Cryosurgery for tumors

Cryoablation and Immunotherapy: An Enthralling Synergy for Cancer Treatment

As less invasive options for surgical tumor removal, minimally invasive ablative techniques have gained popularity. Several solid tumors are being treated with cryoablation, a non-heat-based ablation technique. Cryoablation data in comparison over time demonstrates better tumor response and faster recovery. Combining cryosurgery with other cancer therapies has been explored to improve the cancer-killing process. Cryoablation with the combination of immunotherapy, results in a robust and efficient attack on the cancer cells. This article focuses on investigating the ability of cryosurgery to create a strong antitumor response when combined with immunologic agents resulting in a synergetic effect. To achieve this objective, we combined cryosurgery with immunotherapy using Nivolumab and lpilimumab. Five clinical cases of lymph node, lung cancer, bone, and lung metastasis were followed and analyzed. In this series of patients, percutaneous cryoablation and addressing immunity agents were technically feasible. In the follow-ups, there appeared to be no radiological evidence of new tumor development.

A Fiber Optic Sensor for Monitoring the Spectral Alterations and Depth in Ex Vivo and In Vivo Cryosurgery

This article discusses how to monitor the freezing depth during cryotherapy using a fiber optic array sensor. The sensor was used to measure the backscattered and transmitted light from frozen and unfrozen ex vivo porcine tissue and in vivo human skin tissue (finger). The technique exploited the variations in optical diffusion properties of the frozen and unfrozen tissues to determine the extent of freezing. Ex vivo and in vivo measurements yielded comparable results, despite spectral variations attributable to the hemoglobin absorption peak in the human frozen and unfrozen tissues. However, because the spectral fingerprints of the freeze-thaw process in the ex vivo and in vivo experiments were similar, we could extrapolate the maximum depth of freezing. Therefore, this sensor has the potential to be utilized for monitoring cryosurgery in real time.

In-situ cryo-immune engineering of tumor microenvironment with cold-responsive nanotechnology for cancer immunotherapy

Cancer immunotherapy that deploys the host's immune system to recognize and attack tumors, is a promising strategy for cancer treatment. However, its efficacy is greatly restricted by the immunosuppressive (i.e., immunologically cold) tumor microenvironment (TME). Here, we report an in-situ cryo-immune engineering (ICIE) strategy for turning the TME from immunologically "cold" into "hot". In particular, after the ICIE treatment, the ratio of the CD8+ cytotoxic T cells to the immunosuppressive regulatory T cells is increased by more than 100 times in not only the primary tumors with cryosurgery but also distant tumors without freezing. This is achieved by combining cryosurgery that causes "frostbite" of tumor with cold-responsive nanoparticles that not only target tumor but also rapidly release both anticancer drug and PD-L1 silencing siRNA specifically into the cytosol upon cryosurgery. This ICIE treatment leads to potent immunogenic cell death, which promotes maturation of dendritic cells and activation of CD8+ cytotoxic T cells as well as memory T cells to kill not only primary but also distant/metastatic breast tumors in female mice (i.e., the abscopal effect). Collectively, ICIE may enable an efficient and durable way to leverage the immune system for combating cancer and its metastasis.

Minimally Invasive Resection of Benign Osseous Tumors of the Spinal Column: 10 Years' Experience and Long-Term Outcomes of a Specialized Center

Background and Objectives: Benign osseous tumors of the spinal column comprise about 10% of all spinal tumors and are rare cause for surgery. However, these tumors pose various management challenges and conventional surgery may be associated with significant morbidity. Previous reports on minimally invasive resection of these lesions are rare. We report a series of patients managed by total resection of benign osseous spine tumors using MIS techniques. Surgical decisions and technical considerations are discussed. Materials and Methods: A retrospective evaluation of prospectively collected data of patients who underwent minimally invasive surgery for removal of benign osseous vertebral tumors. Demographic, clinical and radiographic features, operative details and final pathological reports were summarized. Primary outcomes were completeness of tumor resection and pain relief assessed by VAS for back and leg pain. Secondary outcome measures were recurrence of tumor on repeat post-operative MRI and postoperative unstable deformity on standing scoliosis X-rays. Results: This series included 32 cases of primary osseous spine tumors resected by minimally invasive techniques. There were 17 males and 15 females aged 5-68 years (mean 23.3). The follow-up period was 8-90 months (mean 32 months) and the preoperative symptoms duration was 9-96 months. Axial spinal pain was the presenting symptom in all the patients. Five patients also complained about radicular pain and four patients had antalgic scoliosis. The tumor involved the thoracic spine in 12 cases, the lumbar segment in 11, the cervical in 5 and the sacral area in 4 cases. Complete tumor removal was performed in all patients. No procedure-related complications were encountered. Histopathology showed osteoid osteoma in 24 patients, osteoblastoma in 5 patients, and fibrous dysplasia, fibroadenoma and eosinophilic granuloma in one case each. All patients experienced significant pain relief after surgery, and had stopped pain medications by 12 months postoperatively. No patient suffered from tumor recurrence or spinal deformity. Conclusions: Minimally invasive surgery is feasible for total removal of selected benign vertebral tumors and may have some advantages over conventional surgical techniques.

M, Muralidoss H, Kumar SP, Krishnan M. Liquid Nitrogen Cryotherapy in the Management of Hemangioma of the Tongue

Recurrent bleeding due to mild trauma, tongue biting, poor oral hygiene, and expansion of the lesions causing difficulty in chewing, swallowing, or speaking is common sequelae of vascular lesions of the tongue. Cryosurgery is a technique for destroying lesions by the rapid freezing method. The necrotic tissue that results is allowed to slough naturally after the lesion is frozen. Cryosurgery has been utilized in the medical and dentistry field to treat many lesions as it is successful and easy to perform. It has a number of advantages, including ease of use, minimal infection rate, and no bleeding intraoperatively. This report presents a case of a 15-year-old female patient with a hemangiomatous lesion on the tongue that was successfully treated by cryosurgery using a liquid nitrogen spray. The patient demonstrated complete resolution of the lesion with good wound healing during the one-year follow-up period.

An In Vitro Investigation into Cryoablation and Adjunctive Cryoablation/Chemotherapy Combination Therapy for the Treatment of Pancreatic Cancer Using the PANC-1 Cell Line

As the incidence of pancreatic ductal adenocarcinoma (PDAC) continues to grow, so does the need for new strategies for treatment. One such area being evaluated is cryoablation. While promising, studies remain limited and questions surrounding basic dosing (minimal lethal temperature) coupled with technological issues associated with accessing PDAC tumors and tumor proximity to vasculature and bile ducts, among others, have limited the use of cryoablation. Additionally, as chemotherapy remains the first-line of attack for PDAC, there is limited information on the impact of combining freezing with chemotherapy. As such, this study investigated the in vitro response of a PDAC cell line to freezing, chemotherapy, and the combination of chemotherapy pre-treatment and freezing. PANC-1 cells and PANC-1 tumor models were exposed to cryoablation (freezing insult) and compared to non-frozen controls. Additionally, PANC-1 cells were exposed to varying sub-clinical doses of gemcitabine or oxaliplatin alone and in combination with freezing. The results show that freezing to −10 °C did not affect viability, whereas −15 °C and −20 °C resulted in a reduction in 1 day post-freeze viability to 85% and 20%, respectively, though both recovered to controls by day 7. A complete cell loss was found following a single freeze below −25 °C. The combination of 100 nM gemcitabine (1.1 mg/m2) pre-treatment and a single freeze at −15 °C resulted in near-complete cell death (<5% survival) over the 7-day assessment interval. The combination of 8.8 µM oxaliplatin (130 mg/m2) pre-treatment and a single −15 °C freeze resulted in a similar trend of increased PANC-1 cell death. In summary, these in vitro results suggest that freezing alone to temperatures in the range of −25 °C results in a high degree of PDAC destruction. Further, the data support a potential combinatorial chemo/cryo-therapeutic strategy for the treatment of PDAC. These results suggest that a reduction in chemotherapeutic dose may be possible when offered in combination with freezing for the treatment of PDAC.

Cellulose Nanocrystals Facilitate Needle-like Ice Crystal Growth and Modulate Molecular Targeted Ice Crystal Nucleation

Ice nucleators are of crucial and important implications in various fields including chemistry, climate, agriculture, and cryobiology. However, the complicated extract and biocompatibility of ice nucleators remain unresolved, and the mechanism of ice nucleation remains largely unknown. Herein, we show that natural nanocrystalline cellulose materials possess special properties to enhance ice nucleation and facilitate needle-like ice crystal growth. We reveal the molecular level mechanism that the efficient exposure of cellulose hydroxyl groups on (-110) surface leads to faster nucleation of water. We further design chitosan-decorated cellulose nanocrystals to accomplish molecular cryoablation in CD 44 high-expression cells; the cell viability shows more than ∼10 times decrease compared to cryoablation alone and does not show evident systematic toxicity. Collectively, our findings also offer improved knowledge in molecular level ice nucleation, which may benefit multiple research communities and disciplines.

Full-Endoscopic Resection of Osteoid Osteoma in the Thoracic Spine: A Case Report

Common symptoms such as axial pain or nocturnal pain, associated with warning signs that are often worrisome in addition to nonspecific radiological findings, can characterize benign lesions in the spine, and osteoid osteoma is among them. We describe here a clinical case of a pediatric patient with an expansive bone lesion in the thoracic spine discovered after investigation for thoracic pain, mainly at night, which, despite a good response to simple analgesics, evolved in the short term with global spinal deformity. After a multidisciplinary evaluation, she underwent surgical resection using a pioneering endoscopic technique that allowed the definitive anatomopathological diagnosis of osteoid osteoma and guaranteeing very satisfactory treatment and evolution. Although there are already several therapeutic techniques described and with good results in specific cases of osteoid osteomas and other benign neoplastic lesions of the spine, full-endoscopic resection appears as an innovative and potentially promising option for diagnosis and treatment, especially since it is a safe, effective, and not too morbid intervention.

Water-transport and intracellular ice formation of human adipose-derived stem cells during freezing

The key to optimizing the cryopreservation strategy of human adipose-derived stem cells (hADSCs) is to identify the biophysical characteristics during freezing. Systematic freezing experiments were conducted under a cryo-microscope system to investigate the cryoinjury mechanism for hADSCs at different cooling rates. By simultaneously fitting morphological change data to the water-transport equation at 5, 10 and 20 °C/min, the plasma membrane hydraulic conductivity, L_pg, and activation energy, E_Lp, were determined. Moreover, the optimal cooling rate was also predicted by using mathematical model methods. Additionally, the surface-catalyzed nucleation (SCN) parameters were calculated by fitting in numerical models, Ω₀^SCN and k₀^SCN were determined at cooling rates of 30, 45 and 60 °C/min. These results may provide potential application value for cryopreservation of hADSCs.

Liquid Metal Hybrid Platform-Mediated Ice-Fire Dual Noninvasive Conformable Melanoma Therapy

Cryoablation and photothermal therapy are anticancer therapeutic strategies that destroy tumors by external energy intervention of achieving extremely low temperature and very high temperature in a short time. Compared to traditional surgical resection, radiotherapy, and chemotherapy, they have the advantages of being minimally invasive and having less side effects. However, single cryoablation or photothermal therapy itself has limited therapeutic accuracy, which greatly restricts its clinical application. There is still a common phenomenon that the energy transport at the tumor target site cannot be accurately controlled in space and time dimensions, resulting in limited thermal effect and difficulty to form a conformable treatment area, which will result in low targeted killing efficiency, and tumor cells will become residual and undergo metastasis and recurrence. Herein, a multimodal therapy of cryoablation combined with photothermal therapy was proposed. To further enhance the therapeutic performance, a liquid metal hybrid platform, which is composed of a high-thermal-conductivity liquid metal paste and high-photothermal-conversion-efficiency liquid metal nanoparticles, is mediated for cryoablation and photothermal therapy. Cold and heat synergistic effects are realized through this multimodal therapy. Due to the liquid metal hybrid platform, enhanced antitumor efficacy is achieved in vitro and in vivo. More importantly, the liquid metal hybrid platform-mediated dual therapy is totally noninvasive and does not show obvious systemic toxicity. Collectively, this study has first realized ice (cryoablation)-fire (photothermal therapy) dual noninvasive therapy by one liquid metal platform and demonstrated superior antitumor effect for melanoma treatment. This work explores a new promising multimodal cancer therapy strategy based on the liquid metal platform, which has great potential application in cancer treatment in the future.

Utility of Motor and Somatosensory Evoked Potentials for Neural Thermoprotection in Ablations of Musculoskeletal Tumors

PURPOSE

To characterize the utility of monitoring transcranial electrical motor evoked potentials (TCeMEPs) and somatosensory evoked potentials (SSEPs) for neural thermoprotection during musculoskeletal tumor ablations.

MATERIALS AND METHODS

Retrospective review of 29 patients (16 male; median age, 46 y; range, 7-77 y) who underwent musculoskeletal tumor radiofrequency ablation (n = 8) or cryoablation (n = 22) with intraprocedural TCeMEP and SSEP monitoring was performed. The most common tumor histologies were osteoid osteoma (n = 6), venous malformation (n = 5), sarcoma (n = 5), renal cell carcinoma (n = 4), and non-small-cell lung cancer (n = 3). The most common tumor sites were spine (n = 22) and lower extremities (n = 4). Abnormal TCeMEP change was defined by 100-V increase above baseline threshold activation for a given myotome; abnormal SSEP change was defined by 60% reduction in baseline amplitude and/or 10% increase in latency.

RESULTS

Abnormal changes in TCeMEP (n = 9; 30%) and/or SSEP (n = 5; 17%) occurred in 12 procedures (40%) and did not recover in 5 patients. Patients with unchanged TCeMEP/SSEP activities throughout the procedure (n = 18) did not have motor or sensory symptoms after the procedure; 3 (60%) with unrecovered activity changes and 2 (29%) with transient activity changes had new motor (n = 1) or sensory (n = 4) symptoms. Relative risk for neurologic sequelae for patients with unrecovered TCeMEP/SSEP changes vs those with transient or no changes was 7.50 (95% confidence interval, 1.66-33.9; P = .009).

CONCLUSIONS

Abnormal activity changes of TCeMEP or SSEP during percutaneous ablative procedures correlate with postprocedural neurologic sequelae.

Cryoablation-activated enhanced nanodoxorubicin release for the therapy of chemoresistant mammary cancer stem-like cells

Anticancer nanodoxorubicin with targeting ability, thermal responsive and pH sensitive characteristic is fabricated. Nanodrug could realize controllable and enhanced drug release when cryoablation is applied at the target tumor site.

Clove Oil Delays Rather Than Prevents Scur/Horn Growth in Dairy Cattle

The objective of this study was to evaluate if administration of clove oil prevents scur/horn growth in dairy cattle long term. At approximately 4 days of age, calves had one of four treatments assigned to each horn bud: (1) clove oil administered subcutaneously under the horn bud (CLOV, n = 132); (2) cautery disbudded and the horn bud removed (BUDOFF, n = 126); (3) cautery disbudded and the horn bud tissue left intact (BUDON, n = 129); (4) a liquid nitrogen filled probe applied to the horn bud area (CRYO, n = 131). At approximately 16 months of age, all cattle were checked for scur or horn development. A sub-set of scurs/horns from the CLOV cattle were removed to evaluate tissue and structural development. In total, 5% of CLOV buds developed into horns and 63% into scurs; 10% of the scurs looked like normally developed horns but they were not attached to the skull. Cautery disbudding prevented scur and horn development in cattle when the horn bud tissue was removed, but some scur growth was observed in the BUDON treatment. CRYO was 100% ineffective at preventing scur/horn growth. Injecting clove oil under the horn bud appeared to delay horn development, but not prevent it, when administered to 4 day old dairy calves.

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.

Dose Escalation of Vitamin D3 Yields Similar Cryosurgical Outcome to Single Dose Exposure in a Prostate Cancer Model

Vitamin D₃ (VD₃) is an effective adjunctive agent, enhancing the destructive effects of freezing in prostate cancer cryoablation studies. We investigated whether dose escalation of VD₃ over several weeks, to model the increase in physiological VD₃ levels if an oral supplement were prescribed, would be as or more effective than a single treatment 1 to 2 days prior to freezing. PC-3 cells in log phase growth to model aggressive, highly metabolically active prostate cancer were exposed to a gradually increasing dose of VD₃ to a final dose of 80 nM over a 4-week period, maintained for 2 weeks at 80 nM, and then exposed to mild sublethal freezing temperatures. Results demonstrate that both acute 24-hour exposure to 80 nM VD₃ and dose escalation resulted in enhanced cell death following freezing at −15°C or colder, with no significant differences between the 2 exposure regimes. Apoptotic analysis within the initial 24-hour period postfreeze revealed that VD₃ treatment induced both caspase 8- and 9-mediated cell death, most notably in caspase 8 at 8-hour postfreeze. These results indicate that both the intrinsic and extrinsic apoptotic pathways are involved in VD₃ sensitization prior to freezing. Additionally, both acute and gradual dose escalation regimes of VD₃ exposure increase prostate cancer cell sensitivity to mild freezing. Importantly, this study expands upon previous reports and suggests that the combination of VD₃ and freezing may offer an effective treatment for both slow growth and highly aggressive prostate cancers.

Enhanced cancer therapy with cold-controlled drug release and photothermal warming enabled by one nanoplatform

Stimuli-responsive nanoparticles hold great promise for drug delivery to improve the safety and efficacy of cancer therapy. One of the most investigated stimuli-responsive strategies is to induce drug release by heating with laser, ultrasound, or electromagnetic field. More recently, cryosurgery (also called cryotherapy and cryoablation), destruction of diseased tissues by first cooling/freezing and then warming back, has been used to treat various diseases including cancer in the clinic. Here we developed a cold-responsive nanoparticle for controlled drug release as a result of the irreversible disassembly of the nanoparticle when cooled to below ∼10 °C. Furthermore, this nanoparticle can be used to generate localized heating under near infrared (NIR) laser irradiation, which can facilitate the warming process after cooling/freezing during cryosurgery. Indeed, the combination of this cold-responsive nanoparticle with ice cooling and NIR laser irradiation can greatly augment cancer destruction both in vitro and in vivo with no evident systemic toxicity.

Immunological effect of local ablation combined with immunotherapy on solid malignancies

Recent comprehensive investigations clarified that immune microenvironment surrounding tumor cells are deeply involved in tumor progression, metastasis, and response to treatment. Furthermore, several immunotherapeutic trials have achieved successful results, and the immunotherapeutic agents are available in clinical practice. To enhance their demonstrated efficacy, combination of immunotherapy and ablation has begun to emerge. Local ablations have considerable advantages as an alternative therapeutic option, especially its minimal invasiveness. In addition, local ablations have shown immune-regulatory effect in preclinical and clinical studies. Although the corresponding mechanisms are still unclear, the local ablations combined with immunotherapy have been suggested in the treatment of several solid malignancies. This article aims to review the published data on the immune-regulatory effects of local ablations including stereotactic body radiotherapy, cryoablation, radiofrequency ablation, and high-intensity-focused ultrasound. We also discuss the value of local ablations combined with immunotherapy. Local ablations have the potential to improve future patient outcomes; however, the effectiveness and safety of local ablations combined with immunotherapy should be further investigated.

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.

Benign Spine Lesions: Advances in Techniques for Minimally Invasive Percutaneous Treatment

Minimally invasive percutaneous imaging-guided techniques have been shown to be safe and effective for the treatment of benign tumors of the spine. Techniques available include a variety of tumor ablation technologies, including radiofrequency ablation, cryoablation, microwave ablation, alcohol ablation, and laser photocoagulation. Vertebral augmentation may be performed after ablation as part of the same procedure for fracture stabilization or prevention. Typically, the treatment goal in benign spine lesions is definitive cure. Painful benign spine lesions commonly encountered in daily practice include osteoid osteoma, osteoblastoma, vertebral hemangioma, aneurysmal bone cyst, Paget disease, and subacute/chronic Schmorl node. This review discusses the most recent advancement and use of minimally invasive percutaneous therapeutic options for the management of benign spine lesions.

Circumferential cryoablation in a strictured esophagus: a feasibility and dose-finding study in a porcine model after inducing stenosis by endoscopic mucosal resection

In the treatment of early esophageal Barrett's neoplasia, radiofrequency ablation may be hindered by stenosis due to prior endoscopic resection (ER). The flexible balloon-based circumferential CryoBalloon Ablation System (CBAS) may overcome this problem by the conformability of the compliant balloon which might enable circumferential cryoablation in a stenosis. The aim of the current study was to evaluate the feasibility of the CBAS as well as the dose-response effect of cryoablation in a strictured esophagus model. In six pigs, a stenosis was induced by ER (3 cm in length, 75% of circumference) in the proximal, mid, and distal esophagus. After 28 days, cryoablation with the CBAS was performed, with the length of ablation time (6, 8, or 10 seconds) randomly assigned per stricture location within the esophagus. Four days post-ablation, the esophagi were harvested for histopathological assessment of the percentage of the total circumference affected by cryoablation and the maximum depth of necrosis. At 28 days, all 18 ER areas had transformed into strictures with ±50% of its original diameter remaining. In 9 of 18 strictures, more than one attempt for cryoablation was necessary due to displacement of the balloon. Histopathological evaluation showed a wide range in circumferential uniformity (0-100%) and maximum necrosis depth (epithelium to external proper muscle layer) of cryoablation, both independent of ablation times. Deepest ablation effects were seen at the center of the resection-induced scar. This first generation CryoBalloon Focal Ablation System was not feasible for ablation within severe stenoses, since it results in inconsistent circumferential uniformity of cryoablation with subsequent differences in depth of ablation. Further research with a next generation CBAS in a more realistic stricture model is warranted.

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.

An efficient technique for estimating the two-dimensional temperature distributions around multiple cryo-surgical probes based on combining contributions of unit circles

This study presents an efficient, fast and accurate method for estimating the two-dimensional temperature distributions around multiple cryo-surgical probes. The identical probes are inserted into the same depth and are operated simultaneously and uniformly. The first step in this method involves numerical derivation of the temporal performance data of a single probe, embedded in a semi-infinite, tissue-like medium. The results of this derivation are approximated by algebraic expressions that form the basis for computing the temperature distributions of multiple embedded probes by combining the data of a single probe. Comparison of isothermal contours derived by this method to those computed numerically for a variety of geometrical cases, up to 15 inserted probes and 2-10 min times of operation, yielded excellent results. Since this technique obviates the solution of the differential equations of multiple probes, the computational time required for a particular case is several orders of magnitude shorter than that needed for obtaining the full numerical solution. Blood perfusion and metabolic heat generation rates are demonstrated to inhibit the advancement of isothermal fronts. Application of this method will significantly shorten computational times without compromising the accuracy of the results. It may also facilitate expeditious consideration of the advantages of different modes of operation and the number of inserted probes at the early design stage.

Features and Role of Minimally Invasive Palliative Procedures for Pain Management in Malignant Pelvic Diseases: A Review

Pain is a common and debilitating symptom in pelvic cancer diseases. Failure in controlling this pain through pharmacological approaches calls for employing multimodal management and invasive techniques. Various strategies are commonly used for this purpose, including palliative radiotherapy, epidural medications and intrathecal administration of analgesic and local anesthetic drugs with pumps, and neural or plexus blockade. This review focuses on the features of minimally invasive palliative procedures (MIPPs), such as radiofrequency ablation, laser-induced thermotherapy, cryoablation, irreversible electroporation, electrochemotherapy, microwave ablation, and cementoplasty as well as their role in palliation of cancer pelvic pain. Despite the evidence of effectiveness and safety of these interventions, there are still many barriers to accessing MIPPs, including the availability of trained staff, the lack of precise criteria of indication, and the high costs.

Spine Cryoablation: Pain Palliation and Local Tumor Control for Vertebral Metastases

BACKGROUND AND PURPOSE

Percutaneous cryoablation has emerged as a minimally invasive technique for the management of osseous metastases. The purpose of this study was to assess the safety and effectiveness of percutaneous imaging-guided spine cryoablation for pain palliation and local tumor control for vertebral metastases.

MATERIALS AND METHODS

Imaging-guided spine cryoablation was performed in 14 patients (31 tumors) with vertebral metastases refractory to conventional chemoradiation therapy or analgesics, to achieve pain palliation and local tumor control in this retrospective study. Spinal nerve and soft-tissue thermal protection techniques were implemented in all ablations. Patient response was evaluated by a pain numeric rating scale administered before the procedure and 1 week, 1 month, and 3 months after the procedure. Pre- and postprocedural analgesic requirements (expressed as morphine-equivalent dosages) were also analyzed at the same time points. Pre- and postprocedural cross-sectional imaging was evaluated in all patients to assess local control (no radiographic evidence of disease at the treated sites). Complications were monitored. Analysis of the primary end points was undertaken via paired-comparison procedures by using the Wilcoxon signed rank test.

RESULTS

Thirty-one tumors were ablated in 14 patients (9 women and 5 men; 20-73 years of age; mean age, 53 years). The most common tumor location was in the lumbar spine (n = 14, 45%), followed by the thoracic spine (n = 8, 26%), sacrum (n = 6, 19%), coccyx (n = 2, 6%), and cervical spine (n = 1, 3%). There were statistically significant decreases in the median numeric rating scale score and analgesic usage at 1-week, 1-month, and 3-month time points (P < .001 for all). Local tumor control was achieved in 96.7% (30/31) of tumors (median follow-up, 10 months). Two patients had transient postprocedural unilateral lower extremity radiculopathy and weakness.

CONCLUSIONS

Percutaneous imaging-guided spine cryoablation is a safe and effective treatment for pain palliation and local tumor control for vertebral metastases.

A Vivens Ex Vivo Study on the Synergistic Effect of Electrolysis and Freezing on the Cell Nucleus

Freezing-cryosurgery, and electrolysis-electrochemical therapy (EChT), are two important minimally invasive surgery tissue ablation technologies. Despite major advantages they also have some disadvantages. Cryosurgery cannot induce cell death at high subzero freezing temperatures and requires multiple freeze thaw cycles, while EChT requires high concentrations of electrolytic products-which makes it a lengthy procedure. Based on the observation that freezing increases the concentration of solutes (including products of electrolysis) in the frozen region and permeabilizes the cell membrane to these products, this study examines the hypothesis that there could be a synergistic effect between freezing and electrolysis in their use together for tissue ablation. Using an animal model we refer to as vivens ex vivo, which may be of value in reducing the use of animals for experiments, combined with a Hematoxylin stain of the nucleus, we show that there are clinically relevant protocols in which the cell nucleus appears intact when electrolysis and freezing are used separately but is affected by certain combinations of electrolysis and freezing.

Cryosurgery/cryoablation in musculoskeletal neoplasms: history and state of the art

The field of cryosurgery began nearly 40 years ago with the open application of liquid nitrogen to ablate tumors. Recent developments in imaging and cryoprobe technology allow for percutaneous ablation of tumors. Computed tomography (CT)-guided cryoablation has particular use in treating musculoskeletal neoplasms because of the ability to image the lethal ice zone around both bone and soft tissue structures. This manuscript will review the development, indications, and results of cryoablation as applied to musculoskeletal neoplasms. This technique holds promise for the treatment of benign conditions as well as the palliation and durable treatment of musculoskeletal metastases; it is not commonly indicated in the curative treatment of primary malignant bone or soft tissue sarcomas.

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.

Histotripsy methods in mechanical disintegration of tissue: towards clinical applications

In high intensity focused ultrasound (HIFU) therapy, an ultrasound beam is focused within the body to locally affect the targeted site without damaging intervening tissues. The most common HIFU regime is thermal ablation. Recently there has been increasing interest in generating purely mechanical lesions in tissue (histotripsy). This paper provides an overview of several studies on the development of histotripsy methods toward clinical applications. Two histotripsy approaches and examples of their applications are presented. In one approach, sequences of high-amplitude, short (microsecond-long), focused ultrasound pulses periodically produce dense, energetic bubble clouds that mechanically disintegrate tissue. In an alternative approach, longer (millisecond-long) pulses with shock fronts generate boiling bubbles and the interaction of shock fronts with the resulting vapour cavity causes tissue disintegration. Recent preclinical studies on histotripsy are reviewed for treating benign prostatic hyperplasia (BPH), liver and kidney tumours, kidney stone fragmentation, enhancing anti-tumour immune response, and tissue decellularisation for regenerative medicine applications. Potential clinical advantages of the histotripsy methods are discussed. Histotripsy methods can be used to mechanically ablate a wide variety of tissues, whilst selectivity sparing structures such as large vessels. Both ultrasound and MR imaging can be used for targeting and monitoring the treatment in real time. Although the two approaches utilise different mechanisms for tissue disintegration, both have many of the same advantages and offer a promising alternative method of non-invasive surgery.

Image-guided cryoablation for the treatment of painful musculoskeletal metastatic disease: a single-center experience

PURPOSE

The role of image-guided thermal ablation techniques for the nonoperative local management of painful osseous metastatic disease has expanded during recent years, and several advantages of cryoablation in this setting have emerged. The purpose of this study is to retrospectively evaluate and report a single-center experience of CT-guided percutaneous cryoablation in the setting of painful musculoskeletal metastatic disease.

METHODS

This study was approved by the institutional review board and is compliant with the Health Insurance Portability and Accountability Act. Electronic medical records of all patients who underwent percutaneous image-guided palliative cryoablation at our institution were reviewed (n = 61). An intent-to-treat analysis was performed. Records were reviewed for demographic data and anatomical data, primary tumor type, procedure details, and outcome-including change in analgesic requirements (expressed as morphine equivalent dosages), pain scores (utilizing the clinically implemented visual analog scale), subsequent therapies (including radiation and/or surgery), and complications during the 24 h following the procedure and at 3 months. Patients were excluded (n = 7) if data were not retrospectively identifiable at the defined time points.

RESULTS

Fifty-four tumors were ablated in 50 patients. There were statistically significant decreases in the median VAS score and narcotic usage at both 24 h and 3 months (p < 0.000). Six patients (11%) incurred complications related to their therapy. Two patients had no relief at 24 h, of which both reported worsened pain at 3 months. One patient had initial relief but symptom recurrence at 3 months. Four patients went on to have radiation therapy of the ablation site at some point following the procedure.

CONCLUSIONS

CT-guided cryoablation is a safe, effective, reproducible procedural option for the nonoperative local treatment of painful musculoskeletal metastatic disease.

Cryoablation of early-stage primary lung cancer

Worldwide, lung cancer is the most commonly diagnosed cancer, and lobectomy is the gold-standard treatment for early-stage non-small cell lung cancer (NSCLC). However, many patients are poor surgical candidates for various reasons. Recently, image-guided ablation is being used for lung tumors. Cryoablation has been applied for the treatment of cancer in various nonaerated organs; recently it has been adapted to the treatment of lung tumors. Since an ice ball can be detected by computed tomography (CT), cryoablation of lung tumors is performed under CT guidance. Its first clinical application was reported in 2005, and it has been reported to be feasible in a few studies. Minor complications occurred at a high frequency (up to 70.5%), but major complications were rare (up to 1%). The most common complication is pneumothorax, and most cases need no further intervention. Local efficacy depends on tumor size and presence of a thick vessel close to the tumor. Midterm survival after cryoablation is 77%–88% at 3 years in patients with early-stage NSCLC. Although surgery is the gold-standard treatment for such patients, the initial results of cryoablation are promising. In this paper, the current status of cryoablation for primary lung tumors is reviewed.

An improved model for nucleation-limited ice formation in living cells during freezing

Ice formation in living cells is a lethal event during freezing and its characterization is important to the development of optimal protocols for not only cryopreservation but also cryotherapy applications. Although the model for probability of ice formation (PIF) in cells developed by Toner et al. has been widely used to predict nucleation-limited intracellular ice formation (IIF), our data of freezing Hela cells suggest that this model could give misleading prediction of PIF when the maximum PIF in cells during freezing is less than 1 (PIF ranges from 0 to 1). We introduce a new model to overcome this problem by incorporating a critical cell volume to modify the Toner's original model. We further reveal that this critical cell volume is dependent on the mechanisms of ice nucleation in cells during freezing, i.e., surface-catalyzed nucleation (SCN) and volume-catalyzed nucleation (VCN). Taken together, the improved PIF model may be valuable for better understanding of the mechanisms of ice nucleation in cells during freezing and more accurate prediction of PIF for cryopreservation and cryotherapy applications.

Cryotherapy for primary treatment of prostate cancer: intermediate term results of a prospective study from a single institution

Purpose. Published data about cryotherapy for prostate cancer (PC) treatment are based on case series with a lack of clinical trials and the inexistence of a validated definition of biochemical failure. A prospective study with standardized followup protocol was conducted in our institution. Material and Methods. Prospective study of a series of cases including 108 patients diagnosed with localized PC at clinical stage T1c-T2c treated by primary cryoablation and median followup of 61 months. Criteria of biochemical recurrence were unified according to the American Society for Therapeutic Radiology and Oncology (ASTRO). End points were biochemical progression-free survival (BPFS), cancer-specific survival, and overall survival. Rate of complications was reported. Results. The BPFS for low-, medium-, and high-risk patients was 96.4%, 91.2%, and 62.2%, respectively. Cancer-specific survival was 98.1%. Overall survival reached 94.4%. Complications included incontinence in 5.6%, urinary tract obstruction in 1.9%, urethral sloughing in 5.6%, haematuria in 1.9%, perineal pain in 11.1%, and prostatorectal fistula in 0.9%. Erectile disfunction was found in 98.1%. Conclusions. Cryotherapy is an effective and minimally invasive treatment for primary PC in well-selected cases, with low surgical risk and good results in terms of BPFS, cancer-specific survival, and overall survival.

Mechanisms of cryoablation: clinical consequences on malignant tumors

While the destructive actions of a cryoablative freeze cycle are long recognized, more recent evidence has revealed a complex set of molecular responses that provides a path for optimization. The importance of optimization relates to the observation that the cryosurgical treatment of tumors yields success only equivalent to alternative therapies. This is also true of all existing therapies of cancer, which while applied with curative intent; provide only disease suppression for periods ranging from months to years. Recent research has led to an important new understanding of the nature of cancer, which has implications for primary therapies, including cryosurgical treatment. We now recognize that a cancer is a highly organized tissue dependent on other supporting cells for its establishment, growth and invasion. Further, cancer stem cells are now recognized as an origin of disease and prove resistant to many treatment modalities. Growth is dependent on endothelial cells essential to blood vessel formation, fibroblasts production of growth factors, and protective functions of cells of the immune system. This review discusses the biology of cancer, which has profound implications for the diverse therapies of the disease, including cryosurgery. We also describe the cryosurgical treatment of diverse cancers, citing results, types of adjunctive therapy intended to improve clinical outcomes, and comment briefly on other energy-based ablative therapies. With an expanded view of tumor complexity we identify those elements key to effective cryoablation and strategies designed to optimize cancer cell mortality with a consideration of the now recognized hallmarks of cancer.

Changes in the expression of serum markers CA242, CA199, CA125, CEA, TNF-α and TSGF after cryosurgery in pancreatic cancer patients

The presence of serum tumor markers, carbohydrate antigen 242 (CA242), carbohydrate antigen 199 (CA199), carbohydrate antigen 125 (CA125), carcinoembryonic antigen (CEA), tumor-supplied group of factors (TSGF) and tumor necrosis factor-α (TNF-α), is closely associated with invasion and metastasis of many malignancies. The expression of these markers were measured in serum taken from 37 pancreatic cancer patients prior to treatment. Levels of CA242, CA199, CA125, CEA and TNF-α expression correlated with tumor size, clinical stage, tumor differentiation, lymph node and liver metastasis (P < 0.05). One month after cryosurgery, serum levels of these markers were significantly reduced compared with levels prior to cryosurgery (P < 0.05), whereas there was no significant difference was found between serum levels before and after chemotherapy (P > 0.05). Thus, cryosurgery is more effective than chemotherapy for decreasing CA242, CA199, CA125, CEA, TSGF and TNF-α serum levels in these patients.

Microwave ablation of the liver: a description of lesion evolution over time and an investigation of the heat sink effect

AIM

Microwave ablation has been successfully used to treat unresectable liver tumours for many years. However, despite its widespread use, there seems to be a relative paucity of experimental data regarding lesion evolution and the effects of any surrounding vasculature on ablation morphology. The aim of this study was to investigate the principal pathological changes in the liver following microwave ablation, in particular the heat sink effect. In addition we carefully reviewed the available literature to provide an overview of all relevant pathological studies.

METHODS

Microwave ablation was carried out on male rats at various distances from the hilum. Histological (H&E) and immunocytochemical (caspase 3) analyses of the lesion were performed at various time points; 0, 4, 24, 48  hours, 2 weeks and 1 month. A literature review was carried out using Medline, Embase and the Cochrane database to identify all relevant histological studies.

RESULTS

The lesion underwent complete coagulative necrosis and was extremely regular at the ablation edge with no evidence of any influence from surrounding blood vessels at all time points. H&E and caspase 3 results were consistent and microwave caused little collateral damage outside the intended ablation zone.

CONCLUSION

This study suggests that microwave ablation is extremely concise and is minimally affected by the heat sink effect. Comparative investigations with other treatment modalities are required.

Nanoparticle preconditioning for enhanced thermal therapies in cancer

Nanoparticles show tremendous promise in the safe and effective delivery of molecular adjuvants to enhance local cancer therapy. One important form of local cancer treatment that suffers from local recurrence and distant metastases is thermal therapy. In this article, we review a new concept involving the use of nanoparticle-delivered adjuvants to 'precondition' or alter the vascular and immunological biology of the tumor to enhance its susceptibility to thermal therapy. To this end, a number of opportunities to combine nanoparticles with vascular and immunologically active agents are reviewed. One specific example of preconditioning involves a gold nanoparticle tagged with a vascular targeting agent (i.e., TNF-α). This nanoparticle embodiment demonstrates preconditioning through a dramatic reduction in tumor blood flow and induction of vascular damage, which recruits a strong and sustained inflammatory infiltrate in the tumor. The ability of this nanoparticle preconditioning to enhance subsequent heat or cold thermal therapy in a variety of tumor models is reviewed. Finally, the potential for future clinical imaging to judge the extent of preconditioning and thus the optimal timing and extent of combinatorial thermal therapy is discussed.

Percutaneous bone tumor management

Interventional radiology plays a major role in the management of bone tumors. Many different percutaneous techniques are available. Some aim to treat pain and consolidate a pathological bone (cementoplasty); others aim to ablate tumor or reduce its volume (sclerotherapy, thermal ablation). In this article, image-guided techniques of primary and secondary bone tumors with vertebroplasty, ethanol injection, radiofrequency ablation, laser photocoagulation, cryoablation, and radiofrequency ionization (coblation) will be reviewed. For each modality, the principles, the indications, and the results will be presented. The technical choice depends on the therapeutic intent-curative or palliative-and the need for consolidation, but also on the general status of the patient and the other therapeutic options. For the most complex cases, combined treatments can be required. However, the less disabling technique should always be considered first.

Thermostability of biological systems: fundamentals, challenges, and quantification

This review examines the fundamentals and challenges in engineering/understanding the thermostability of biological systems over a wide temperature range (from the cryogenic to hyperthermic regimen). Applications of the bio-thermostability engineering to either destroy unwanted or stabilize useful biologicals for the treatment of diseases in modern medicine are first introduced. Studies on the biological responses to cryogenic and hyperthermic temperatures for the various applications are reviewed to understand the mechanism of thermal (both cryo and hyperthermic) injury and its quantification at the molecular, cellular and tissue/organ levels. Methods for quantifying the thermophysical processes of the various applications are then summarized accounting for the effect of blood perfusion, metabolism, water transport across cell plasma membrane, and phase transition (both equilibrium and non-equilibrium such as ice formation and glass transition) of water. The review concludes with a summary of the status quo and future perspectives in engineering the thermostability of biological systems.