Effect of thermal variables on human breast cancer in cryosurgery

Breast Cancer Cryoablation Fundamentals Past and Present: Technique Optimization and Imaging Pearls

Surgical treatment for breast cancer has evolved from radical mastectomy to modified radical mastectomy to breast-conserving surgery. As the de-escalation of surgical treatment for breast cancer continues, nonsurgical treatment for early-stage breast cancer with favorable ancillary features (low grade, positivity for hormone receptors) is being explored. Of the nonsurgical treatment options, cryoablation has demonstrated the greatest appeal, proven to be effective, safe, well tolerated, and feasible in an outpatient setting with local anesthetic alone. Results of past and interim results of current trials of cryoablation of stage I low-grade breast cancer with curative intent are promising, with an overall clinical success rate of 98% and recurrence rates consistent with those expected following lumpectomy. Cryoablation is also an alternative palliative treatment for patients who cannot tolerate or who have disease that is refractory to or recurs after standard-of-care breast cancer treatment and may have immunological therapeutic effects, warranting future research. Understanding the indications and optimal technique for breast cancer cryoablation and understanding typical imaging findings after cryoablation are essential to ensure the success of the procedure in carefully selected patients.

A Breast-Specific MR Guided Focused Ultrasound Platform and Treatment Protocol: First-in-Human Technical Evaluation

OBJECTIVE

This paper presents and evaluates a breast-specific magnetic resonance guided focused ultrasound (MRgFUS) system. A first-in-human evaluation demonstrates the novel hardware, a sophisticated tumor targeting algorithm and a volumetric magnetic resonance imaging (MRI) protocol.

METHODS

At the time of submission, N = 10 patients with non-palpable T0 stage breast cancer have been treated with the breast MRgFUS system. The described tumor targeting algorithm is evaluated both with a phantom test and in vivo during the breast MRgFUS treatments. Treatments were planned and monitored using volumetric MR-acoustic radiation force imaging (MR-ARFI) and temperature imaging (MRTI).

RESULTS

Successful technical treatments were achieved in 80 % of the patients. All patients underwent the treatment with no sedation and 60 % of participants had analgesic support. The total MR treatment time ranged from 73 to 114 minutes. Mean error between desired and achieved targeting in a phantom was 2.9 ±1.8 mm while 6.2 ±1.9 mm was achieved in patient studies, assessed either with MRTI or MR-ARFI measurements. MRTI and MR-ARFI were successful in 60 % and 70 % of patients, respectively.

CONCLUSION

The targeting accuracy allows the accurate placement of the focal spot using electronic steering capabilities of the transducer. The use of both volumetric MRTI and MR-ARFI provides complementary treatment planning and monitoring information during the treatment, allowing the treatment of all breast anatomies, including homogeneously fatty breasts.

Cryoablation In The Management Of Breast Cancer: Evidence To Date

Cryoablation has been successfully used to treat various type of solid tumors, including breast carcinomas. This ablation method has the advantage of being a minimally invasive procedure useful in various clinical situations, including early breast cancer and metastatic breast cancer, when co-morbidities preclude the use of surgical treatment. However, due to the small sample size of the available studies, reliable and definitive conclusions on the usefulness of cryoablation in patients with breast cancer could not be drawn. In fact, many aspects necessitate to be elucidated, regarding technical issues, indications, efficacy, imaging follow-up, and possible advantages over other percutaneous ablative methods. This review article has the aim to clarify the current evidence supporting cryoablation of breast cancer, and discuss the future perspectives, including those arising from the new studies on immunological effects related to cryoablation.

Role of interventional radiology in managing pediatric liver tumors : Part 2: percutaneous interventions

Hepatoblastoma and hepatocellular carcinoma (HCC) are the most common pediatric liver malignancies, with hepatoblastoma occurring more commonly in younger children and HCC occurring more commonly in older children and adolescents. Although surgical resection (including transplant when necessary) and systemic chemotherapy have improved overall survival rate for hepatoblastoma to approximately 80% from 30%, a number of children with this tumor type are not eligible for operative treatment. In contradistinction, pediatric HCC continues to carry a dismal prognosis with an overall 5-year survival rate of 30%. The Paediatric Hepatic International Tumour Trial (PHITT) is an international trial aimed at evaluating both existing and emerging oncologic therapies for primary pediatric liver tumors. Interventional radiology offers a number of minimally invasive procedures that aid in diagnosis and therapy of pediatric liver tumors. For diagnosis, the PHITT biopsy guidelines emphasize and recommend percutaneous image-guided tumor biopsy. Additionally, both percutaneous and endovascular procedures provide therapeutic alternatives that have been, to this point, only minimally utilized in the pediatric population. Specifically, percutaneous ablation offers a number of cytotoxic technologies that can potentially eradicate disease or downstage children with unresectable disease. Percutaneous portal vein embolization is an additional minimally invasive procedure that might be useful to induce remnant liver hypertrophy prior to extended liver resection in the setting of a primary liver tumor. PHITT offers an opportunity to collect data from children treated with these emerging therapeutic options across the world. The purpose of this manuscript is to describe the potential role of minimally invasive percutaneous transhepatic procedures, as well as review the existing data largely stemming from the adult HCC experience.

Decision Making: Thermal Ablation Options for Small Renal Masses

Renal cell carcinoma is a relatively common tumor, with an estimated 63,000 new cases being diagnosed in the United States in 2016. Surgery, be it with partial or total nephrectomy, is considered the mainstay of treatment for many patients. However, those patients with small renal masses, typically less than 3 to 4 cm in size who are deemed unsuitable for surgery, may be suitable for percutaneous thermal ablation. We review the various treatment modalities, including radiofrequency ablation, microwave ablation, and cryoablation; discuss the advantages and disadvantages of each method; and review the latest data concerning the performance of the various ablative modalities compared with each other, and compared with surgery.

An Electrochemistry Study of Cryoelectrolysis in Frozen Physiological Saline

Cryoelectrolysis is a new minimally invasive tissue ablation surgical technique that combines the processes of electrolysis and solid/liquid phase transformation (freezing). This study investigated this new technique by measuring the pH front propagation and the changes in resistance in a tissue simulant made of physiological saline gel with a pH dye as a function of the sample temperature in the high subzero range above the eutectic. Results demonstrated that effective electrolysis can occur in a high subzero freezing milieu and that the propagation of the pH front is only weakly dependent on temperature. These observations are consistent with a mechanism involving ionic movement through the concentrated saline solution channels between ice crystals at subfreezing temperatures above the eutectic. Moreover, results suggest that Joule heating in these microchannels may cause local microscopic melting, the observed weak dependence of pH front propagation on temperature, and the large changes in resistance with time. A final insight provided by the results is that the pH front propagation from the anode is more rapid than from the cathode, a feature indicative of the electro-osmotic flow from the cathode to the anode. The findings in this paper may be critical for designing future cryoelectrolytic ablation surgery protocols.

Cryosurgery for Tumors — A Clinical Overview

Cryosurgery, a method of treating disease by the production of freezing temperatures in the tissue, is a useful technique for the treatment of tumors. When the modern era of cryosurgery began in the mid 1960's, the technique was used only for tumors easily accessible by direct observation or via endoscopy, such as those of the skin, oral cavity, and prostate gland. In general, the technique had limited usefulness in the next two decades. However, with the advent of intraoperative ultrasound as a method of monitoring the process of freezing and with the development of more effective cryosurgical apparatus, the cryosurgical treatment of tumors of the viscera and other deep tissues became practical in the 1990's. This review assesses the present day status of cryosurgery in the management of diverse tumors.

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 tools: microwave, radiofrequency, or cryoablation--what should you use and why?

Image-guided thermal ablation is an evolving and growing treatment option for patients with malignant disease of multiple organ systems. Treatment indications have been expanding to include benign tumors as well. Specifically, the most prevalent indications to date have been in the liver (primary and metastatic disease, as well as benign tumors such as hemangiomas and adenomas), kidney (primarily renal cell carcinoma, but also benign tumors such as angiomyolipomas and oncocytomas), lung (primary and metastatic disease), and soft tissue and/or bone (primarily metastatic disease and osteoid osteomas). Each organ system has different underlying tissue characteristics, which can have profound effects on the resulting thermal changes and ablation zone. Understanding these issues is important for optimizing clinical results. In addition, thermal ablation technology has evolved rapidly during the past several decades, with substantial technical and procedural improvements that can help improve clinical outcomes and safety profiles. Staying up to date on these developments is challenging but critical because the physical properties underlying the different ablation modalities and the appropriate use of adjuncts will have a tremendous effect on treatment results. Ultimately, combining an understanding of the physical properties of the ablation modalities with an understanding of the thermal kinetics in tissue and using the most appropriate ablation modality for each patient are key to optimizing clinical outcomes. Suggested algorithms are described that will help physicians choose among the various ablation modalities for individual patients.

Percutaneous tumor ablation tools: microwave, radiofrequency, or cryoablation--what should you use and why?

Image-guided thermal ablation is an evolving and growing treatment option for patients with malignant disease of multiple organ systems. Treatment indications have been expanding to include benign tumors as well. Specifically, the most prevalent indications to date have been in the liver (primary and metastatic disease, as well as benign tumors such as hemangiomas and adenomas), kidney (primarily renal cell carcinoma, but also benign tumors such as angiomyolipomas and oncocytomas), lung (primary and metastatic disease), and soft tissue and/or bone (primarily metastatic disease and osteoid osteomas). Each organ system has different underlying tissue characteristics, which can have profound effects on the resulting thermal changes and ablation zone. Understanding these issues is important for optimizing clinical results. In addition, thermal ablation technology has evolved rapidly during the past several decades, with substantial technical and procedural improvements that can help improve clinical outcomes and safety profiles. Staying up to date on these developments is challenging but critical because the physical properties underlying the different ablation modalities and the appropriate use of adjuncts will have a tremendous effect on treatment results. Ultimately, combining an understanding of the physical properties of the ablation modalities with an understanding of the thermal kinetics in tissue and using the most appropriate ablation modality for each patient are key to optimizing clinical outcomes. Suggested algorithms are described that will help physicians choose among the various ablation modalities for individual patients.

Bronchoscopic debulking for endobronchial malignancy: Predictors of recanalization and recurrence

Background

Central airway obstruction related to endobronchial malignancy is one of the most difficult oncological complications and requires efficient palliative intervention.

Methods

Fifty-three consecutive patients with unresectable endobronchial malignancy receiving bronchoscopic cryotherapy as palliative treatment were retrospectively reviewed. Efficiency was evaluated by the improvement of performance status (PS), and the best achievement of tumor removal was assessed as complete or partial removal.

Result

Patients’ PS after cryotherapeutic tumor removal improved from the baseline PS (P = 0.006). In multivariate logistic regression analysis, the compression part of the tumor (odds ratio [OR] 0.42; 95% confidence interval [CI] 0.23∼0.75, P = 0.004) and the thin tumor stalk (OR 87.86; 95% CI 2.31∼3337.37, P = 0.016) were independent predictors of complete tumor removal. Tumors larger than 9.3 cm, including compression and invasion parts, had the highest odds of being only partially removed (positive predictive value [PPV]: 88.2%, likelihood ratio [LR]+: 10.49); tumors smaller than 9.3 cm were likely to be completely removed (negative predictive value [NPV]: 80.6%, LR−: 0.34). After cryotherapy, re-obstruction was significantly associated with non-squamous cell carcinoma (65.7 vs. 16.7%, P = 0.001) and patients who had longer overall survival (11.7 vs. 1.5 months, P < 0.001). Odds of tumor re-obstruction increased 2.28-fold (PPV: 81.6%, LR+: 2.28) beyond two months; the odds decreased by 81% (NPV: 73.3%, LR−: 0.19) within two months.

Conclusion

Debulking of a tumor using cryotherapy is a useful palliative treatment for endobronchial obstruction secondary to a variety of malignancies.

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.

Current status of imaging-guided percutaneous ablation of breast cancer

OBJECTIVE

The purpose of this article is to briefly describe the various techniques used for percutaneous ablation of breast cancer, their preliminary results, and their limitations. The techniques include thermotherapy (radiofrequency ablation, laser irradiation, microwave irradiation, and insonation with high-intensity focused ultrasound waves), cryotherapy, and irreversible electroporation.

CONCLUSION

The techniques used for percutaneous ablation of breast cancer raise many questions and issues that must be addressed before percutaneous ablation can be adopted for the treatment of early breast cancer.

Nonsurgical ablation of breast cancer: future options for small breast tumors

The surgical management of breast cancer has evolved significantly, facilitated by advancements in technology and imaging and improvements in adjuvant therapy. The changes in surgical management have been characterized by equal or improved outcomes with significantly less morbidity. The next step in this evolution is the minimally invasive or noninvasive ablation of breast cancers as an alternative to lumpectomy. In this article, the various modalities for nonsurgical breast cancer ablation and the clinical experience are reviewed, and some of the next steps necessary for their clinical implementation are outlined.

Volumetric MRI-guided high-intensity focused ultrasound for noninvasive, in vivo determination of tissue thermal conductivity: initial experience in a pig model

PURPOSE

To estimate the local thermal conductivity of porcine thigh muscle at temperatures required for magnetic resonance imaging (MRI)-guided high-intensity focused ultrasound (MRgHIFU) surgery (60-90°C).

MATERIALS AND METHODS

Using MRgHIFU, we performed 40 volumetric ablations in the thigh muscles of four pigs. Thirty-five of the sonications were successful. We used MRI to monitor the resulting temperature increase. We then determined local thermal conductivity by analyzing the spatiotemporal spread of temperature during the cooling period.

RESULTS

The thermal conductivity of MRgHIFU-treated porcine thigh muscle fell within a narrow range (0.52 ± 0.05 W/[m*K]), which is within the range reported for porcine thigh muscle at temperatures of <40°C (0.52 to 0.62 W/[m*K]). Thus, there was little change in the thermal conductivity of porcine thigh muscle at temperatures required for MRgHIFU surgery compared to lower temperatures.

CONCLUSION

Our MRgHIFU-based approach allowed us to estimate, with good reproducibility, the local thermal conductivity of in vivo deep tissue in real time at temperatures of 60°C to 90°C. Therefore, our method provides a valuable tool for quantifying the influence of thermal conductivity on temperature distribution in tissues and for optimizing thermal dose delivery during thermal ablation with clinical MRgHIFU.

Ablative therapies of the breast

Minimally invasive ablative therapy techniques are being used in research protocols to treat benign and malignant tumors of the breast in select patient populations. These techniques offer the advantages of an outpatient setting, decreased pain, and improved cosmesis. These therapies, including radiofrequency ablation, cryotherapy, interstitial laser therapy, high-intensity focused ultrasonography, and focused microwave thermotherapy, are reviewed in this article.

Cryoinsult parameter effects on the histologically apparent volume of experimentally induced osteonecrotic lesions

Investigation of femoral head osteonecrosis would benefit from an animal model whose natural history includes progression to bony collapse of a segmental necrotic lesion. The bipedal emu holds attraction for systematic organ-level study of collapse mechanopathology. One established method of experimentally inducing segmental lesions is liquid nitrogen cryoinsult. Four cryoinsult parameters-hold temperature, freeze duration, freeze/thaw repetition, and thaw duration-were investigated to determine their individual and combined effects on resulting necrotic lesion morphology. 3D distributions of histologically apparent osteocyte necrosis from 24 emus receiving varying cryoinsults were used to develop univariate and multivariate linear regression models relating resulting necrotic lesion morphology to particular cryoinsult input parameters. These models were then applied to predict lesion size in four additional emus receiving differing input cryoinsults. The best multivariate regression model predicted lesion volumes that were accurate to better than 8% of overall emu femoral head volume. The hold temperature during cryoinsult was by far the most influential cryoinsult input parameter. The utility of this information is to enhance the consistency and predictability of cryoinsult-induced segmental lesion size for the purposes of systematic laboratory studies at the whole-organ level.

Cryotherapy for breast cancer: a feasibility study without excision

PURPOSE

To assess the feasibility of percutaneous multiprobe breast cryoablation (BC) for diverse presentations of cancers that remained in situ after BC.

MATERIALS AND METHODS

After breast magnetic resonance (MR) imaging and thorough consultation, patients underwent BC after giving informed consent. This study was approved by the institutional review board. In 12 BC sessions, 22 breast cancer foci (stages I-IV) were treated in 11 patients who refused surgery by using multiple 2.4-mm cryoprobes. Five patients had recurrent disease and six had new diagnoses. With use of only local anesthesia, six patients were treated with ultrasonographic (US) guidance and five were treated with both computed tomographic (CT) and US guidance. Saline injections and warming bags were used to protect the skin. Procedure success was defined as 1 cm visible ice beyond all tumor margins. MR imaging and/or clinical follow-up were available for up to 72 months after BC.

RESULTS

US produced sufficient ice visualization for small tumors, whereas CT helped confirm overall ice extent. The mean pretreatment breast tumor diameter was 1.7 cm +/- 1.2 (range, 0.5-5.8 cm), and an average of 3.1 cryoprobes produced 100% procedural success with mean ice diameters of 5.1 cm +/- 2.2 (range, 2.0-10.0 cm). No significant complications, retraction, or scarring were noted. Biopsies at the margins of the cryoablation site immediately after BC and at follow-up were all negative. No local recurrences have been noted at an average imaging follow-up of 18 months.

CONCLUSIONS

In conjunction with thorough pre- and postablation MR imaging, CT/US-guided multiprobe BC safely achieved 1 cm visible ice beyond tumor margins with minimal discomfort, good cosmesis, and no short-term local tumor recurrences.

Study on tumor microvasculature damage induced by alternate cooling and heating

Tumor vasculature damage induced by various thermal treatments has been studied in vivo via laser confocal microscopy. Murine mammary carcinoma 4T1 was implanted in the nude mice dorsal skin fold window chamber. The implanted tumor was treated by alternate cooling and heating. Results showed that the treatment was much more effective as compared with that of cooling or heating alone, especially in damaging the tumor vasculature. In general, tumor vascular response to thermal stimuli was heterogeneous. All the treatments of hyperthermia at 42 degrees C (for 1 h), alternate cooling at 1 degrees C and heating at 42 degrees C (for 1/2 h each) and that of -10 degrees C/42 degrees C (for 1/2 h each) enhanced liposome extravasation. Pre-cooling tumor at 1 degrees C preserved most of the vascular integrity but partially inhibited the effect of post-hyperthermia at 42 degrees C. On the other hand, cooling at -10 degrees C for 1/2 h before heating at 42 degrees C caused severe vessel damage. Histo-pathological analyses further confirmed the effect as rare tumor vessel recurrence and large necrotic tumor tissue areas shown on the 7th day after the treatment.

An analytical study on the thermal effects of cryosurgery on selective cell destruction

The aim of cryosurgery is to kill cells within a closely defined region maintained at a predetermined low temperature. To effectively kill cells, it is important to be able to predict and control the cooling rate over some critical range of temperatures and freezing states in order to regulate the spatial extent of injury during any freeze-thaw protocol. The objective of manipulating the freezing parameters is to maximize the destruction of cancer cells within a defined spatial domain while minimizing cryoinjury to the surrounding healthy tissue. An analytical model has been developed to study the rate of cell destruction within a liver tumor undergoing a freeze-thaw cryosurgical process. Temperature transients in the tumor undergoing cryosurgery have been quantitatively investigated. The simulation is based on solving the transient bioheat equation using the finite volume scheme for a single or multiple-probe geometry. Simulated results show good agreement with experimental data obtained from in vivo clinical study. The calibrated model has been employed to study the effects of different freezing rates, freeze-thaw cycle(s), and multi-probe freezing on cell damage in a liver tumor. The effectiveness of each treatment protocol is estimated by generating the cell survival-volume signature and comparing the percentage of cell damaged within the ice-ball. Results from the model show that employing freeze-thaw cycles has the potential to enhance cell destruction within the cancerous tissue. Results from this study provide the basis for designing an optimized cryosurgical protocol which incorporates thermal effects and the extent of cell destruction within tumors.

Adoptive immunotherapy of breast cancer with lymph node cells primed by cryoablation of the primary tumor

Cryoablation of cancer leaves tumor-associated antigens intact in an inflammatory microenvironment that can stimulate a regional anti-tumor immune response. We examined whether cryoablated tumor draining lymph nodes (CTDLN) as adoptive immunotherapy may be an effective immunotherapeutic approach in the adjuvant treatment of breast cancer. BALB/c mice with MT-901 mammary adenocarcinoma tumors underwent cryoablation, resection or no treatment and tumor draining lymph nodes were harvested. Cryoablation resulted in only a mild increase in the absolute number of T-cells but a significant increase in the fraction of tumor-specific T-cells as evidenced on IFN-gamma release assay. FACS analysis demonstrated no significant relative shift in the proportion of CD4(+) or CD8(+) cells. The adoptive transfer of CTDLN resulted in a significant reduction of pulmonary metastases as compared to TDLN from either tumor-bearing mice or mice who underwent surgical excision. Cryoablation prior to surgical resection of breast cancer can be used as a method to generate effector T-cells for adjuvant adoptive cellular immunotherapy.

Magnetic Resonance–Guided Focused Ultrasound Surgery of Breast Cancer: Reliability and Effectiveness

BACKGROUND

Magnetic resonance-guided focused ultrasound surgery (MRgFUS) is a noninvasive technique that has been shown to coagulate benign and malignant tumors. The purpose of this study was to evaluate MRgFUS safety and effectiveness for the ablation of breast carcinomas.

STUDY DESIGN

Thirty women with biopsy-proved breast cancer underwent MRgFUS treatment. Gadolinium-enhanced MR images were used for treatment planning and posttreatment radiologic assessment of treated tissue, and temperature-sensitive MR images provided real-time treatment monitoring. After MRgFUS, all 30 women underwent wide excision or mastectomy. The extent of thermal ablation was assessed with tumor histology.

RESULTS

Treatment was well tolerated, with a minimum of adverse effects, especially when performed under local anesthesia. On pathologic examination, mean (+/-SD) necrosis of the targeted breast tumors was 96.9 +/- 4% (median 100%, range 78% to 100%) of tumor volume. Fifteen (53.5%) of 28 evaluable patients had 100% necrosis of the ablated tumor; only 3 patients (10.7%) had less than 95% necrosis. In 28 (93.3%) patients, 100% of the malignancy was within the treatment field, and 98% and 95% of tumor lay within the treatment field in 2 remaining patients. Retrospective analysis in two patients with residual tumor showed treatment was not delivered to the full recommended area, reaffirming the need for precise localization and the value of contrast-enhanced images for treatment planning.

CONCLUSIONS

MRgFUS has great potential to become a viable noninvasive replacement for lumpectomy. Additional studies focusing on posttreatment image-based evaluation are needed.

Office-Based Cryoablation of Breast Fibroadenomas with Long-Term Follow-up

Approximately 10% of women will experience a breast fibroadenoma in their lifetime. Cryoablation is a new treatment that combines the better attributes of the current standards: surveillance and surgery. It is a minimally invasive office-based procedure that is administered without the use of general anesthesia, involving minimal patient discomfort and little to no scarring. This work aimed to establish the long-term (2-3 years) efficacy, safety, and satisfaction of the procedure, as well as the impact of cryoablation on mammogram and ultrasound images. Thirty-seven treated fibroadenomas were available for assessment with an average follow-up period of 2.6 years. Of the original 84% that were palpable prior to treatment, only 16% remained palpable to the patient as of this writing. Of those fibroadenomas that were initially < or = 2.0 cm in size, only 6% remained palpable. A median volume reduction of 99% was observed with ultrasound. Ninety-seven percent of patients and 100% of physicians were satisfied with the long-term treatment results. Mammograms and ultrasounds showed cryoablation produced no artifact that would adversely affect interpretation. Cryoablation for breast fibroadenomas has previously been reported as safe and effective both acutely and at the 1-year follow-up mark, and thus has been implemented as a treatment option. At long-term follow-up, cryoablation as a primary therapy for breast fibroadenomas demonstrates progressive resolution of the treated area, durable safety, and excellent patient and physician satisfaction. The treatment is performed in an office setting rather than an operating room, resulting in a cost-effective and patient-friendly procedure. Cryoablation should be considered a preferred option for those patients desiring definitive therapy for their fibroadenomas without surgical intervention.

Ablative therapies for the treatment of malignant diseases of the breast

BACKGROUND

Because widespread screening for breast cancer is detecting more women at younger ages and earlier stages, the need for minimally invasive, cosmetically preferable approaches to its treatment is growing. Ablative techniques are now being applied to the treatment of primary breast tumors, perhaps offering an alternative to surgical excision. Techniques available for breast cancer treatment include radiofrequency ablation, cryoablation, interstitial laser ablation, microwave thermotherapy, and focused ultrasound ablation.

DATA SOURCES

Literature searches for breast and cryoablation, focused ultrasound ablation, interstitial laser ablation, microwave thermotherapy, and radiofrequency ablation were performed. Over 30 articles were identified and analyzed.

CONCLUSIONS

It is cautiously optimistic that these therapies can be used as a routine adjunct in the treatment of selected breast cancers. The challenge will lie in the ability to identify multifocal disease and in situ carcinoma as well as to ensure complete and effective eradication of the breast cancer.

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.

Small (<2.0-cm) Breast Cancers: Mammographic and US Findings at US-guided Cryoablation—Initial Experience

PURPOSE

To determine the mammographic and ultrasonographic (US) findings at cryoablation of small solitary invasive breast cancers and compare them with presence of residual malignancy after treatment.

MATERIALS AND METHODS

Institutional review board approval and informed patient consent were obtained. Nine patients with small solitary invasive breast cancers diagnosed at core biopsy were treated with US-guided cryoablation and a 2.7-mm cryoprobe. Mean cancer size was 12 mm (range, 8-18 mm); four were palpable. Tabletop argon gas-based cryoablation system with a double-freeze-thaw protocol was used to treat cancers in outpatient setting. Tumor sites were excised at lumpectomy 2-3 weeks after cryoablation. Findings at mammography and US before, during, and after cryoablation were assessed to categorize densities and masses on mammograms and masses on US images with Breast Imaging Reporting and Data System (BI-RADS); maximum cancer size was measured. Imaging findings and clinical breast examination data were compared with histologic findings from lumpectomy specimens to determine presence of intraductal or invasive cancer.

RESULTS

With US guidance, ice balls (maximal mean size, 4.4 cm) were formed around cancers. Before excision, eight patients underwent mammography; all had new focal densities (maximum size, 2.5-5.0 cm) at cancer sites. Six patients underwent preexcisional US; 100% of them had new hyperechogenicity in tissue surrounding cancer site. Seven (78%) of nine patients had no residual cancer; specimens contained fat necrosis. One patient had a small focus of invasive cancer; one had extensive multifocal ductal carcinoma in situ. Patients with BI-RADS category 1 or 2 densities on mammograms or nonpalpable tumors had no residual malignancy. No residual invasive cancer occurred in tumors 17 mm or smaller or in cancers without spiculated margins at US.

CONCLUSION

After cryoablation, there was increased echogenicity at US and increased density at mammography; these findings were observed in areas that approximated location and size of the ice ball. Tumor size, mammographic density, and US characteristics may be indicators of likelihood of complete cryoablation.

Cryotherapy for breast fibroadenomas

PURPOSE

To assess freezing protocols, imaging, and clinical outcomes of percutaneous ultrasonographically (US)-guided cryotherapy for breast fibroadenomas.

MATERIALS AND METHODS

Institutional review board approval and patient consent were obtained. Forty-two biopsy-confirmed fibroadenomas were treated in 29 patients (mean age, 27 years) by using a 2.4-mm cryoprobe inserted into the fibroadenoma with US guidance. The first seven patients underwent conscious sedation, but the other 22 patients required only local anesthesia. US and thermocouple monitoring of the procedure were performed to evaluate freeze protocols based on tumor size. Saline injections protected the skin and/or chest wall. US follow-up was performed at 1 week and at 1, 3, 6, and 12 months. Pre- and 12-month postcryotherapy mammograms were available for seven patients who were over 30 years old. chi(2) and Student t tests were used to assess frequency and mean differences, respectively.

RESULTS

The 22 patients who underwent local anesthesia reported minimal discomfort. No significant complications were noted, and patients were very pleased with the resolution of palpable mass effect and cosmetic results. The average pretreatment fibroadenoma volume of 4.2 cm(3)+/- 4.7 (standard deviation) was reduced to 0.7 cm(3)+/- 0.8 at 12-month follow-up (73% reduction, P < .001). US produced excellent ice visualization beyond tumor margins, while thermocouples confirmed cytotoxic temperatures approximately 5 mm behind the visible leading edge. Two patients elected to undergo either removal or biopsy of a residual mass, which revealed a shrunken hyaline matrix with preserved collagenous architecture. Mammograms showed comparable resolution of mass effects with mild surrounding parenchymal reaction.

CONCLUSION

Cryotherapy of fibroadenomas is a safe, effective, and virtually painless clinic-based (ie, outpatient) treatment option with good cosmesis.

The application of cryosurgery in the treatment of lung cancer

Lung cancer is the commonest cause of cancer death, with a very poor survival rate. By the time of diagnosis, most cases are at an advanced stage and about 30% present with symptoms caused by central endobronchial obstruction. Endobronchial cryosurgery is an effective technique, which can be used to relieve tracheobronchial obstruction caused by lung cancer. This report describes the technique, using a nitrous oxide cooled cryoprobe, inserted through a bronchoscope, to remove the obstruction and reopen the airway. In this study, 476 consecutive patients (mean age 68.3 years, M:F ratio 1.9:1) with obstructive tracheobronchial tumours underwent a mean of 2.4 cryosurgical treatments. Their TNM staging was, stage II 6.7%, IIIa 21.0%, IIIb 23.9%, IV 48.4%. Improvement in symptom quantification was found with 76.4, 69.0, 59.2, and 42.6% of symptomatic patients for haemoptysis, cough, dyspnoea, and chest pain, respectively. Mean values for respiratory function improved from 1.38 to 1.41 litres for FEV1 and 1.91 to 2.04 litres for FVC (p </= 0.0001). Mean performance status improved from 59.6 to 75.2 for Karnofsky scale and 3.04 to 2.20 for the WHO scale and the complication rate was 3.5% of treatments. The Kaplan-Meier median survival was 8.2 months and 1- and 2-year survival 38.4 and 15.9%, respectively. Survival analysis suggested a possible survival advantage over alternative palliative techniques. Endobronchial cryosurgery provides a safe and effective method for the palliation of otherwise inoperable lung cancer. It has advantages over other methods in terms of safety, cost, and a low complication rate. Cryosurgery can be repeated as often as required.

Cryoablation of early-stage breast cancer: work-in-progress report of a multi-institutional trial

BACKGROUND

With recent improvements in breast imaging, our ability to identify small breast tumors has markedly improved, prompting significant interest in the use of ablation without surgical excision to treat early-stage breast cancer. We conducted a multi-institutional pilot safety study of cryoablation in the treatment of primary breast carcinomas.

METHODS

Twenty-nine patients with ultrasound-visible primary invasive breast cancer </=2.0 cm were enrolled. Twenty-seven (93%) successfully underwent ultrasound-guided cryoablation with a tabletop argon gas-based cryoablation system with a double freeze/thaw cycle. Standard surgical resection was performed 1 to 4 weeks after cryoablation. Patients were monitored for complications, and pathology data were used to assess efficacy.

RESULTS

Cryoablation was successfully performed in an office-based setting with only local anesthesia. There were no complications to the procedure or postprocedural pain requiring narcotic pain medications. Cryoablation successfully destroyed 100% of cancers <1.0 cm. For tumors between 1.0 and 1.5 cm, this success rate was achieved only in patients with invasive ductal carcinoma without a significant ductal carcinoma-in-situ (DCIS) component. For unselected tumors >1.5 cm, cryoablation was not reliable with this technique. Patients with noncalcified DCIS were the cause of most cryoablation failures.

CONCLUSIONS

Cryoablation is a safe and well-tolerated office-based procedure for the ablation of early-stage breast cancer. At this time, cryoablation should be limited to patients with invasive ductal carcinoma </=1.5 cm and with <25% DCIS in the core biopsy. A multicenter phase II clinical trial is planned.

Electrical Impedance Tomography of Cell Viability in Tissue With Application to Cryosurgery

Tissue damage that is associated with the loss of cell membrane integrity should alter the bulk electrical properties of the tissue. This study shows that electrical impedance tomography (EIT) should be able to detect and image necrotic tissue inside the body due to the permeabilization of the membrane to ions. Cryosurgery, a minimally invasive surgical procedure that uses freezing to destroy undesirable tissue, was used to investigate the hypothesis. Experimental results with liver tissue demonstrate that cell damage during freezing results in substantial changes in tissue electrical properties. Two-dimensional EIT simulations of liver cryosurgery, which employ the experimental data, demonstrate the feasibility of this application.

Minimally invasive surgery for small breast cancer

BACKGROUND AND METHODS

So-called minimally invasive techniques make percutaneous eradication of breast tumors possible, thus leading to breast-conserving treatment (BCT) without surgery. This paper reviews and discusses the feasibility of minimally invasive techniques for breast cancer.

RESULTS

Although a wide variety of ablation techniques have been investigated for the treatment of primary breast cancer, radiofrequency ablation (RFA) remains one of the most promising and potentially useful tools. RFA therapy results in effective cell killing in a predictable volume of tissue with a low complication rate. On the other hand, ultrasonography is useful for guiding the needle within the tumor but cannot predict the extent of thermal ablation accurately. Early post-procedural magnetic resonance imaging (MRI) may be useful for assessing whether complete tumor ablation has been achieved by RFA. Whether adequate ablation of the tumor has been achieved can be confirmed by extensive core needle sampling of the treated area. However, validation of the margin status is also important and this needs to be tackled in further studies.

CONCLUSIONS

There are many problems that remain before RFA therapy can be considered for conventional treatment. Further studies are needed to determine whether the use of RFA alone for local treatment of primary breast cancer will result in local recurrence and survival rates equivalent to those seen with BCT.

MR imaging-guided focused US ablation of breast cancer: histopathologic assessment of effectiveness-- initial experience

PURPOSE

To evaluate the effectiveness of noninvasive magnetic resonance (MR) imaging-guided focused ultrasonographic (US) ablation of breast carcinomas.

MATERIALS AND METHODS

Before undergoing tumor resection, 12 patients with invasive breast carcinomas were treated with MR imaging-guided focused US ablation consisting of multiple sonications of targeted points that were monitored with temperature-sensitive MR imaging. The patients were treated with either one of two focused US systems. The effectiveness of the treatment was determined at histopathologic analysis of the resected mass that was performed to determine the volumes of necrosed and residual tumor. Complications resulting from the procedure were assessed by means of questionnaires, medical examinations, and MR image analysis.

RESULTS

US ablation was well tolerated by the patients, and with the exception of minor skin burns in two patients, no complications occurred. Histopathologic analysis of resected tumor sections enabled quantification of the amount of necrosed and residual tumor and visualization of the surrounding hemorrhage. In three patients treated with one of the US systems, a mean of 46.7% of the tumor was within the targeted zone and a mean of 43.3% of the cancer tissue was necrosed. In nine patients treated with the other US system, a mean of 95.6% of the tumor was within the targeted zone and a mean of 88.3% of the cancer tissue was necrosed. Residual tumor was identified predominantly at the periphery of the tumor mass; this indicated the need to increase the total targeted area (ie, with an increased number of sonications).

CONCLUSION

Thermal coagulation of small breast tumors by means of MR imaging-guided focused US appears to be a promising noninvasive ablation procedure.

Diffusion-weighted MRI after cryosurgery of the canine prostate. Magnetic resonance imaging

PURPOSE

To evaluate the acute lesion created by cryosurgery with diffusion-weighted magnetic resonance imaging (DWI).

MATERIALS AND METHODS

The appearance of the acute cryolesion was evaluated in four canine prostates DWI after they were warmed to original body temperature. The prostates were excised, stained with triphenyl tetrazolium chloride (TTC), photographed, prepared for hematoxylin and eosin (H&E) staining, and examined under a light microscope.

RESULTS

A marked decrease in apparent diffusion coefficient of 38% was evident in the center of the previously frozen tissue, but not in all of the previously frozen tissue. Histologic results confirm differences between the iceball core and the periphery of the iceball, which have markedly different imaging characteristics on DWI.

CONCLUSION

The core of the previously frozen tissue has a reduced apparent diffusion coefficient (ADC) compared to the periphery of the previously frozen tissue and previously unfrozen tissue.

Treatment of cancer with cryochemotherapy

Cryosurgery employs freezing to destroy solid tumours. However, frozen cells can survive and cause cancer recurrence. Bleomycin, an anticancer drug with a huge intrinsic cytotoxicity is normally not very effective because it is nonpermeant. We report that freezing facilitates bleomycin penetration into cells making it toxic to cryosurgery surviving cells at concentrations that are non-toxic systemically.

Minimally invasive techniques in breast cancer treatment

Breast conservation therapy has largely replaced mastectomy as the surgical treatment of choice for early-stage breast cancer. As the sentinel lymph node mapping procedure, rather than routine axillary node dissection, becomes the standard of care, the next challenge is how to treat the primary tumor without surgery. Minimally invasive ablation of the primary tumor is possible with a variety of approaches; the goal is to either excise the tumor percutaneously or cool it (with cryotherapy) or heat it (with radiofrequency ablation (RFA), focused ultrasound, or laser interstitial therapy) sufficiently to cause complete cell death. These developing technologies may provide treatment options that are psychologically and cosmetically more acceptable to the patient than traditional therapies, but they need further investigation to prove that they are oncologically sound. This new frontier of surgery without scalpels will require surgeons to develop radiologic expertise and to acquire a basic understanding of molecular biology.