Cryosurgery for Tumors — A Clinical Overview

Cryoablation with KCl Solution Enhances Necrosis and Apoptosis of HepG2 Liver Cancer Cells

Cryoablation has become a valuable treatment modality for the management of liver cancer. However, one of the major challenges in cryosurgery is the incomplete cryodestruction near the edge of the iceball. This issue can be addressed by optimizing cryoablation parameters and administering thermotropic drugs prior to the procedure. These drugs help enhance tumor response, thereby strengthening the destruction of the incomplete frozen zone in liver cance. In the present study, the feasibility and effectiveness of a thermophysical agent, KCl solution, were investigated to enhance the cryodestruction of HepG2 human liver cancer cells. All cryoablation parameters were simultaneously optimized in order to significantly improve the effect of cryoablation, resulting in an increase in the lethal temperature from - 25 °C to - 17 °C. Subsequently, it was found that the application of KCl solution prior to freezing significantly decreased cell viability post-thaw compared to cryoablation treatment alone. This effect was attributed to the eutectic effect of KCl solution. Importantly, it was found that the combination of KCl solution and freezing was less effective when applied to LO2 human liver normal cells. The data revealed that the ratio of mRNA levels of Bcl-2 and bax decreased significantly more in HepG2 cells than in LO2 cells when cryoablation was used with KCl solution. In conclusion, the results of this study demonstrate the effectiveness of KCl solution in promoting cryoablation and describe a novel therapeutic model for the treatment of liver cancer that may distinguish between cancer and normal cells.

CT-Guided Percutaneous Cryoablation of Breast Cancer: A Single-Center Experience

This study shall retrospectively evaluate the efficacy and safety of liquid-nitrogen based CT-guided cryoablation (CA) as a minimal-invasive technique for the curative treatment of primary breast cancer. A total of 45 female patients with 56 tumors were treated by CT-guided CA in analgosedation as an outpatient procedure. We used a liquid-nitrogen based system with a single cryoprobe and performed two freeze cycles with an intermediate thawing. The mean tumor diameter was 1.6 ± 0.7 cm. Follow-up was conducted via contrast-enhanced MR images of the breast. No complications were observed in all 56 ablations. Initial complete ablation was achieved in 100% of cases. Four cases of local tumor progression were reported, resulting in a rate of 8.9%, and 6 cases of intramammary distant recurrence at a rate of 13.3%. The extramammary tumor progression was observed in 7 patients at a rate of 15.6%. The mean overall survival was 4.13 years (95% CI: 3.7-4.5). The mean overall progression-free survival was 2.5 years (95% CI: 1.8-3.2) and the mean local progression-free survival was 2.9 years (95% CI: 2.3-3.6). Cryoablation is a safe and effective treatment for primary breast cancer tumors, which can be performed in analgosedation and as an outpatient procedure. However, potential for improvement exists and further evidence is necessary.

Cryoanalgesia: Review with Respect to Peripheral Nerve

BACKGROUND

 Cryoanalgesia is a tool being used by interventional radiology to treat chronic pain. Within a certain cold temperature range, peripheral nerve function is interrupted and recovers, without neuroma formation. Cryoanalgesia has most often been applied to the intercostal nerve. Cryoanalgesia has applications to peripheral nerve surgery, yet is poorly understood by reconstructive microsurgeons.

METHODS

 Histopathology of nerve injury was reviewed to understand cold applied to peripheral nerve. Literature review was performed utilizing the PubMed and MEDLINE databases to identify comparative studies of the efficacy of intraoperative cryoanalgesia versus thoracic epidural anesthesia following thoracotomy. Data were analyzed using Fisher's exact and analysis of variance tests. A similar approach was used for pudendal cryoanalgesia.

RESULTS

 Application of inclusion and exclusion criteria resulted in 16 comparative clinical studies of intercostal nerve for this review. For thoracotomy, nine studies compared cryoanalgesia with pharmaceutical analgesia, with seven demonstrating significant reduction in postoperative opioid use or postoperative acute pain scores. In these nine studies, there was no association between the number of nerves treated and the reduction in acute postoperative pain. One study compared cryoanalgesia with local anesthetic and demonstrated a significant reduction in acute pain with cryoanalgesia. Three studies compared cryoanalgesia with epidural analgesia and demonstrated no significant difference in postoperative pain or postoperative opioid use. Interventional radiology targets pudendal nerves using computed tomography imaging with positive outcomes for the patient with pain of pudendal nerve origin.

CONCLUSION

 Cryoanalgesia is a term used for the treatment of peripheral nerve problems that would benefit from a proverbial reset of peripheral nerve function. It does not ablate the nerve. Intraoperative cryoanalgesia to intercostal nerves is a safe and effective means of postoperative analgesia following thoracotomy. For pudendal nerve injury, where an intrapelvic surgical approach may be difficult, cryoanalgesia may provide sufficient clinical relief, thereby preserving pudendal nerve function.

Cryosurgery for Basal Cell Skin Cancer of the Head: 15 Years of Experience

The clinical relevance of head and neck (H&N) tumors is related to the potential disfiguration of anatomical structures (by the tumor or surgical intervention), defining patients' individual features and emotional expression, loss or restraint of vital structures functions, and untoward socio-economic sequelae. This study is aimed to improve clinical outcomes of cryosurgery in patients with H&N basal cell skin cancer by refining the indications for cryosurgical treatment. In this study, cryosurgery was used in 234 patients with different stages of cutaneous basal cell carcinoma (BCC) of the head, including 101 patients with T1 tumors, 86-with T2, 5-T3, and 42 patients with tumors relapsing after failure of preceding various treatment modalities. Post-cryosurgery recurrence rate in patients with stage I BCC was 2.7%, with stage II tumors-5.6% and 34.9%-in patients with recurred tumors. Re-recurrence after cryoablation of recurrent tumors correlated with the tumor baseline size. The best aesthetic and long-term clinical results were documented in patients with lesions <1 cm in size with clear boundaries. Thus, cryosurgery is the method of choice for the majority of stage I basal cell carcinomas of the head. For patients with advanced and recurrent skin cancer, cryosurgery is relevant in rare cases selected according to refined indications.

Measurement Analysis of Ice Ball Size during CT-Guided Cryoablation Procedures for Better Prediction of Final Ice Ball Size and Avoidance of Complications

Introduction Cryoablation is the destruction of living tissue by the application of extreme freezing temperature. There has been an increase in the use of cryoablation in the management of musculoskeletal lesions, in particular fibromatosis.

Aim This study aimed to measure the average and relative increase in size of the cryoablation ice ball after the first (10 minutes) and second freeze cycles (20 minutes) to accurately predict the size of the ice ball between first and second freezes to help prevent any unwanted damage of the nearby skin and neurovascular structures. This is especially important when ablating in relatively small body parts such as in the appendicular skeleton.

Material and Methods Eight patients treated with cryoablation over a 12-month period for fibromatosis were, included in the study. The size and volume of the ice ball were measured during the first and second cycle of cryoablation.

Results The average patient age of the cohort was 35.6 years old (min 28 and max 43). There was female predominance in the study (3:2, F:M). There was a significant increase (26%) in the linear dimensions and almost doubling in the volume of the ice ball between freeze cycles (p-value = 0.0037 for dimensions and p-value = 0.0002 for volumes).

Conclusion This pilot study is a preliminary attempt to predict the eventual size of the ice ball during cryoablation procedures when treating cases of fibromatosis. This should help in planning cryoablation to ensure decrease morbidity by preventing injury to adjacent critical structures (neurovascular bundle and skin).

Emerging Liquid Metal Biomaterials: From Design to Application

Liquid metals (LMs) as emerging biomaterials possess unique advantages including their favorable biosafety, high fluidity, and excellent electrical and thermal conductivities, thus providing a unique platform for a wide range of biomedical applications ranging from drug delivery, tumor therapy, and bioimaging to biosensors. The structural design and functionalization of LMs endow them with enhanced functions such as enhanced targeting ability and stimuli responsiveness, enabling them to achieve better and even multifunctional synergistic therapeutic effects. Herein, the advantages of LMs in biomedicine are presented. The design of LM-based biomaterials with different scales ranging from micro-/nanoscale to macroscale and various components is explored in-depth to promote the understanding of structure-property relationships, guiding their performance optimization and applications. Furthermore, the related advanced progress in the development of LM-based biomaterials in biomedicine is summarized. Current challenges and prospects of LMs in the biomedical field are also discussed.

Systematic Review of Focal and Salvage Cryotherapy for Prostate Cancer

Cryotherapy is one of the recognised ablative modalities for both primary and salvage therapy for prostate cancer. It presents an alternative, less invasive treatment for an organ-confined disease, improved preservation of surrounding tissue and a more suitable option for patients who are unfit for radical prostatectomy. Nevertheless, the currently available literature is relatively too scarce to provide definite conclusions regarding the treatment outcomes in cryotherapy. The present study aimed to review current oncological and survival outcomes in cryotherapy for primary and recurrent prostate cancer. Furthermore, this study aimed to establish the complications and functional outcomes of cryotherapy for prostate cancer. A literature search was performed on the PubMed, Cochrane and Google Scholar databases. Current guidelines and recommendations from the European Association of Urology were also reviewed. The search keywords used included ‘Cryotherapy, Prostate Cancer’, ‘Cryoablation, Prostate Cancer’ and ’Cryosurgery, Focal Prostate Cancer’. Truncations and Boolean operators were used with the keywords. All relevant studies from after 2015, including abstracts and non-English research assessing oncological and functional outcomes and complications, were included. Twenty-six studies consisting of 11,228 patients were reviewed. Fifteen studies assessed the outcomes of primary cryotherapy, whereas 11 studies reported the outcomes in salvage therapy. The patient's age ranged 55-85 years, and the pre-procedural prostate-specific antigen (PSA) ranged 0.01-49.33 ng/mL. A total of 2031 patients were classified to be at low risk, 2,995 were at moderate risk and 253 were at high risk on the D’Amico prostate cancer risk classification system. Follow-ups ranged from 9.0 to 297.6 months. The disease-specific survival rate was 65.5%-100.0%, overall survival was 61.3%-99.1%, the PSA nadir was 0.01-2.63 ng/mL and the overall biochemical recurrence rate was 15.4%-62.0%. The complications included erectile dysfunction (3.7%-88.0%), urinary retention (2.13%-25.30%) and bladder neck stricture/stenosis (3.0%-16.7%). The functional assessment showed a mixture of improved, unchanged or worsened post-procedural outcomes in primary therapy. This systematic review did not find significant differences in the cancer-specific, overall and biochemical-free survival rate between the primary and salvage cryotherapy cohorts. The most common complications encountered in both cohorts were erectile dysfunction, urinary incontinence, lower urinary tract/bladder neck stricture and infection. More prospective and double-arm studies are critically needed to provide guidance on the careful selection of patient cohorts for cryotherapy, whether for curative or salvage intent.

Cryoablation Without Excision for Low-Risk Early-Stage Breast Cancer: 3-Year Interim Analysis of Ipsilateral Breast Tumor Recurrence in the ICE3 Trial

BACKGROUND

The ICE3 trial is designed to evaluate the safety and efficacy of breast cryoablation, enabling women older than 60 years with low-risk early-stage breast cancers to benefit from a nonsurgical treatment and to avoid the associated surgical risks.

METHODS

The ICE3 trial is a prospective, multi-center, single-arm, non-randomized trial including women age 60 years or older with unifocal, ultrasound-visible invasive ductal carcinoma size 1.5 cm or smaller and classified as low to intermediate grade, hormone receptor (HR)-positive, and human epidermal growth factor receptor 2 (HER2)-negative. Ipsilateral breast tumor recurrence (IBTR) at 5 years was the primary outcome. A 3-year interim analysis of IBTR was performed, and the IBTR probability was estimated using the Kaplan-Meier method.

RESULTS

Full eligibility for the study was met by 194 patients, who received successful cryoablation per protocol. The mean age was 75 years (range, 55-94 years). The mean tumor length was 8.1 mm (range, 8-14.9 mm), and the mean tumor width was 7.4 mm (range, 2.8-14 mm). During a mean follow-up period of 34.83 months, the IBTR rate was 2.06% (4/194 patients). Device-related adverse events were reported as mild in 18.4% and moderate in 2.4% of the patients. No severe device-related adverse events were reported. More than 95% of the patients and 98% of the physicians reported satisfaction with the cosmetic results at the clinical follow-up evaluation.

CONCLUSIONS

Breast cryoablation presents a promising alternative to surgery while offering the benefits of a minimally invasive procedure with minimal risks. Further study within a clinical trial or registry is needed to confirm cryoablation as a viable alternative to surgical excision for appropriately selected low-risk patients.

Breast Cancer Cryoablation: Assessment of the Impact of Fundamental Procedural Variables in an In Vitro Human Breast Cancer Model

INTRODUCTION

Breast cancer is the most prominent form of cancer and the second leading cause of death in women behind lung cancer. The primary modes of treatment today include surgical excision (lumpectomy, mastectomy), radiation, chemoablation, anti-HER2/neu therapy, and/or hormone therapy. The severe side effects associated with these therapies suggest a minimally invasive therapy with fewer quality of life issues would be advantageous for treatment of this pervasive disease. Cryoablation has been used in the treatment of other cancers, including prostate, skin, and cervical, for decades and has been shown to be a successful minimally invasive therapeutic option. To this end, the use of cryotherapy for the treatment of breast cancer has increased over the last several years. Although successful, one of the challenges in cryoablation is management of cancer destruction in the periphery of the ice ball as the tissue within this outer margin may not experience ablative temperatures. In breast cancer, this is of concern due to the lobular nature of the tumors. As such, in this study, we investigated the level of cell death at various temperatures associated with the margin of a cryogenic lesion as well as the impact of repetitive freezing and thawing methods on overall efficacy.

METHODS

Human breast cancer cells, MCF-7, were exposed to temperatures of -5°C, -10°C, -15°C, -20°C, or -25°C for 5-minute freeze intervals in a single or repeat freeze-thaw cycle. Samples were thawed with either passive or active warming for 5 or 10 minutes. Samples were assessed at 1, 2, and 3 days post-freeze to assess cell survival and recovery. In addition, the modes of cell death associated with freezing were assessed over the initial 24-hour post-thaw recovery period.

RESULTS

Exposure of MCF-7 cells to -5°C and -10°C resulted in minimal cell death regardless of the freeze/thaw conditions. Freezing to a temperature of -25°C resulted in complete cell death 1 day post-thaw with no cell recovery in all freeze/thaw scenarios evaluated. Exposure to a single freeze event resulted in a gradual increase in cell death at -15°C and -20°C. Application of a repeat freeze-thaw cycle (dual 5-minute freeze) resulted in an increase in cell death with complete destruction at -20°C and near complete death at -15°C (day 1 survival: single -15°C freeze/thaw = 20%; repeated -15°C freeze/thaw = 4%). Analysis of thaw interval time (5 vs 10 minute) demonstrated that the shorter 5-minute thaw interval between freezes resulted in increased cell destruction. Furthermore, investigation of thaw rate (active vs passive thawing) demonstrated that active thawing resulted in increased cell survival thereby less effective ablation compared with passive thawing (eg, -15°C 5/10/5 procedure survival, passive thaw: 4% vs active thaw: 29%).

CONCLUSIONS

In summary, these in vitro findings suggest that freezing to temperatures of 25°C results in a high degree of breast cancer cell destruction. Furthermore, the data demonstrate that the application of a repeat freeze procedure with a passive 5-minute or 10-minute thaw interval between freeze cycles increases the minimal lethal temperature to the -15°C to -20°C range. The data also demonstrate that the use of an active thawing procedure between freezes reduces ablation efficacy at temperatures associated with the iceball periphery. These findings may be important to improving future clinical applications of cryoablation for the treatment of breast cancer.

Evaluation of a Novel Cystoscopic Compatible Cryocatheter for the Treatment of Bladder Cancer

BACKGROUND: As the acceptance of cryoablative therapies for the treatment of non-metastatic cancers continues to grow, avenues for novel cryosurgical technologies and approaches have opened. Within the field of genitourinary tumors, cryosurgical treatments of bladder cancers remain largely investigational. Current modalities employ percutaneous needles or transurethral cryoballoons or sprays, and while results have been promising, each technology is limited to specific types and stages of cancers. OBJECTIVE: This study evaluated a new, self-contained transurethral cryocatheter, FrostBite-BC, for its potential to treat bladder cancer. METHODS: Thermal characteristics and ablative capacity were assessed using calorimetry, isothermal analyses, in vitro 3-dimensional tissue engineered models (TEMs), and a pilot in vivo porcine study. RESULTS: Isotherm assessment revealed surface temperatures below – 20°C within 9 sec. In vitro TEMs studies demonstrated attainment of ≤– 20°C at 6.1 mm and 8.2 mm in diameter following single and double 2 min freezes, respectively. Fluorescent imaging 24 hr post-thaw revealed uniform, ablative volumes of 326.2 mm3 and 397.9 mm3 following a single or double 2 min freeze. In vivo results demonstrated the consistent generation of ablative areas. Lesion depth was found to correlate with freeze time wherein 15 sec freezes resulted in ablation confined to the sub-mucosa and ≥30 sec full thickness ablation of the bladder wall. CONCLUSIONS: These studies demonstrate the potential of the FrostBite-BC cryocatheter as a treatment option for bladder cancer. Although preliminary, the outcomes of these studies were encouraging, and support the continued investigation into the potential of the FrostBite-BC cryocatheter as a next generation, minimally invasive cryoablative technology.

Rapid Freezing Enables Aminoglycosides To Eradicate Bacterial Persisters via Enhancing Mechanosensitive Channel MscL-Mediated Antibiotic Uptake

Bacterial persisters exhibit noninherited antibiotic tolerance and are linked to the recalcitrance of bacterial infections. It is very urgent but also challenging to develop antipersister strategies. Here, we report that 10-s freezing with liquid nitrogen dramatically enhances the bactericidal action of aminoglycoside antibiotics by 2 to 6 orders of magnitude against many Gram-negative pathogens, with weaker potentiation effects on Gram-positive bacteria. In particular, antibiotic-tolerant Escherichia coli and Pseudomonas aeruginosa persisters-which were prepared by treating exponential-phase cells with ampicillin, ofloxacin, the protonophore cyanide m-chlorophenyl hydrazone (CCCP), or bacteriostatic antibiotics-can be effectively killed. We demonstrated, as a proof of concept, that freezing potentiated the aminoglycosides' killing of P. aeruginosa persisters in a mouse acute skin wound model. Mechanistically, freezing dramatically increased the bacterial uptake of aminoglycosides regardless of the presence of CCCP, indicating that the effects are independent of the proton motive force (PMF). In line with these results, we found that the effects were linked to freezing-induced cell membrane damage and were attributable, at least partly, to the mechanosensitive ion channel MscL, which was able to directly mediate such freezing-enhanced aminoglycoside uptake. In view of these results, we propose that the freezing-induced aminoglycoside potentiation is achieved by freezing-induced cell membrane destabilization, which, in turn, activates the MscL channel, which is able to effectively take up aminoglycosides in a PMF-independent manner. Our work may pave the way for the development of antipersister strategies that utilize the same mechanism as freezing but do so without causing any injury to animal cells.IMPORTANCE Antibiotics have long been used to successfully kill bacterial pathogens, but antibiotic resistance/tolerance usually has led to the failure of antibiotic therapy, and it has become a severe threat to human health. How to improve the efficacy of existing antibiotics is of importance for combating antibiotic-resistant/tolerant pathogens. Here, we report that 10-s rapid freezing with liquid nitrogen dramatically enhanced the bactericidal action of aminoglycoside antibiotics by 2 to 6 orders of magnitude against many bacterial pathogens in vitro and also in a mouse skin wound model. In particular, such combined treatment was able to effectively kill persister cells of Escherichia coli and Pseudomonas aeruginosa, which are per se tolerant of conventional treatment with bactericidal antibiotics for several hours. We also demonstrated that freezing-induced aminoglycoside potentiation was apparently linked to freezing-induced cell membrane damage that may have activated the mechanosensitive ion channel MscL, which, in turn, was able to effectively uptake aminoglycoside antibiotics in a proton motive force-independent manner. Our report sheds light on the development of a new strategy against bacterial pathogens by combining existing antibiotics with a conventional physical treatment or with MscL agonists.

Combined carbon dioxide laser and cryosurgical ablation of rostral nasal septum squamous cell carcinoma in 10 dogs

BACKGROUND

Squamous cell carcinoma (SCC) is the most commonly reported neoplasm of the nasal planum and treatment is focused on localized disease. Rostral maxillectomy and/or nasal planectomy are considered standard of care for excision of nasal planum SCC; however, the cosmetic outcome of these procedures can be deemed unacceptable by many pet owners.

OBJECTIVES

The study aim was to evaluate the efficacy of combination carbon dioxide (CO₂ ) laser surgery and cryosurgery as a palliative treatment modality in dogs with nasal SCCs.

ANIMALS

Ten client-owned dogs with nasal SCC were included: seven neutered males, two spayed females and one intact male, with a median age of 12.5 years (range 9-15 years).

METHODS AND MATERIALS

Tumour CO₂ laser ablation was followed by cryosurgical ablation of the visible tumour, adjacent and subjacent tissue. Three rapid freeze-slow thaw cycles were performed.

RESULTS

Eight of 10 dogs were Labrador retrievers. The ages ranged from 9 to 14 years. Overall median survival time was 260 days with two dogs still alive at the time of writing.

CONCLUSIONS AND CLINICAL IMPORTANCE

Combined CO₂ laser and cryosurgical ablation was practical, cost-effective and provided an excellent aesthetic outcome in dogs with SCCs restricted to the nasal septum, while providing acceptable palliation of local disease.

Assessment of a novel cryoablation device for the endovascular treatment of cardiac tachyarrhythmias

Objectives

Cryoablation is an effective alternative treatment for cardiac arrhythmias offering shortened recovery and reduced side effects. As the use of cryoablation increases, the need for new devices and procedures has emerged. This has been driven by technological limitations including lengthy periods to generate a single lesion (3-5 min), uncertain transmurality, and differential efficacy. Furthermore, due to limited ablation capacity under high heat loads, cryo has had limited success in the treatment of ventricular arrhythmias. To this end, in this study we evaluated a new cryoablation catheter, ICEolate, for the targeted ablation of cardiac tissue.

Methods

Performance assessment included calorimetry, freeze zone isothermal distribution characterization and catheter ablation capacity in a submerged, circulating, heat-loaded ex vivo tissue model. A pilot in vivo study was also conducted to assess ablative capacity of the cryocatheter in a fully beating heart.

Results

Ex vivo studies demonstrated ice formation at the tip of a cryocatheter within 5 s and a tip temperature of ~-150°C within 10 s. The device repeatedly generated freeze zones of 2 cm × 3 cm in less than 2 min. Tissue model studies revealed the generation of a full thickness (5-10 mm) cryogenic lesion within 1 min with an opposite (transmural) surface temperature of <-60°C under a circulating 37°C heat load. Pilot in vivo studies demonstrated the delivery of an ablative "dose," producing a continuous full thickness transmural linear lesion in <60 s at both atrial and ventricular sites.

Conclusion

These studies suggest that the supercritical nitrogen cryodevice and ICEolate cryocatheter may provide for rapid, effective, controllable freezing of targeted tissue. The ablative power, speed, and directional freeze characteristics also offer the potential of improved safety via a reduction in procedural time compared to current cryoablation devices. These technological developments may open new avenues for the application of cryo to treat other cardiac arrhythmogenic disorders.

Computational study of the effects of arterial bifurcation on the temperature distribution during cryosurgery

BACKGROUND

Thermally significant blood flows into locally cooled diseased tissues and warm them during cryosurgery so that the iceball is often hard to cover the whole diseased volume. This paper is aimed at investigating the effects of large arterial bifurcation on the temperature distribution during cryosurgery through simulation method.

METHODS

A parametric geometry model is introduced to construct a close-to-real arterial bifurcation. The three-dimensional transient conjugate heat transfer between bifurcated artery and solid tissues with phase change during cryosurgery is performed by finite volume method.

RESULTS

The discussion was then made on the effects of the relative position between cryoprobe and artery bifurcation, the inlet velocity of root artery and the layout of multiple cryoprobes on the temperature distribution and iceball evolution. The results show that the thermal interaction between blood flow and iceball growth near bifurcation is considerable complex. The thermal effects of bifurcation could modulate the iceball morphology, severely weaken its freezing volume and prevent the blood vessel from being frozen.

CONCLUSION

The present work is expected to be valuable in optimizing cryosurgery scheme of the situation that the bifurcated artery is embedded into the disease tissue.

Assessment of Cryosurgical Device Performance Using a 3D Tissue-Engineered Cancer Model

As the clinical use of cryoablation for the treatment of cancer has increased, so too has the need for knowledge on the dynamic environment within the frozen mass created by a cryoprobe. While a number of factors exist, an understanding of the iceball size, critical isotherm distribution/penetration, and the resultant lethal zone created by a cryoprobe are critical for clinical application. To this end, cryoprobe performance is typically characterized based on the iceball size and temperature penetration in phantom gel models. Although informative, these models do not provide information as to the impact of heat input from surrounding tissue nor give any information on the ablative zone created. As such, we evaluated the use of a tissue-engineered tumor model (TEM) to assess cryoprobe performance including iceball size, real-time thermal profile distribution, and resultant ablative zone. Studies were conducted using an Endocare V-probe cryoprobe, with a 10/5/10 double freeze–thaw protocol using prostate and renal cancer TEMs. The data demonstrate the generation of a 33- to 38-cm3 frozen mass with the V-Probe cryoprobe following the double freeze of which ∼12.7 and 6.5 cm3 was at or below −20°C and −40°C, respectively. Analysis of ablation zone using fluorescence microscopy 24 hours postthaw demonstrated that the internal ∼40% of the frozen mass was completely ablated, whereas in the periphery of the iceball (outer 1 cm region), a gradient of partial to minimal destruction was observed. These findings correlated well with clinical reports on renal and prostate cancer cryoablation. Overall, this study demonstrates that TEMs provide an effective model for a more complete characterization of cryoablation device performance. The data demonstrate that while the overall iceball size generated in the TEM was consistent with published reports from phantom models, the integration of an external heat load, circulation, and cellular components more closely reflect an in vivo setting and the impact of penetration of the critical (−20°C and −40°C) isotherms into the tissue. This is important as it is well appreciated in clinical practice that the heat load of a tissue, cryoprobe proximity to vasculature, and so on, can impact outcome. The TEM model provides a means of characterizing the impact on ablative dose delivery allowing for a better understanding of probe performance and potential impact on ablative outcome.

Effect of Transcatheter Arterial Chemoembolization Combined with Argon-Helium Cryosurgery System on the Changes of NK Cells and T Cell Subsets in Peripheral Blood of Hepatocellular Carcinoma Patients

Hepatocellular carcinoma (HCC) is one of the most aggressive tumors in humans. T lymphocytes and natural killer (NK) cells are the body's first line of defense to prevent tumor cell growth. Previous studies have demonstrated that transcatheter arterial chemoembolization (TACE) combined with argon-helium cryosurgery system (AHCS) can effectively treat liver cancer. However, the mechanism of the treatment is unclear yet. In the current study, we investigated the effects of TACE combined with AHCS on the changes of T cell subsets and NK cells in peripheral blood of HCC. Our data show that alpha-fetoprotein (AFP) levels in peripheral blood were significantly up-regulated in HCC patients before treatment when compared with healthy people and reduced after TACE combined with AHCS treatment (P < 0.01). In addition, we found that CD4+ cells and NK cells decreased (P < 0.05) and CD8+ cells increased (P < 0.05) in HCC patients when compared with healthy people. After treatment, the CD4+ cells, CD4+/CD8+ ratio, and NK cells were dramatically increased in HCC patients (P < 0.05). In contrast, CD8+ cells were significantly decreased (P < 0.05). TACE combined with AHCS treatment significantly prolonged 1-year survival rate of HCC patients and did not show significant side effects. Taken together, our data indicate that TACE combined with AHCS treatment improves patients' immune system. It is a feasible and effective therapeutic method for HCC patients.

Characterization of Pancreatic Cancer Cell Thermal Response to Heat Ablation or Cryoablation

One of the most lethal carcinomas is pancreatic cancer. As standard treatment using chemotherapy and radiation has shown limited success, thermal regimens (cryotherapy or heat ablation) are emerging as viable alternatives. Although promising, our understanding of pancreatic cancer response to thermal ablation remains limited. In this study, we investigated the thermal responses of 2 pancreatic cancer cell lines in an effort to identify the minimum lethal temperature needed for complete cell death to provide guidance for in vivo applications. PANC-1 and BxPC-3 were frozen (-10°C to -25°C) or heated (45°C-50°C) in single and repeated exposure regimes. Posttreatment survival and recovery were analyzed using alamarBlue assay over a 7-day interval. Modes of cell death were assessed using fluorescence microscopy (calcein acetoxymethyl ester/propidium iodide) and flow cytometry (YO-PRO-1/propidium iodide). Freezing to -10°C resulted in minimal cell death. Exposure to -15°C had a mild impact on PANC-1 survival (93%), whereas BxPC-3 was more severely damaged (33%). Exposure to -20°C caused a significant reduction in viability (PANC-1 = 23%; BxPC-3 = 2%) whereas -25°C yielded complete death. Double freezing exposure was more effective than single exposure. Repeat exposure to -15°C resulted in complete death of BxPC-3, whereas -20°C severely impacted PANC-1 (7%). Heating to 45°C resulted in minimum cell death. Exposure to 48°C yielded a slight increase in cell loss (PANC-1 = 85%; BxPC-3 = 98%). Exposure to 50°C caused a significant decline (PANC-1 = 70%; BxPC-3 = 9%) with continued deterioration to 0%. Double heating to 45°C resulted in similar effects observed in single exposures, whereas repeated 48°C resulted in significant increases in cell death (PANC-1 = 68%; BxPC-3 = 29%). In conclusion, we observed that pancreatic cancer cells were completely destroyed at temperatures <-25°C or >50°C using single thermal exposures. Repeated exposures resulted in increased cell death at less extreme temperatures. Our data suggest that thermal ablation strategies (heat or cryoablation) may represent a viable technique for the treatment of pancreatic cancer.

Cryoinjury of MCF-7 Human Breast Cancer Cells and Inhibition of Post-Thaw Recovery Using TNF-α

Cryoinjury of MCF-7 human breast cancer cells and its enhancement using tumor necrosis factor-alpha (TNF-α) as an adjuvant, were investigated. Through a series of experiments in a two level factorial design critical parameters affecting cryotherapy responses were identified. The cryoinjury was investigated by quantifying the effects of four freeze/thaw (F/T) parameters, selected to be within the expected range for a cryosurgical iceball. Thermal parameters considered were cooling rate (5 and 50 °C/min), end temperature (−20 and −80 °C), hold time (0 and 10 min), and thawing rate (20 and 100 °C/min). After exposing the cells to the selected F/T conditions, survival was assessed and statistically analyzed to determine the effect of each parameter and their interactions. A statistical analysis shows that the end temperature and hold time were the two most significant parameters in the range studied. This suggests that proper control of these two parameters is important to achieve desired cryodestruction of MCF-7 cells. Enhancement of cryoinjury by TNF-α was also investigated in a tissue equivalent cryoinjury model in which a cryosurgical iceball is formed. MCF-7 cells cultured in a collagen matrix underwent a controlled F/T with or without TNF-α pre-treatment at 100 ng/ml for 24 hours. Post-thaw viability of MCF-7 cells was assessed at three hours, and at one and three days after freezing. Although the TNF-α treatment alone induced neither apoptotic nor necrotic cell death, the combination of TNF-α pre-treatment and freezing enhanced the immediate cryoinjury of MCF-7 cells, and significantly impaired the post-thaw recovery. Without TNF-α treatment, MCF-7 cell cultures were repopulated, reaching approximately 80% survival at day 3 even after severe cryoinjury (≤ 20% survival) at three hours. In contrast, this repopulation was significantly inhibited by TNF-α pre-treatment, in which case the viability of the frozen region remained below 40% at day 3. The effects of TNF-α on the cryoinjury of MCF-7 cells suggest that TNF-α may serve as a potent adjuvant to cryosurgery of breast cancer.

Percutaneous Tumor Ablation: Cryoablation Facilitates Targeting of Free Epirubicin-Ethanol-Ioversol Solution Interstitially Coinjected in a Rabbit VX2 Tumor Model

This acute study was aimed at exploring the ability of a cryoablative lesion to drive the distribution of a concomitant in situ injection of a free epirubicin-ethanol-ethiodol-methylene blue mixture. We report the feasibility and safety of this new percutaneous computed tomography-guided combinatorial ablative procedure on VX2 tumors. Eight New Zealand white rabbits bearing 16 tumors on both side of the back muscle were randomly selected and treated on the same day with the following procedures: (1) 8 concomitant cryoablation and interstitial chemotherapy and (2) 8 intratumor marginal chemotherapy. For the latter, an injection needle was positioned at the inner distal margin of a first selected tumor side, where the chemotherapy was delivered during 5 serial sequences. For the concomitant therapy, a single cryoneedle maintained the ice front at the tumor margin, where a needle delivered the drug dose during 5 freeze-injection-thaw sequences. Enhanced computed tomography scans on days 3, 7, and 10 assessed the tumor contours and the tracer localization. Two rabbits were killed on days 0, 3, 7, and 10 for gross and histopathological analyses. During the concomitant therapy, ioversol was distributed at the tumor and iceball margins along with the methylene blue. Enhanced computed tomography on days 3, 7, and 10 showed a focal enlarging defect of the tumor marginal enhancing rim. The rim coincided with focal necrosis at histopathology. During the intratumor chemotherapy procedure, computed tomography showed that the tracers distributed mostly over the tumor mass. No marginal necrosis was detected at histopathology. On day 10, the tumor size for the intratumor chemotherapy group was twice that of the concomitant therapy group. No adverse events were observed. In this VX2 tumor model, our image-guided concomitant therapy is feasible and may enhance the effectiveness of a free epirubicin tracer mixture at the tumor margin.

Ultrasound-guided cryoablation of breast fibroadenoma: a pilot trial

PURPOSE

The aim of the study was to evaluate cryoablation (CA) under ultrasound guidance in the office setting with liquid nitrogen system for patients with fibroadenoma (FA).

METHODS

For this prospective multicenter trial, an office-based cryosurgical system was used to treat histological confirmed benign FA with a maximum dimension of 3 cm. Sixty CA procedures were performed under ultrasound guidance. A freeze-thaw-freeze treatment cycle was performed according to the size of the FA. During the CA procedure continuous ultrasound monitoring was performed, verifying engulfment of the FA. Patients attended four follow-up visits at 1 week, 3, 6 months and 1 year and underwent ultrasound, physical examination and photography.

RESULTS

Data were collected and analyzed in 60 cases. 59 of 60 FA (98 %) were fully engulfed by the ice ball. No serious adverse events occurred related to the IceSense3 system. At the 1-year follow-up, the FAs were gone in 93% of the cases. Prior to CA procedure, 76% of the FAs were palpable. Afterwards in some cases (22%), a scar/cryo lesion was palpable. 28% of the patients reported pain, described as mild or moderate, compared to 2% after 1 year. Cosmetic results at 12 months follow-up were reported as good or excellent in 100% by physician and in 97% by patients.

CONCLUSIONS

The cryodestruction of the FA using liquid nitrogen system proved functional and safe, while showing meaningful reduction in volume, palpability, pain and cosmetic satisfying outcomes.

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.

Evaluation of a novel cryoablation system: in vitro testing of heat capacity and freezing temperatures

OBJECTIVE

Cryoablation has been used to ablate cardiac tissue for decades and has been shown to be able to replace incisions in the surgical treatment of atrial fibrillation. This in vitro study evaluates the performance of a novel cryoprobe and compares it with existing commercially available devices.

METHODS

A new malleable 10-cm aluminum cryoprobe was compared with a rigid 3.5-cm copper linear probe using in vitro testing to evaluate performances under different thermal loads and with different tissue thicknesses. Radial dimensions of ice formation were measured in each water bath by a high-precision laser 2 minutes after the onset of cooling. Probe-surface temperatures were recorded by thermocouples. Tissue temperature was measured at depths of 4 mm and 5 mm from the probe-tissue interface. Time to reach a tissue temperature of -20°C was recorded.

RESULTS

Ice formation increased significantly with lower water-bath temperatures (P < 0.001). Width and depth of ice formation were significantly less for the rigid linear probe (P < 0.012 and P < 0.001, respectively). There was no difference between the probes in the maximal negative temperature reached under different thermal loads or at different tissue depths. The malleable probe achieved significantly lower temperatures at the proximal compared with the distal end (-61.7°C vs -55.0°C, respectively; P < 0.001). A tissue temperature of -20°C was reached earlier at 4 mm than at 5 mm (P < 0.001) and was achieved significantly faster with the 3011 Maze Linear probe (P < 0.021).

CONCLUSIONS

The new malleable probe achieved rapid freezing to clinically relevant levels in up to 5-mm-thick tissue. Both probes maintained their performance under a wide range of thermal loads.

Evaluation of a Novel Cryoablation System: In vitro Testing of Heat Capacity and Freezing Temperatures

Objective

Cryoablation has been used to ablate cardiac tissue for decades and has been shown to be able to replace incisions in the surgical treatment of atrial fibrillation. This in vitro study evaluates the performance of a novel cryoprobe and compares it with existing commercially available devices.

Methods

A new malleable 10-cm aluminum cryoprobe was compared with a rigid 3.5-cm copper linear probe using in vitro testing to evaluate performances under different thermal loads and with different tissue thicknesses. Radial dimensions of ice formation were measured in each water bath by a high-precision laser 2 minutes after the onset of cooling. Probe-surface temperatures were recorded by thermocouples. Tissue temperature was measured at depths of 4 mm and 5 mm from the probe-tissue interface. Time to reach a tissue temperature of −20°C was recorded.

Results

Ice formation increased significantly with lower water-bath temperatures (P < 0.001). Width and depth of ice formation were significantly less for the rigid linear probe (P < 0.012 and P < 0.001, respectively). There was no difference between the probes in the maximal negative temperature reached under different thermal loads or at different tissue depths. The malleable probe achieved significantly lower temperatures at the proximal compared with the distal end (–61.7°C vs −55.0°C, respectively; P < 0.001). A tissue temperature of −20°C was reached earlier at 4 mm than at 5 mm (P < 0.001) and was achieved significantly faster with the 3011 Maze Linear probe (P < 0.021).

Conclusions

The new malleable probe achieved rapid freezing to clinically relevant levels in up to 5-mm–thick tissue. Both probes maintained their performance under a wide range of thermal loads.

Vitamin D(3) cryosensitization increases prostate cancer susceptibility to cryoablation via mitochondrial-mediated apoptosis and necrosis

OBJECTIVES

To investigate the effect and molecular mechanisms of action of Vitamin D(3) (VD(3) ) as a neo-adjunctive agent before cryosurgery in an effort to increase treatment efficacy for prostate cancer (CaP). To eliminate the potential for disease recurrence that exists at the periphery of the freeze lesion, where temperatures may be insufficient to destroy both androgen-sensitive (AS) and androgen-insensitive (AI) CaP.

METHODS

Human CaP cells, LNCaP, were each genetically altered to express the AS and AI phenotypes and subjected to VD(3) treatment and freezing in an in vitro and tissue-engineered model. Cell viability, caspase inhibitor and western blot studies were used to determine the basis of the different responses of AI and AS cells to VD(3) cryosensitization.

RESULTS

VD(3) was found to be a highly effective cryosensitizer, resulting in a >50% overall increase in cell death after -15 °C freezing. Fluorescence microscopy, western blot analysis and caspase protease assays confirmed that the increased activation of apoptosis was modulated through a mitochondrial-mediated pathway. Caspase inhibition studies showed that apoptosis played an integral role in cell death, with VD(3) cryosensitivation-induced apoptotic events responsible for >30% of the overall cell death after -15 °C freezing.

CONCLUSIONS

The present study suggests that the use of VD(3) as a cryosensitizer increases cryoablation efficacy through the increased activity of apoptosis as well as through necrosis. The data show that through VD(3) treatment the overall level of AI CaP cell tolerance to freezing is reduced to a level similar to that of AS CaP. VD(3) pre-treatment in conjunction with cryoablation may increase treatment efficacy and reduce disease recurrence for CaP patients.

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.

Synthesis and characterization of thermally responsive Pluronic F127-chitosan nanocapsules for controlled release and intracellular delivery of small molecules

In this study, we synthesized empty core-shell structured nanocapsules of Pluronic F127 and chitosan and characterized the thermal responsiveness of the nanocapsules in size and wall-permeability. Moreover, we determined the feasibility of using the nanocapsules to encapsulate small molecules for temperature-controlled release and intracellular delivery. The nanocapsules are ∼37 nm at 37 °C and expand to ∼240 nm when cooled to 4 °C in aqueous solutions, exhibiting >200 times change in volume. Moreover, the permeability of the nanocapsule wall is high at 4 °C (when the nanocapsules are swollen), allowing free diffusion of small molecules (ethidium bromide, MW = 394.3 Da) across the wall, while at 37 °C (when the nanocapsules are swollen), the wall-permeability is so low that the small molecules can be effectively withheld in the nanocapsule for hours. As a result of their thermal responsiveness in size and wall-permeability, the nanocapsules are capable of encapsulating the small molecules for temperature-controlled release and intracellular delivery into the cytosol of both cancerous (MCF-7) and noncancerous (C3H10T1/2) mammalian cells. The cancerous cells were found to take up the nanocapsules much faster than the noncancerous cells during 45 min incubation at 37 °C. Moreover, toxicity of the nanocapsules as a delivery vehicle was found to be negligible. The Pluronic F127-chitosan nanocapsules should be very useful for encapsulating small therapeutic agents to treat diseases particularly when it is combined with cryotherapy where the process of cooling and heating between 37 °C and hypothermic temperatures is naturally done.

Cryoablation: mechanism of action and devices

Cryoablation refers to all methods of destroying tissue by freezing. Cryoablation causes cellular damage, death, and necrosis of tissues by direct mechanisms, which cause cold-induced injury to cells, and indirect mechanisms, which cause changes to the cellular microenvironment and impair tissue viability. Cellular injury, both indirect and direct, can be influenced by four factors: cooling rate, target temperature, time at target temperature, and thawing rate. In this review, the authors describe the mechanisms of cellular injury that occur with cryoablation, the major advantages and disadvantages of cryoablation compared with other thermal ablation techniques, and the current commercially available cryoablation ablation systems.

Integrin involvement in freeze resistance of androgen-insensitive prostate cancer

Cryoablation has emerged as a primary therapy to treat prostate cancer. While effective, the assumption that freezing serves as a ubiquitous lethal stress is challenged by clinical experience and experimental evidence demonstrating time-temperature related cell death dependence. The age-related transformation from an androgen-sensitive (AS) to an androgen-insensitive (AI) phenotype is a major challenge in the management of prostate cancer. AI cells exhibit morphological changes and treatment resistance to many therapies. Since this resistance has been linked with α6β4 integrin overexpression as a result of androgen receptor (AR) loss, we investigated whether α6β4 integrin expression, as a result AR loss, contributes to the reported increased freeze tolerance of AI prostate cancer. A series of studies using AS (LNCaP LP and PC-3 AR) and AI (LNCaP HP and PC-3) cell lines were designed to investigate the cellular mechanisms contributing to variations in freezing response. Investigation into α6β4 integrin expression revealed that AI cell lines overexpressed this protein, thereby altering morphological characteristics and increasing adhesion characteristics. Molecular investigations revealed a significant decrease in caspase 8, 9, and 3 levels AI cells following freezing. Inhibition of α6β4 integrin resulted in increased caspase activity following freezing (similar to AS cells) and enhanced cell death. These data demonstrate that AI cells show an increase in post-freeze susceptibility following inhibition of α6β4 integrin function. Further understanding the role of androgen-receptor related α6β4 integrin expression in prostate cancer cells responses to freezing might lead to novel options for neo-adjunctive treatments targeting the AR signaling pathway.

Effects of freezing on intratumoral drug transport

Efficacy of many novel therapeutic agents are impaired by hindered interstitial diffusion in tumor. In the context of overcoming this drug delivery barrier, a hypothesis was postulated that freeze/thaw (F/T) may induce favorable changes of tumor tissue microstructure to facilitate the interstitial diffusion. This hypothesis may also be relevant to develop a mechanistically derived chemotherapeutic strategy for cryo-treated tumors. In the present study, this hypothesis was tested by characterizing the effects of F/T on the interstitial diffusion using an in vitro engineered tumor model (ET). The diffusion coefficients of FITC-labeled dextran was measured within the frozen/thawed and unfrozen ETs. The results showed that the diffusion coefficients increased after F/T but the extent of increase was dependent on the size of dextran. This implies that the combination of cryosurgery and chemotherapy should be designed considering the biophysical changes of tissues after freeze/thaw and the diffusion characteristics of drug molecules.

Freezing-Assisted Intracellular Drug Delivery to Multidrug Resistant Cancer Cells

The efficacy of chemotherapy is significantly impaired by the multidrug resistance (MDR) of cancer cells. The mechanism of MDR is associated with the overexpression of certain adenosine triphosphate-binding cassette protein transporters in plasma membranes, which actively pump out cytotoxic drugs from the intracellular space. In this study, we tested a hypothesis that freezing and thawing (F/T) may enhance intracellular drug delivery to MDR cancer cells via F/T-induced denaturation of MDR-associated proteins and/or membrane permeabilization. After a human MDR cancer cell line (NCI/ADR-RES) was exposed to several F/T conditions, its cellular drug uptake was quantified by a fluorescent calcein assay using calcein as a model drug. After F/T to −20°C, the intracellular uptake of calcein increased by 70.1% (n=5, P=0.0004). It further increased to 118% as NCI/ADR-RES cells were frozen/thawed to −40°C (n=3, P=0.009). These results support the hypothesis, and possible mechanisms of F/T-enhanced intracellular drug delivery were proposed and discussed.

Cryosurgical technique: assessment of the fundamental variables using human prostate cancer model systems

Cryosurgery offers a promising therapeutic alternative for the treatment of prostate cancer. While often successful, complete cryoablation of cancerous tissues sometimes fails due to technical challenges. Factors such as the end temperature, cooling rate, duration of the freezing episode, and repetition of the freezing cycle have been reported to influence cryosurgical outcome. Accordingly, we investigated the effects of these variables in an in vitro prostate cancer model. Human prostate cancer PC-3 and LNCaP cultures were exposed to a range of sub-zero temperatures (-5 to -40 degrees C), and cells were thawed followed by return to 37 degrees C. Post-thaw viability was assessed using a variety of fluorescent probes including alamarBlue (metabolic activity), calceinAM (membrane integrity), and propidium iodide (necrosis). Freeze duration following ice nucleation was investigated using single and double freezing cycles (5, 10, and 20 min). The results demonstrated that lower freezing temperatures yielded greater cell death, and that LNCaP cells were more susceptible to freezing than PC-3 cells. At -15 degrees C, PC-3 yielded approximately 55% viability versus approximately 20% viability for LNCaP. Double freezing cycles were found to be more than twice as destructive versus a single freeze-thaw cycle. Both cell types experienced increased cell death when exposed to freezing temperatures for longer durations. When thawing rates were considered, passive (slower) thawing following freezing yielded greater cell death than active (faster) thawing. A 20% difference in viability between passive and active thawing was observed for PC-3 for a 10 min freeze. Finally, the results demonstrate that just reaching -40 degrees C in vitro may not be sufficient to obtain complete cell death. The data support the use of extended freeze times, multiple freeze-thaw cycles, and passive thawing to provide maximum cell destruction.

Histopathological study of breast cancer and normal breast tissue after magnetic resonance-guided cryotherapy ablation

BACKGROUND

Cryotherapy ablation is a minimally invasive procedure being investigated as an alternative to conventional surgery. There are few reports in breast cancer.

AIM

Evaluate the histopathology of tumoral and normal breast tissue after cryotherapy.

METHODS

Eleven patients with clinically <2.0cm and ultrasound visible tumors were studied. Invasive carcinoma was documented by preoperative mammography, magnetic resonance imaging and biopsies. Cryotherapy needles were inserted in the tumor under magnetic resonance guidance and deep freezed with a CRYO-HIT TM System-3. Lumpectomy was performed within 4-5 weeks following cryoablation and submitted for pathological examination including immunostaining of keratins.

RESULTS

The tumoral response after cryoablation was variable. In 4 cases there was no viable invasive carcinoma left and focal DCIS only in 2. In 6 cases, residual invasive carcinoma of various size was present with DCIS inside or outside the cryozone. One case could not be evaluated because the cryozone was adjacent to the tumor due to technical problems. Histologically, the normal breast parenchyma of the cryozone showed dense fibrosis, fat necrosis, xanthogranulomatous reaction, endovascular fibrosis and haemorrhages in all cases. The positive immunostaining of keratins revealed remnants of cytoskeleton of carcinomatous cells in the necrotic areas without any viable tumoral cells on routine stains. Skin ulceration and/or necrosis were observed in five patients.

CONCLUSIONS

Cryotherapy allows tumor destruction of variable extent in breast carcinomas <2.0cm in diameter. Immunostaining of keratins is useful to identify cytoskeleton remnants of tumor cells in devitalized areas.

Development of a tissue engineered human prostate tumor equivalent for use in the evaluation of cryoablative techniques

The study of the effectiveness of cryotherapy as a curative treatment for prostate cancer has often relied on the use of either in vitro cell culture monolayers or animal models. While the data gleaned from these studies have been valuable, each model has inherent limitations. In order to bridge the gap between in vitro studies and clinical applications, we developed a 3-dimensional, tissue engineered human prostate cancer model to simulate and assess the effects of cryotherapy and adjunctive treatments on cell viability and activation of cell death pathways throughout the thermally variable freeze zone. Human prostate cancer cells (PC3) were seeded into collagen based matrices and cryolesions were generated using an Oncura SeedNet Gold cryosurgical device with 17-gauge cryoprobes. Analyses revealed widespread necrosis diminishing towards the edge of the freeze zone, and a time-dependent wave of apoptosis starting as early as 1 hr post-thaw at low temperatures (< -40 degrees C) and moving toward the periphery (-20 degrees C) as recovery times reached 12 and 24 hr. Distal to the -10 degrees C isotherm, minimal cell death was apparent (< 20%) over controls. The adjunctive use of chemotherapeutic agents in conjunction with cryosurgery displayed a similar induction of cell death cascades, but with the zone of cryodestruction extending approximately 10 to 15 degrees C further into the freeze zone periphery. By providing an extracellular environment and a matrix to minimize innate variables, the tissue engineered model yielded a more in vivo-like, tumor-like environment supportive of a deeper understanding of the specific biological responses of cancer cells/tumors to cryotherapeutic intervention.

Cryoablation of renal cancer: variables involved in freezing-induced cell death

The detection of renal tumors has increased significantly over recent years resulting in a greater demand for novel, minimally invasive techniques. Cryoablation has emerged as a valuable treatment modality for the management of renal cancer. In an effort to detail the effects of freezing in renal cancer, the human renal cancer (RCC) cell line, 786-O, was evaluated in vitro. 786-O cells were exposed to a range of freezing temperatures from -5 to -40 degrees C and compared to non-frozen controls. The data show that freezing to -5 degrees C did not affect 786-O cell viability, while -10 degrees C, -15 degrees C, and -20 degrees C results in a significant loss of viability (23, 70, and 91%, respectively). A complete loss of cell viability was evident at temperatures of -25 degrees C and colder. Following this analysis, variables involved in the success of cryoablation were investigated. For each of the temperatures tested, extended freeze hold times and passive thawing rates resulted in more extensive cell damage. Additionally, a double freeze-thaw cycle significantly increased cell death compared to a single cycle (62% vs. 22% at -10 degrees C; 89% vs. 63% at -15 degrees C, respectively). While these variables play an important part in the effective application of cryoablation, a molecular understanding of the cell death involved is critical to improving efficacy. Apoptotic inhibition afforded 12% (-10 degrees C), 25% (-15 degrees C), and 11% (-20 degrees C) protection following freezing. Using fluorescence microscopy analysis, the results demonstrated that apoptosis peaked at six hours post-thaw. Next, apoptotic initiating agents including 5-FU and resveratrol (RVT) applied prior to freezing exposure resulted in a significant increase in cell death compared to either application alone. Importantly, the combination of RVT and freezing was noticeably less effective when applied to normal renal cells. The results herein demonstrate the efficacy of freezing and describe a novel therapeutic model for the treatment of renal cancer that may distinguish between cancer and normal cells.

Targeted induction of apoptosis via TRAIL and cryoablation: a novel strategy for the treatment of prostate cancer

Adjuvant therapies contribute to the successful treatment of cancer. Our previous reports have shown that combining cryoablation with cytotoxic agents enhances cell death. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a cytotoxic agent that preferentially induces apoptosis in a variety of human cancer cells. Human prostate cancer cells (PC-3) are resistant to many cytodestructive agents, including cryoablation and TRAIL. Here, we evaluated the effects of TRAIL combined with cryoablation on PC-3 and normal prostate (RWPE-1) cell death. Exposure of PC-3 cells to freezing (-10 degrees C) or TRAIL (500 ng/ml) results in minimal cell death, whereas a complete loss of viability is observed with the simultaneous combination. The synergistic effect was found to be due to a marked increase in apoptosis. Western blot analysis revealed a significant level of caspase-8 and -3 cleavage between 12 and 24 h post-exposure. Caspase activation assays provided similar results and also indicated a role for caspase-9. Inhibitors to caspase-8 and -9 along with a pan-caspase inhibitor were incorporated to determine which pathway was necessary for the combined efficacy. Inhibition of caspase-8 significantly blocked the combination-induced cell death compared to cells that did not receive the inhibitor (63% compared to 10% viable). The addition of the caspase-9 inhibitor resulted in only a minimal protection. Importantly, the combination was not effective when applied to normal prostate cells. The results describe a novel therapeutic model for the treatment of prostate cancer and provide support for future in vivo studies.

Papel da criocirurgia no tratamento das neoplasias cutâneas do segmento cabeça e pescoço: análise de 1900 casos

OBJETIVO: Demonstrar a experiência dos autores na utilização da criocirurgia como tratamento de lesões benignas e malignas da pele e mucosa no segmento cabeça e pescoço. MÉTODO: Os autores realizam um estudo retrospectivo multicêntrico de 1900 casos de pacientes portadores de neoplasias benignas e malignas da cabeça e do pescoço, atendidos e tratados no Centro de Oncologia do Hospital Universitário Oswaldo Cruz (CEON/HUOC/UPE), Hospital de Câncer de Pernambuco (HCP) e clínica privada, no período de abril de 1977 a abril de 2002 (25 anos). Comparam, ainda, os dados obtidos com a revisão bibliográfica realizada, bem como sua experiência pessoal na utilização de tal modalidade terapêutica. RESULTADOS: Do total de pacientes, 57,9% eram do sexo masculino e a quinta e sexta décadas de vida foram as mais frequentemente acometidas (58,9%). O Carcinoma basocelular foi o tipo histológico predominante (63,1% - 1200 casos), seguido dos hemangiomas (14,2% - 270 casos). O tempo médio de exposição das lesões ao nitrogênio líquido foi de 15 e 35 segundos, e o tempo médio de cicatrização de 14 e 21 dias para as lesões benignas e malignas respectivamente. CONCLUSÕES: A indicação da criocirurgia deve obedecer alguns critérios de avaliação como o aspecto macroscópico e tamanho da lesão, tipo histológico, localização, idade e perfil social de cada paciente. Quando indicada e executada corretamente, oferece idênticos índices de cura aos outros métodos terapêuticos convencionais.

"Finger-tip" cryotherapy probes: treatment of squamous and melanocytic conjunctival neoplasia

AIM

To describe the use of a new spatulated cryoprobe in treatment of conjunctival neoplasia.

METHODS

A new cryoprobe design was submitted to Mira, Inc resulting in new hand held probes capable of producing homogeneous freezing over large surface areas. The active surface of the small, medium, and large spatulated probes are 8.5 mm2, 25.2 mm2, and 70 mm2. End freezing reduces the possibility of inadvertent freezing of adjacent tissues (outside the targeted zone). In this series, the probes were employed to treat patients with squamous and melanocytic conjunctival neoplasia.

RESULTS

12 consecutive patients with malignant conjunctival neoplasia were treated with these new cryotherapy probes. Techniques of probe construction and clinical use are described. Cryoburns of the cornea, sclera, and conjunctiva were formed and recorded by digital photography. Ophthalmic examinations before and after surgery demonstrated that no acute intraocular or adnexal complications occurred. No loss of visual acuity could be attributed to this use of the cryoprobes.

CONCLUSION

"Finger-tip" cryoprobes were used to treat malignant conjunctival neoplasia (squamous and melanocytic). Probe design allowed for uniform freezing over large surface areas. This cryoprobe design appears to be ideal for treatment of conjunctival tumours.

Cryoablation and cryolocalization in the management of breast disease

Cryotechnology is currently used for both treatment and diagnosis of breast disease. Due to the natural analgesic effect of cold, cryoablation is potentially more patient-friendly than other technologies which raise tissue temperature. Freezing produces a predictable volume of necrosis and is easily observed and controlled during treatment. Recent studies have demonstrated that, as a primary therapy for breast fibroadenoma, cryoablation is safe and effective with durable results that can be reproduced in community practices. Certain barriers do exist before cryoablation, or any other in situ ablation, can become a standard therapy for the treatment of localized breast malignancy. Investigations are underway to refine patient selection criteria and develop valid confirmatory assays so that clinical trials can begin. Cryolocalization, which creates a well-delineated, palpable mass of frozen tissue encompassing a tumor, is a relatively new application of cold in medicine. This strategy promises to reduce positive margin rates during lumpectomy of non- or barely-palpable tumors. Finally, cryotechnology now also aids in the collection of tissue for histological analysis.