probes, inserted into the same depth, are operated uniformly for 2-5 min. A predetermined number of probes are rearranged inside the target area until a "tight configuration" is obtained. The probes are initially arranged inside the target area such that the "lethal temperature" circles produced by them are tangent to its contour and to both adjacent lethal temperature circles. Subsequently, all probes are repositioned inwardly, each at a specific distance that depends on the local radius of curvature of the target area. Resulting total "defect areas"-internal and external-for a number of demonstrated cases, amounted to between 2.5% and 7.6% of the target area. The lower values of the defect areas were obtained with increasing numbers of inserted probes coupled with shorter operating times. Possible freezing damages to regions beyond the target area were reduced by up to about 30% for these cases. Similar results were obtained for a case of combined convex-concave target area, treated with additional, externally inserted, heating probes.

The history of cryosurgery in Canada: A tale of two cities

Although not commonly available in Canada, cryosurgery (cryoablation) for prostate cancer has been practiced in many countries. The field of cryoablation has evolved significantly over the past 30 years. Two prostate cryoablation programs were started in Canada in the early 1990s, in London, ON and Calgary, AB, focusing, respectively, on salvage therapy following radiation failure and primary local treatment. This article chronicles the development of the two programs and outlines the scientific and clinical contributions by investigators at the two centers.

Salvage Cryoablation for Radiorecurrent Prostate Cancer: Initial Experience at a Regional Health Care System

CONTEXT

Local recurrence after radiotherapy for prostate cancer remains challenging to treat effectively. Although oncologic control is highest with salvage prostatectomy, the procedure is associated with substantial morbidity.

OBJECTIVE

To identify factors associated with successful salvage cryoablation for radiorecurrent prostate cancer.

DESIGN

We retrospectively reviewed the medical records of patients who underwent salvage cryoablation at our institution between 2005 and 2015. All patients had biopsy-proven local recurrence after radiotherapy. Patients with seminal vesicle invasion or metastases were excluded. Complete follow-up was obtained for all patients.

MAIN OUTCOME MEASURES

Primary study endpoint was biochemical progression-free survival based on the Phoenix criteria.

RESULTS

Seventy-five patients underwent salvage cryotherapy. Mean patient age was 69.3 years. The overall biochemical salvage rate was 50.7% at a median follow-up of 3.9 years. The following factors were independently associated with successful cryotherapy: Precryotherapy Gleason score of 3 + 3 or 3 + 4, low precryotherapy prostate-specific antigen (PSA), low precryotherapy PSA density, longer time to PSA nadir after radiotherapy, and low postcryotherapy PSA nadir. A postcryotherapy PSA nadir of 0.5 ng/mL or less was associated with a biochemical progression-free survival of 79.7% at 3 years and 64.7% at 5 years, whereas a postcryotherapy PSA nadir above 0.5 was associated with a biochemical progression-free survival of 5.6% at 3 years and 0% at 5 years (p < 0.0001).

CONCLUSION

Approximately 50% of the patients achieved biochemical salvage with cryoablation at 5 years. Nadir PSA after salvage was the strongest predictor of biochemical progression-free survival in our cohort.

Impact of preoperative prostate magnetic resonance imaging on the surgical management of high-risk prostate cancer

OBJECTIVE

To evaluate the effect of adding multiparametric magnetic resonance imaging (mpMRI) to pre-surgical planning on surgical decision making for the management of high-risk prostate cancer (HRPC).

PATIENTS AND METHODS

A survey was designed to query multiple centers on surgical decisions of 41 consecutive HRPC cases seen from 2012 to 2015. HRPC was defined by the National Comprehensive Cancer Center Network guidelines. Six fellowship-trained urologic oncologists were asked for their surgical plan in regards to the degree of planned nerve-sparing and lymph node dissection. Two rounds of surveys were administered to six external urologic oncologists. The first survey included the case description only and the second included case description with mpMRI images and report. The correct surgical plan was analyzed by correlation of the degree of planned surgical excision and consistency with the final pathologic evaluation. A priori, an effect size of 20% change was used to determine statistical significance, at p < 0.05.

RESULTS

All cases had at least one change to surgical planning after mpMRI review. Forty (98%) patients had a change in the degree of planned nerve sparing: wider excision in 32% and increased nerve sparing in 24%. After mpMRI the correct surgical plan change was made in 49% for the right and left 51%, decreasing the potential for positive margins. Lymph node dissection was altered from standard to extended lymph node dissection in 17%.

CONCLUSIONS

Although mpMRI is not integrated in guidelines for preoperative planning in HRPC, its use may impact surgical planning, cancer control, and quality of life.

Protection from injury of organs adjacent to a renal tumor during percutaneous cryoablation

Renal cryoablation has become accepted as treatment for small renal tumors as an alternative to surgery. However, parallel with the increase in the use of this therapy, there also has been increases in the number of reports of complications related to renal cryoablation. One potential complication is injury to important non-renal structures adjacent to the ablated renal tumor, such as the colon, duodenum, ureter, psoas muscle and so on. To prevent injury of adjacent organs, separating organs from the tumor is desirable. Over the past 15 years, several techniques have been developed to protect against injury of organs adjacent to renal tumors that are targets of cryoablation. The most commonly used technique for this purpose has been hydrodissection. Others include dissection with gas, balloon dissection and probe traction. To avoid injury of a ureter running near the renal tumor, pyeloperfusion is known to be useful. The rate of cases necessitating avoidance of organ injury by using these techniques is relatively high. In some cases, more than two techniques are combined. In the present review, we provided an overview of techniques currently available to protect against organ injuries, and discussed the advantages and disadvantages of each technique.

A Freezing-Induced Turn-On Imaging Modality for Real-Time Monitoring of Cancer Cells in Cryosurgery

Cryosurgery has attracted much attention for the treatment of tumors owing to its clear advantages. However, determining the volume of frozen tissues in real-time remains a challenge, which greatly lowers the therapeutic efficacy of cryosurgery and hinders its broad application for the treatment of cancers. Herein, we report a freezing-induced turn-on strategy for the selective real-time imaging of frozen cancer cells. As a type of aggregation-induced emission (AIE) fluorogen, TABD-Py molecules interact specifically with ice crystals and form aggregates at the ice/water interface. Consequently, bright fluorescent emission appears upon freezing. TABD-Py molecules are enriched mostly in the cancer cells and exhibit high biocompatibility as well as low cytotoxicity; therefore, a freezing-induced turn-on imaging modality for cryosurgery is developed, which will certainly maximize the therapeutic efficacy of cryosurgery in treating tumors.

Defeating Cancers' Adaptive Defensive Strategies Using Thermal Therapies: Examining Cancer's Therapeutic Resistance, Ablative, and Computational Modeling Strategies as a means for Improving Therapeutic Outcome

BACKGROUND

Diverse thermal ablative therapies are currently in use for the treatment of cancer. Commonly applied with the intent to cure, these ablative therapies are providing promising success rates similar to and often exceeding "gold standard" approaches. Cancer-curing prospects may be enhanced by deeper understanding of thermal effects on cancer cells and the hosting tissue, including the molecular mechanisms of cancer cell mutations, which enable resistance to therapy. Furthermore, thermal ablative therapies may benefit from recent developments in computer hardware and computation tools for planning, monitoring, visualization, and education.

METHODS

Recent discoveries in cancer cell resistance to destruction by apoptosis, autophagy, and necrosis are now providing an understanding of the strategies used by cancer cells to avoid destruction by immunologic surveillance. Further, these discoveries are now providing insight into the success of the diverse types of ablative therapies utilized in the clinical arena today and into how they directly and indirectly overcome many of the cancers' defensive strategies. Additionally, the manner in which minimally invasive thermal therapy is enabled by imaging, which facilitates anatomical features reconstruction, insertion guidance of thermal probes, and strategic placement of thermal sensors, plays a critical role in the delivery of effective ablative treatment.

RESULTS

The thermal techniques discussed include radiofrequency, microwave, high-intensity focused ultrasound, laser, and cryosurgery. Also discussed is the development of thermal adjunctive therapies-the combination of drug and thermal treatments-which provide new and more effective combinatorial physical and molecular-based approaches for treating various cancers. Finally, advanced computational and planning tools are also discussed.

CONCLUSION

This review lays out the various molecular adaptive mechanisms-the hallmarks of cancer-responsible for therapeutic resistance, on one hand, and how various ablative therapies, including both heating- and freezing-based strategies, overcome many of cancer's defenses, on the other hand, thereby enhancing the potential for curative approaches for various cancers.

Salvage image guided radiation therapy to the prostate after cryotherapy failure

Purpose

Cryotherapy is an option for the primary treatment of localized prostate cancer, along with radical prostatectomy, external beam radiation therapy, and brachytherapy. Although it is known that local recurrence can occur in >20% of patients treated with primary cryotherapy, unfortunately there is a paucity of data on later salvage treatments. The use of external beam radiation therapy is an attractive option after cryotherapy failure, but there is little data on its efficacy and toxicity. We evaluated the biochemical control and complication rates of salvage dose-escalated image guided intensity modulated radiation therapy (IG-IMRT) after cryotherapy failure.

Methods and materials

Patients who were treated at our institution from 2005 to 2016 were reviewed for those who underwent cryotherapy as initial treatment followed by salvage IGRT. Patients were treated with dose-escalated IG-IMRT using standard treatment margins of 3 mm posterior and 7 mm in all other directions and daily cone beam computed tomography or kv imaging to implanted fiducial markers. Biochemical progression was defined in accordance with the Phoenix consensus conference definition.

Results

Eight patients were identified as having received post-cryotherapy salvage radiation within the study period. The median total dose was 77.7 Gy (range, 75.6-81.0 Gy). Median follow-up was 55 months (range, 6-88 months). Six patients remained biochemically controlled at the latest follow-up. One patient developed distant metastases after 22 months and one experienced biochemical failure at 30 months with no evidence of distant metastases. No patients experienced acute gastrointestinal toxicities of grade 2 or higher. There were no cases of late gastrointestinal or genitourinary toxicity.

Conclusions

High-dose IG-IMRT results in high rates of salvage and extremely low rates of serious late toxicity for patients with locally recurrent prostate cancer after cryotherapy. Although the results are encouraging, given the small number of patients in this and other series, we remain cautious with regard to this treatment and believe the use of salvage radiation therapy after cryotherapy warrants further study.

Progress toward Optimization of Cryosurgery

Cryosurgery for diverse neoplastic and non-neoplastic diseases has expanded in applicability in recent years, especially since intraoperative ultrasound became available as a method of monitoring the process of tissue freezing. However, persistence of disease after presumably adequate cryosurgical treatment has disclosed deficiencies in the technique, perhaps due to faulty application of the freeze-thaw cycles or due to shortcomings in the imaging method. Clearly cryosurgical technique is less than optimal. The optimal dosimetry for tissue freezing, the recent improvements in imaging techniques, and the need for adjunctive therapy are defined in this review, which assesses the progress toward improving the efficacy of cryosurgery.

The feasibility and safety of repeat cryosurgical ablation of localized prostate cancer

BACKGROUND

The aim of the study was to assess the morbidity and efficacy of repeat cryoablation (CA) in the treatment of localized prostate cancer.

METHODS

Twenty-seven patients with median age of 71 years (range 48-80) who underwent repeat CA between April 2003 and April 2011 at a single institution were included. The median initial prostate-specific antigens (PSA) and Gleason values were 6.2 ng/ml (range 4-23.6) and 7 (range 6-9), respectively. Twenty-four patients underwent two CA treatments, and three patients underwent three CA treatments. Pre- and perioperative parameters and oncological and functional outcomes were evaluated.

RESULTS

No intraoperative complications occurred. After the first CA, PSA was undetectable in 10 patients, and the median nadir PSA value was 0.65 ng/ml (range 0.1-4.9). After the second CA, 4 patients had undetectable PSA, and the median nadir PSA value was 1.25 ng/ml (range 0.2-7.9). For patients who underwent a third CA treatment, no patients had undetectable PSA, and the subsequent median nadir PSA value was 1.6 ng/ml (range 0.4-4.5). Two patients had incontinence (1 pad per day) following repeat CA. One patient had urinary retention after the third CA treatment, and one had urethral stricture. The mean hospitalization and follow-up periods were 1 day (range 0-2) and 51.5 months (range 11-96), respectively.

CONCLUSIONS

Repeat CA successfully reduced PSA levels, and complications were modest. We conclude that repeat CA is a feasible, safe, and effective treatment option for localized prostate cancer.

Focal cryotherapy of localized prostate cancer: a systematic review of the literature

Radical/whole gland treatment for prostate cancer has significant side-effects. Therefore focal treatments such as cryotherapy have been used to treat localized lesions whilst aiming to provide adequate cancer control with minimal side-effects. We performed a systematic review of Pubmed/Medline and Cochrane databases' to yield 9 papers for primary focal prostate cryotherapy and 2 papers for focal salvage treatment (radio-recurrent). The results of 1582 primary patients showed biochemical disease-free survival between 71-93% at 9-70 months follow-up. Incontinence rates were 0-3.6% and ED 0-42%. Recto-urethral fistula occurred in only 2 patients. Salvage focal cryotherapy had biochemical disease-free survival of 50-68% at 3 years. ED occurred in 60-71%. Focal cryotherapy appears to be an effective treatment for primary localized prostate cancer and compares favorably to radical/whole gland treatments in medium-term oncological outcomes and side-effects. Although more studies are needed it is also effective for radio-recurrent cancer with a low complications rates.

Re-purposing cryoablation: a combinatorial 'therapy' for the destruction of tissue

It is now recognized that the tumor microenvironment creates a protective neo-tissue that isolates the tumor from the various defense strategies of the body. Evidence demonstrates that, with successive therapeutic attempts, cancer cells acquire resistance to individual treatment modalities. For example, exposure to cytotoxic drugs results in the survival of approximately 20-30% of the cancer cells as only dividing cells succumb to each toxic exposure. With follow-up treatments, each additional dose results in tumor-associated fibroblasts secreting surface-protective proteins, which enhance cancer cell resistance. Similar outcomes are reported following radiotherapy. These defensive strategies are indicative of evolved capabilities of cancer to assure successful tumor growth through well-established anti-tumor-protective adaptations. As such, successful cancer management requires the activation of multiple cellular 'kill switches' to prevent initiation of diverse protective adaptations. Thermal therapies are unique treatment modalities typically applied as monotherapies (without repetition) thereby denying cancer cells the opportunity to express defensive mutations. Further, the destructive mechanisms of action involved with cryoablation (CA) include both physical and molecular insults resulting in the disruption of multiple defensive strategies that are not cell cycle dependent and adds a damaging structural (physical) element. This review discusses the application and clinical outcomes of CA with an emphasis on the mechanisms of cell death induced by structural, metabolic, vascular and immune processes. The induction of diverse cell death cascades, resulting in the activation of apoptosis and necrosis, allows CA to be characterized as a combinatorial treatment modality. Our understanding of these mechanisms now supports adjunctive therapies that can augment cell death pathways.

Cryotherapy and its applications in the management of urologic malignancies: a review of its use in prostate and renal cancers

Cryotherapy has been established as an ablative modality for the treatment of a wide range of malignancies. Being minimally invasive, it is associated with less morbidity than conventional extirpative surgical procedures. In recent years, it has been used with success for treating two of the common urologic malignancies, that is, prostate and renal cancer. In this review, we highlight the role of cryotherapy as a treatment modality, the proposed destructive mechanisms of action and the risks of its use in the management of prostate and renal malignancy.

Oncological outcome after primary prostate cryoablation compared with radical prostatectomy: a single-centre experience

OBJECTIVE

The aim of this study was to evaluate the oncological outcome after cryoablation of the prostate (CAP) in localized prostate cancer and to compare the results with those of the established treatment of radical prostatectomy (RP) after 7 years of parallel use.

MATERIAL AND METHODS

Forty primary, whole-gland CAP procedures performed on 39 patients from 2006 until 2012 at the Department of Urology, Aarhus University Hospital, were prospectively registered. Patients had a minimum of 12 months' follow-up if they had no recurrent disease. Recurrence was defined by the Phoenix criterion (nadir PSA + 2 ng/ml). Results were compared with oncological outcome in 350 patients who underwent RP over the same period.

RESULTS

Median follow-up after CAP was 29.5 (range 4-75) months. Median age at the time of treatment was 65 (47-78) years. A total of 13 (33%) patients developed recurrent disease after CAP, and in D'Amico low-, intermediate- and high-risk subgroups, recurrence was found in two (33%), five (24%) and six (46%), respectively. Median follow-up after RP was 37 (16-54) months. No cases were excluded. Median age was 64 (34-76) years. Compared with the RP results, where recurrence was found in 62 cases in total (18%), and in three (3%), 30 (21%) and 29(28%) subdivided into risk groups, the risk of recurrent disease was significantly higher after the CAP procedures (p < 0.001).

CONCLUSIONS

Recurrence after CAP was high regardless of risk group, indicating a risk of treating and leaving the tumour in situ. Even small low-risk tumours have the potential for recurrence. At this institution, the oncological outcome after CAP was inferior to that after RP.

High-powered gas-cooled microwave ablation: shaft cooling creates an effective stick function without altering the ablation zone

OBJECTIVE

The purpose of our study was to validate the ability of a new gas-cooled microwave device to secure antennas into tissue before ablation via shaft cooling and to verify that such cooling does not compromise the intended ablation.

MATERIALS AND METHODS

The force required to extract several types of applicators from ex vivo bovine liver before and after ablation was measured. Six groups were compared: cooled needle and multitined radiofrequency electrodes, secured and unsecured cryoprobes, and gas-cooled microwave antennas (n = 6 each). Ablations were next created in in vivo porcine livers for 2 and 10 minutes (n = 6 each) using the gas-cooled microwave system at 140 W. Extraction force was again measured before and after ablation and compared between groups using analysis of variance with post hoc Student t tests. Histologic analysis of the ablation zone was performed to evaluate cellular necrosis along the antenna shaft.

RESULTS

Ex vivo, the secured cryoprobe and microwave antenna required significantly more force to remove than unsecured radiofrequency, cryoprobe, and microwave applicators (p < 0.05, all comparisons). The multitined radiofrequency electrode and cooled radiofrequency electrode required significantly more force to remove after ablation than before ablation (p = 0.006 and 0.02, respectively). In vivo, the secured antenna required significantly more force to remove before ablation than after ablation at both 2 (p < 0.0001) and 10 minutes (p < 0.0001). There was no histologic evidence of cell preservation along the antenna shaft.

CONCLUSION

The gas cooling used in this microwave device can effectively secure antennas into tissue without altering ablation shape or reducing the intended thermal damage.

Percutaneous MR-guided cryoablation of prostate cancer: initial experience

OBJECTIVE

We report our initial experience and the technical feasibility of transperineal prostate cryoablation under MR guidance.

METHODS

Percutaneous MR-guided cryoablation was performed in 11 patients with prostatic adenocarcinoma contraindicated for surgery (mean age: 72 years, mean Gleason score: 6.45, mean prostate-specific antigen (PSA): 6.21 ng/ml, T1-2c/N0/M0, mean: prostate volume 36.44 ml). Free-hand probe positioning was performed under real-time MR imaging. Four to seven cryoprobes were inserted into the prostate, depending on gland volume. The ice ball was monitored using real-time and high-resolution BLADE multi-planar imaging. Patients were followed at 1, 3, 6, 9 and 12 months after the procedure with serum PSA level and post-ablation MRI.

RESULTS

Prostate cryoablation was technically feasible in 10/11 patients. The ice ball was clearly and sharply visualised in all cases as a signal-void area. Mean ice-ball volume was 53.3 ml. Mean follow-up was 15 months (range: 1-25). Mean PSA nadir was 0.33 ng/ml (range: 0.02-0.94 ng/ml). Mean hospitalisation was 5 days (range: 3-13). Complications included a urethro-rectal fistula, urinary infection, transient dysuria and scrotal pain.

CONCLUSIONS

MR-guided prostate cryoablation is feasible and promising, with excellent monitoring of the ice ball. Future perspectives could include the use of MR guidance for focal prostate cancer cryotherapy.

KEY POINTS

• Magnetic resonance allows precise positioning of cryoprobes with real-time imaging. • High-resolution MRI allows excellent monitoring of the developing ice ball. • Cryoablation of prostate cancer under MR guidance is technically feasible. • Further work will refine the procedure and make it even safer.

Treatment profile and complications associated with cryotherapy for localized prostate cancer: a population-based study

The aim of this study was to assess the treatment patterns and 3-12-month complication rates associated with receiving prostate cryotherapy in a population-based study. Men >65 years diagnosed with incident localized prostate cancer in Surveillance Epidemiology End Results (SEER)-Medicare-linked database from 2004 to 2005 were identified. A total of 21,344 men were included in the study, of which 380 were treated initially with cryotherapy. Recipients of cryotherapy versus aggressive forms of prostate therapy (ie, radical prostatectomy or radiation therapy) were more likely to be older, have one co-morbidity, low income, live in the South and be diagnosed with indolent cancer. Complication rates increased from 3 to 12 months following cryotherapy. By the twelfth month, the rates for urinary incontinence, lower urinary tract obstruction, erectile dysfunction and bowel bleeding reached 9.8, 28.7, 20.1 and 3.3%, respectively. Diagnoses of hydronephrosis, urinary fistula or bowel fistula were not evident. The rates of corrective invasive procedures for lower urinary tract obstruction and erectile dysfunction were both <2.9% by the twelfth month. Overall, complications post-cryotherapy were modest; however, diagnoses for lower urinary tract obstruction and erectile dysfunction were common.

CT-guided percutaneous cryoablation of renal masses in selected patients

PURPOSE

We analysed our experience with computed tomography (CT)-guided percutaneous cryoablation (PCA) in patients who were not surgical candidates or refused surgery for small to medium-sized renal masses.

MATERIALS AND METHODS

Two freezing cycles were applied and separated by a passive warming cycle using 1.7- and 2.4-mm cryoprobes under either general anaesthesia or sedation based on patient positioning and respiratory status. Postoperative monitoring included haematological and biochemistry evaluation and CT scan 24 h after PCA. Follow-up consisted of a multislice CT scan at 1 month and every 3 months in the first year then every 6 months thereafter.

RESULTS

Thirty-seven patients (38 lesions) underwent 40 PCA procedures; 5/37 (13.5%) had a solitary kidney. Median mass size was 35 (range 12-70) mm. No complications occurred during the procedure. Clavien grade ≥2 anaemia occurred in two patients (5.4 %): one patient required 1 U of packed red blood cells; the other required an arterial embolisation. Serum creatinine did not increase in any case. Two patients showed persisting or recurrent disease at 1 and 9 months, respectively, and both could be re-treated with PCA. All other patients showed a hypodense mass 3 months after PCA, with no contrast enhancement. Subsequent examinations showed that lesion sizes decreased and CT densitometry remained stable or increased minimally, also with no contrast enhancement.

CONCLUSIONS

PCA proved relatively easy and safe and could be considered an effective alternative for patients who are not surgical candidates or refuse surgery, as well as in patients with medium-sized lesions.

Use of 1,25α dihydroxyvitamin D3 as a cryosensitizing agent in a murine prostate cancer model

Cryotherapy has emerged as a primary treatment option for prostate cancer (CaP); however, incomplete ablation in the periphery of the cryogenic lesion can lead to recurrence. Accordingly, we investigated the use of a non-toxic adjunctive agent, vitamin D3 (VD3), with cryotherapy to sensitize CaP to low temperature-induced, non-ice rupture-related cell death. VD3 (calcitriol) has been identified as a possible adjunct in the treatment of cancer because of its antiproliferative and antitumorigenic properties. This study aimed to identify the cellular responses and molecular pathways activated when VD3 (calcitriol) is combined with cryotherapy in a murine CaP model. Single freeze-thaw events above -15 °C had little effect on cancer cell viability; however, pretreatment with calcitriol in conjunction with cryo significantly increased cell death. The -15 °C calcitriol combination increased cell death to 55% following a single freeze compared with negligible cell loss by freezing or calcitriol alone. Repeated cryo combination yielded 90% cell death compared with 65% in dual freeze-only cycles. Western blot analysis following calcitriol cryosensitization regimes confirmed the activation of apoptosis. Specifically, proapoptotic Bid and procaspase-3 were found to decrease at 1 h following combination treatment, indicating cleavage to the active forms. A parallel in vivo study confirmed the increased cell death when combining cryotherapy with calcitriol pretreatment. The development of an adjunctive therapy combining calcitriol and cryotherapy represents a potentially highly effective, less toxic, minimally invasive treatment option. These results suggest a role for calcitriol and cryo as a combinatorial treatment for CaP, with the potential for clinical translation.

Long-term cancer-specific and overall survival for men followed more than 10 years after primary and salvage cryoablation of the prostate

INTRODUCTION

Ten-year disease-specific survival for clinically localized prostate cancer after radiation is 93%, 88%, and 80% for low-, medium-, and high-risk groups, respectively. The objective of this study was to report long-term cancer survival outcomes for patients who had undergone prostate cryotherapy at our institution more than 10 years ago. To date, this is the longest reported follow-up after cryotherapy.

MATERIALS AND METHODS

A retrospective patient chart review, conducted of an Institutional Review Board (IRB)- approved cryotherapy database, identified 76 men who had undergone prostate cryotherapy before January 1999. Pre-, intra-, and posttreatment data were collected. Primary study endpoints were overall mortality and prostate-cancer-specific death. Secondary endpoints were disease recurrence and clinical progression.

RESULTS

Mean patient age was 69.2 (47.4-86.3) years; median preoperative prostate-specific antigen was 5.3 (0.2-208.0); mean Gleason score was 7. Forty of 76 (52.6%) were confirmed D'Amico high risk. Median follow-up was 10.1 (0.2-14.9) years; 25 patients underwent primary treatment; 51 postradiation. After 10 years of follow-up, 43 of 76 men (56.6%) were still alive; 33 men (43.4%) had died-10 (13.2%) from prostate cancer, 18 (22.4%) from noncancerous causes, and 5 (6.6%) unknown.

CONCLUSIONS

The long-term results of prostate cryotherapy in our series indicate an 87% overall 10-year prostate-cancer-specific survival, despite early cryotherapy technology and the majority of patients being D'Amico high risk.

Pre-conditioning cryosurgery: cellular and molecular mechanisms and dynamics of TNF-α enhanced cryotherapy in an in vivo prostate cancer model system

Cryosurgery is increasingly being used to treat prostate cancer; however, a major limitation is local recurrence of disease within the previously frozen tissue. We have recently demonstrated that tumor necrosis factor alpha (TNF-α), given 4h prior to cryosurgery can yield complete destruction of prostate cancer within a cryosurgical iceball. The present work continues the investigation of the cellular and molecular mechanisms and dynamics of TNF-α enhancement on cryosurgery. In vivo prostate tumor (LNCaP Pro 5) was grown in a dorsal skin fold chamber (DSFC) on a male nude mouse. Intravital imaging, thermography, and post-sacrifice histology and immunohistochemistry were used to assess iceball location and the ensuing biological effects after cryosurgery with and without TNF-α pre-treatment. Destruction was specifically measured by vascular stasis and by the size of histologic zones of injury (i.e., inflammatory infiltrate and necrosis). TNF-α induced vascular pre-conditioning events that peaked at 4h and diminished over several days. Early events (4-24 h) include upregulation of inflammatory markers (nuclear factor-κB (NFκB) and vascular cell adhesion molecule-1 (VCAM)) and caspase activity in the tumor prior to cryosurgery. TNF-α pre-conditioning resulted in recruitment of an augmented inflammatory infiltrate at day 3 post treatment vs. cryosurgery alone. Finally, pre-conditioning yielded enhanced cryosurgical destruction up to the iceball edge at days 1 and 3 vs. cryosurgery alone. Thus, TNF-α pre-conditioning enhances cryosurgical lesions by vascular mechanisms that lead to tumor cell injury via promotion of inflammation and leukocyte (esp. neutrophil) recruitment.

Salvage cryotherapy: is there a role for focal therapy?

Prostate cancer treatment has undergone vast development over the last few decades, but the most notable changes have included nerve-sparing open radical prostatectomy, laparoscopic radical prostatectomy, including robot-assisted and, more recently, cryotherapy and high-intensity focused ultrasound (HIFU). While radical surgery is the current gold standard, the less invasive therapeutic options of cryotherapy and HIFU are regarded as largely experimental by governing bodies. In the case of cryotherapy, a wealth of experience has been accumulated demonstrating its efficacy. Initially used as a salvage treatment for radiation-failed prostate cancer, cryotherapy has been widely used as a primary treatment for localized and locally advanced prostate cancer. More recently, there has been interest expressed in the concept of focal therapy in prostate cancer. This has been evaluated as a primary treatment for prostate cancer, but little information is available regarding the potential use as a salvage treatment. In this article, we evaluate the potential for focal treatment in the salvage setting.

Effects of prostate-rectum separation on rectal dose from external beam radiotherapy

PURPOSE

In radiotherapy for prostate cancer, the rectum is the major dose-limiting structure. Physically separating the rectum from the prostate (e.g., by injecting a spacer) can reduce the rectal radiation dose. Despite pilot clinical studies, no careful analysis has been done of the risks, benefits, and dosimetric effects of this practice.

METHODS AND MATERIALS

Using cadaveric specimens, 20 mL of a hydrogel was injected between the prostate and rectum using a transperineal approach. Imaging was performed before and after spacer placement, and the cadavers were subsequently dissected. Ten intensity-modulated radiotherapy plans were generated (five before and five after separation), allowing for characterization of the rectal dose reduction. To quantify the amount of prostate-rectum separation needed for effective rectal dose reduction, simulations were performed using nine clinically generated intensity-modulated radiotherapy plans.

RESULTS

In the cadaveric studies, an average of 12.5 mm of prostate-rectum separation was generated with the 20-mL hydrogel injections (the seminal vesicles were also separated from the rectum). The average rectal volume receiving 70 Gy decreased from 19.9% to 4.5% (p < .05). In the simulation studies, a prostate-rectum separation of 10 mm was sufficient to reduce the mean rectal volume receiving 70 Gy by 83.1% (p <.05). No additional reduction in the average rectal volume receiving 70 Gy was noted after 15 mm of separation. In addition, spacer placement allowed for increased planning target volume margins without exceeding the rectal dose tolerance.

CONCLUSION

Prostate-rectum spacers can allow for reduced rectal toxicity rates, treatment intensification, and/or reduced dependence on complex planning and treatment delivery techniques.

Adjuvant approaches to enhance cryosurgery

Molecular adjuvants can be used to enhance the natural destructive mechanisms of freezing within tissue. This review discusses their use in the growing field of combinatorial or adjuvant enhanced cryosurgery for a variety of disease conditions. Two important motivations for adjuvant use are: (1) increased control of the local disease in the area of freezing (i.e., reduced local recurrence of disease) and (2) reduced complications due to over-freezing into adjacent tissues (i.e., reduced normal functional tissue destruction near the treatment site). This review starts with a brief overview of cryosurgical technology including probes and cryogens and major mechanisms of cellular, vascular injury and possible immunological effects due to freeze-thaw treatment in vivo. The review then focuses on adjuvants to each of these mechanisms that make the tissue more sensitive to freeze-thaw injury. Four broad classes of adjuvants are discussed including: thermophysical agents (eutectic forming salts and amino acids), chemotherapuetics, vascular agents and immunomodulators. The key issues of selection, timing, dose and delivery of these adjuvants are then elaborated. Finally, work with a particularly promising vascular adjuvant, TNF-alpha, that shows the ability to destroy all cancer within a cryosurgical iceball is highlighted.

The current use and future trends of focal surgical therapy in the management of localized prostate cancer

The current treatment algorithms for management of localized prostate cancer are mainly extirpative in nature. Treatment varies from expectant management to radical prostatectomy or radiation therapy. However, the ever-increasing emphasis on achieving the best survival benefit while better preserving quality of life, coupled with the introduction of new, safer, and efficacious minimally invasive ablative technologies, has led to the increased popularity of minimally invasive treatment (MIT). MIT refers to the use of a wide range of techniques for local target ablation of the prostate gland with minimal damage to the surrounding tissue. Currently these include cryotherapy and high-intensity focused ultrasound. However, other experimental technologies such as photodynamic therapy, interstitial prostate brachytherapy, and microwave and radiofrequency interstitial tumor ablation are also currently under investigation in early clinical trials. To date, the overall interim results for these relatively new modalities of treatment appear comparable to those for surgical and radiation therapies. However, randomized, controlled studies are needed to support use of these modalities as an alternative to surgery and radiation. In this review, we will address the current rationale for and knowledge of MIT with regard to its safety and efficacy in the treatment of localized prostate cancer. In addition, we will discuss future promising tools in MIT such as photodynamic therapy and the target focal therapy approach as a new trend for the treatment of organ-confined low-volume disease.

New Modality for Maximizing Cryosurgical Killing Scope While Minimizing Mechanical Incision Trauma Using Combined Freezing-Heating System

Cryosurgery is a minimally invasive surgical technique using extremely low temperature to destroy undesired tissues. A surgical freezing margin of at least 1 cm is often recommended to avoid local tumor recurrence after surgery. For treating slender or elongated solid tumors in a conventional cryosurgery, simultaneous insertion of multiple cryoprobes is a necessity to guarantee an adequate killing scope. However, the risk of mechanical incision trauma may outweigh the benefits of such therapy. To resolve this difficulty, we proposed a new cryosurgical treatment modality, which can significantly maximize the killing scope while minimize the incision trauma, using the recently developed combined cryosurgical-hyperthermia treatment system (CCHTS). The method, named as one time’s percutaneous insertion while multiple times’ freezing∕heating ablation, is rather flexible in administrating a complex cryosurgical process and avoids certain shortcomings of conventional freezing strategies. Owing to the powerful heating function, the present probe can be easily moved back along its original incision tract to the desired positions immediately after initiating the heating. Then, a new iceball can be formed there while the iceballs generated before still remain unmelted in the following cycles. Consequently, a slender iceball could be generated to embrace the whole elongated tumor. This is, however, rather hard to achieve for a conventional cryosurgery with only one single freezing function or using only one probe. To visually demonstrate the feasibility and potential advantage of the present method, proof of concept in vitro gel experiments were performed. In addition, tests and corresponding theoretical simulations were performed on pork tissues. All the results indicate that the elongated iceball could be easily generated by using only one CCHTS probe owing to its strong freezing∕heating capability. In this way, a large number of incisions with multiple probes, commonly adopted in a conventional cryosurgery, can be avoided and the serious mechanical trauma including potential dangers can thus be significantly reduced. Meanwhile, the cost for the operation and postmedical care will be lowered. The present strategies are expected to be valuable in administrating a highly efficient and minimally invasive cryosurgery in the near future.

[Cryosurgery in the management of prostate cancer]

This article reviews the current status of the prostatic cryosurgery in the management of patients with prostate cancer. Recent advances in cryoablative technology have allowed to treat these patients successfully with decreased morbidity. Using transrectal high-resolution ultrasound imaging, prostate cryotherapy is delivered with multiple ultrathin (17-gauge) cryo-needles, via percutaneous transperineal approach. The extent of freezing can be precisely controlled and monitored with thermic devices, tissue destruction is monitored with real-time visualization of the prostate and surrounding structures, and urethral warming is used to avoid urethral sloughing. However, the results with the second and third-generation cryosurgical equipment will have to be confirmed by means of prospective and randomized trials, because up to now we only have data based on retrospective analyses, which are very heterogeneous. The ability of prostate-specific antigen (PSA) to predict long-term outcome after cryotherapy for localized prostate cancer is not well known because experience with this treatment modality is still limited; however, it seems that a PSA value of 0.5 ng/ml or less after 6 months or longer after cryotherapy would be associated with a high probability (greater than 95%) of negative post-treatment biopsy. Cryosurgery could also be an option of treatment for men with recurrent local disease who have undergone radiotherapy or radical prostatectomy. We have to keep in mind possible complications (incontinence, impotency, urethrorectal fistula or bladder outlet obstruction. The favorable side effect profile and preliminary oncologic and funtional results could suggest that cryosurgery will have a role in the minimally invasive management of selected patients with prostate cancer.

Focal cryosurgery: encouraging health outcomes for unifocal prostate cancer

OBJECTIVES

Owing to the ability to better detect small-volume tumors, we have seen an increasing population of men with low-risk unifocal prostate cancer. We report our safety and efficacy experience of focal cryoablation of the prostate to maintain potency and preserve genitourinary function in men with localized, unifocal disease.

METHODS

From June 2002 to December 2005, 25 patients with primary unifocal prostate cancer were treated with focal cryoablation of the prostate. The patients were followed up with physical examinations, morbidity questionnaires, and prostate-specific antigen (PSA) determinations every 3 months for the first year and every 6 to 12 months thereafter. Patients with a PSA nadir greater than 1.0 ng/mL or a nadir plus 2 ng/mL underwent repeat biopsy to assess for cancer recurrence.

RESULTS

The median age was 68 years (range 48 to 78). The median preoperative PSA level was 6.0 ng/mL, and the postoperative PSA nadir was 2.4 ng/mL. The median follow-up was 28 months. Seventeen patients remained potent. No patients reported worsened lower urinary tract symptoms, incontinence, rectal pain, perineal discomfort, or fistula formation. The median PSA nadir was 2.4 ng/mL, and 40% of patients had a PSA nadir of less than 1.0 ng/mL. Of the 25 patients, 21 (84%) had not experienced biochemical failure, defined as a greater than 50% PSA nadir reduction. Seven patients underwent repeat biopsy, and prostate cancer was detected in the contralateral gland in 2 patients and in the area of previous cryosurgery in 1 patient.

CONCLUSIONS

Focal cryoablation of the prostate has exhibited minimal morbidity and promising efficacy in our 3-year observation. Longer follow-up is necessary to determine its role in the treatment of patients with low-risk unifocal prostate cancer.

Isothermal volume contours generated in a freezing gel by embedded cryo-needles with applications to cryo-surgery

Three-dimensional numerical simulations of multi-cryo-needle surgery were performed with cryo-needle temperature variations taken from matched experimental data. The transient temperatures and frozen volumes generated by simultaneously operating up to three 1.47 mm OD cryo-needles embedded in a phase-changing gel simulating the properties of biological tissues, were studied. In all cases studied, the volumes enclosed by the "lethal", -40 degrees C isotherm, achieved most of their final size in the first few minutes of operation, thus obviating the need for long application times. After 30 min of application of the one-, two- or three-cryo-needles, the ablation ratio attained 3%, 3-6% and 3-8%, respectively, depending on cryo-needle placement configurations. Synergistic effects of using multi-cryo-needles were reflected in the increased expansion of both the radial and axial locations of the isothermal contours. Within each number of cryo-needles used, however, the differences in these locations were rather small, and, as a general rule, tended to somewhat decrease with increasing the placement "density" of the cryo-needles. For each two- and three-cryo-needle application, there is a certain combination of placement configuration and application time that would produce the largest, temperature-specific, volume. As a general guideline, multiple cryo-needles should not be placed too close to each other in order to enhance their synergistic effect. Results of this study should be useful in the design of cryo-needle placement and operation protocols and in understanding the limitations of the freezing-ablation process.

Locally ablative therapies for primary radiation failures: a review and critical assessment of the efficacy

A significant number of men with prostate cancer will experience biochemical failure following treatment with primary radiation therapy. For patients with biopsy-proven recurrent cancer confined to the prostate, local salvage therapy may be a potentially curative treatment option. Most men, however, do not undergo local salvage therapy owing to difficulties in diagnosis as well as concerns over treatment-related complications in the salvage setting. Recently, improvements in technique and technology have substantially reduced the morbidity associated with locally ablative therapies, resulting in an increased interest in the use of minimally invasive therapies such as brachytherapy, cryotherapy, and high-intensity focused ultrasound in the salvage setting. Although these treatments are well tolerated, concerns remain over incomplete and inadequate treatment with locally ablative therapies. Future studies are required to appropriately select candidates for salvage ablative therapies and to determine the long-term oncologic efficacy of these treatments.

Percutaneous cryoablation of large renal masses: technical feasibility and short-term outcome

OBJECTIVE

This retrospective study was performed to assess the feasibility, safety, and short-term outcome of percutaneous cryoablation of large solid renal tumors.

MATERIALS AND METHODS

We reviewed 40 percutaneous cryoablation procedures performed on 40 patients with renal tumors 3 cm in diameter or larger. All patients underwent cryoablation with CT monitoring. Technical success was defined by extension of the ice ball beyond the tumor margin and postablation imaging findings of no contrast enhancement in the area encompassing the original tumor. Complications meeting grade 3 of the National Cancer Institute Common Terminology Criteria for Adverse Events were recorded.

RESULTS

Mean +/- SD tumor diameter was 4.2 +/- 1.1 cm (range, 3.0-7.2 cm). Technical success was achieved in 38 (95%) of 40 cryoablation procedures. There was one grade 3 adverse event (3% rate of significant complications). Follow-up images obtained 3 months or longer (mean, 9 +/- 6 months; range, 3-22 months) after ablation were available for 26 (65%) of the 40 patients. No local tumor recurrence or tumor progression was found.

CONCLUSION

Percutaneous cryoablation of renal tumors measuring 3 cm or larger is technically feasible and relatively safe. Short-term follow-up results are encouraging, although long-term follow-up is necessary to assess true treatment efficacy.