Focused microwave phased array thermotherapy for ablation of early-stage breast cancer: results of thermal dose escalation

A two-stage exacerbated hypoxia nanoengineering strategy induced amplifying activation of tirapazamine for microwave hyperthermia-chemotherapy of breast cancer

Microwave hyperthermia (MH) is an emerging treatment for solid tumors, such as breast cancer, due to its advantages of minimally invasive and deep tissue penetration. However, MH induced tumor hypoxia is still an obstacle to breast tumor treatment failure. Therefore, an original nanoengineering strategy was proposed to exacerbate hypoxia in two stages, thereby amplifying the efficiency of activating tirapazamine (TPZ). And a novel microwave-sensitized nanomaterial (GdEuMOF@TPZ, GEMT) is designed. GdEuMOF (GEM) nanoparticles are certified excellent microwave (MW) sensitization performance, thus improving tumor selectivity to achieve MH. Meanwhile MW can aggravate the generation of thrombus and caused local circulatory disturbance of tumor, resulting in the Stage I exacerbated hypoxia environment passively. Due to tumor heterogeneity and uneven hypoxia, GEMT nanoparticles under microwave could actively deplete residual oxygen through the chemical reaction, exacerbating hypoxia level more evenly, thus forming the Stage II of exacerbated hypoxia environment. Consequently, a two-stage exacerbated hypoxia GEMT nanoparticles realize amplifying activation of TPZ, significantly enhance the efficacy of microwave hyperthermia and chemotherapy, and effectively inhibit breast cancer. This research provides insights into the development of progressive nanoengineering strategies for effective breast tumor therapy.

Non-pyrogenic highly pure magnetosomes for efficient hyperthermia treatment of prostate cancer

We report the fabrication of highly pure magnetosomes that are synthesized by magnetotactic bacteria (MTB) using pharmaceutically compatible growth media, i.e., without compounds of animal origin (yeast extracts), carcinogenic, mutagenic, or toxic for reproduction (CMR) products, and other heavy metals than iron. To enable magnetosome medical applications, these growth media are reduced and amended compared with media commonly used to grow these bacteria. Furthermore, magnetosomes are made non-pyrogenic by being extracted from these micro-organisms and heated above 400 °C to remove and denature bacterial organic material and produce inorganic magnetosome minerals. To be stabilized, these minerals are further coated with citric acid to yield M-CA, leading to fully reconstructed chains of magnetosomes. The heating properties and anti-tumor activity of highly pure M-CA are then studied by bringing M-CA into contact with PC3-Luc tumor cells and by exposing such assembly to an alternating magnetic field (AMF) of 42 mT and 195 kHz during 30 min. While in the absence of AMF, M-CA are observed to be non-cytotoxic, they result in a 35% decrease in cell viability following AMF application. The treatment efficacy can be associated with a specific absorption rate (SAR) value of M-CA, which is relatively high in cellular environment, i.e., SAR_cell = 253 ± 11 W/g_Fe, while being lower than the M-CA SAR value measured in water, i.e., SAR_water = 1025 ± 194 W/g_Fe, highlighting that a reduction in the Brownian contribution to the SAR value in cellular environment does not prevent efficient tumor cell destruction with these nanoparticles. KEY POINTS : • Highly pure magnetosomes were produced in pharmaceutically compatible growth media • Non-pyrogenic and stable magnetosomes were prepared for human injection • Magnetosomes efficiently destroyed prostate tumor cells in magnetic hyperthermia.

Percutaneous Management of Breast Cancer: a Systematic Review

PURPOSE OF REVIEW

Surgical treatment of breast cancer is becoming increasingly more minimally invasive. We review the development status of percutaneous management for primary breast cancer and the evidence relating to tumor size as a fundamental determinant of treatment clinical outcome.

RECENT FINDINGS

It is safe and feasible for percutaneous management to treat breast cancer. For tumor size ≤ 2 cm, percutaneous management is a promising alternative modality. For tumor size ≤ 3 cm, it is controversial whether percutaneous management can achieve similar effects to surgery, especially its long-term effects. For tumor size > 3 cm, it is still in the initial exploration stage and showed the potential in the treatment of unresectable cancer by benefitting the local control of primary cancer. Percutaneous management of breast cancer is a valuable method for breast cancer treatment in selected patients. However, it will be necessary to provide the high level of evidence for widespread clinical application.

Thermal Boost Combined with Interstitial Brachytherapy in Early Breast Cancer Conserving Therapy—Initial Group Long-Term Clinical Results and Late Toxicity

(1) In breast-conserving therapy (BCT), adjuvant radiation, including tumor bed boost, is mandatory. Safely delivered thermal boost (TB) based on radio-sensitizing interstitial microwave hyperthermia (MWHT) preceding standard high-dose-rate (HDR) brachytherapy (BT) boost has the potential for local control (LC) improvement. The study is to report the long-term results regarding LC, disease-free survival (DFS), overall survival (OS), toxicity, and cosmetic outcome (CO) of HDR-BT boost ± MWHT for early breast cancer (BC) patients treated with BCT. (2) In the years 2006 and 2007, 57 diverse stages and risk (IA-IIIA) BC patients were treated with BCT ± adjuvant chemotherapy followed by 42.5–50.0 Gy whole breast irradiation (WBI) and 10 Gy HDR-BT boost. Overall, 25 patients (group A; 43.9%) had a BT boost, and 32 (group B; 56.1%) had an additional pre-BT single session of interstitial MWHT on a tumor bed. Long-term LC, DFS, OS, CO, and late toxicity were evaluated. (3) Median follow-up was 94.8 months (range 1.1–185.5). LC was 55/57, or 96.5% (1 LR in each group). DFS was 48/57, or 84.2% (4 failures in group A, 5 in B). OS was 46/57, or 80.7% (6 deaths in group A, 5 in B). CO was excellent in 60%, good in 36%, and satisfactory in 4% (A), and in 53.1%, 34.4%, and 9.4% (B), respectively. One poor outcome was noted (B). Late toxicity as tumor bed hardening occurred in 19/57, or 33.3% of patients (9 in A, 10 in B). In one patient, grade 2 telangiectasia occurred (group A). All differences were statistically insignificant. (4) HDR-BT boost ± TB was feasible, well-tolerated, and highly locally effective. LC, DFS, and OS were equally distributed between the groups. Pre-BT MWHT did not increase rare late toxicity.

Liver cancer treatment with integration of laser emission and microwave irradiation with the aid of gold nanoparticles

This paper studies the effectiveness of the integration of microwave field irradiation and laser emission in liver cancer therapy with the aid of gold nanorods, in order to find out the influences of these combinational methods in tumor necrosis. Hepatocellular carcinoma is a kind of liver cancer that usually has a complicated structure, including both of superficial and deep sections. In current research, in deep regions of cancerous tissue, microwave antenna is utilized and in superficial regions, laser beams are irradiated. A Pulsed laser with heating time of 50 s and cooling time of 20 s is utilized for hyperthermia treatment. It should be mentioned that gold nanorods are injected into the tumorous region to enhance the treatment process and reduce the patient’s exposure time. Simulation results showed that at the first step, without any injection of gold nanoparticles, 0.17% of the tumor’s volume encountered necrosis, while at the next stage, after injection of gold nanorods, the necrosis rate increased to 35%, which demonstrates the efficiency of gold nanorods injection on the tumor treatments. Furthermore, the combinational applying of both microwave antenna and laser illumination can eradiate the tumor tissue completely.

Thermal Boost to Breast Tumor Bed—New Technique Description, Treatment Application and Example Clinical Results

(1) Current breast-conserving therapy for breast cancer consists of a combination of many consecutive treatment modalities. The most crucial goal of postoperative treatment is to eradicate potentially relapse-forming residual cancerous cells within the tumor bed. To achieve this, the HDR brachytherapy boost standardly added to external beam radiotherapy was enhanced with an initial thermal boost. This study presents an original thermal boost technique developed in the clinic. (2) A detailed point-by-point description of thermal boost application is presented. Data on proper patient selection, microwave thermal boost planning, and interstitial hyperthermia treatment delivery are supported by relevant figures and schemes. (3) Out of 1134 breast cancer patients who were administered HDR brachytherapy boost in the tumor bed, 262 were also pre-heated interstitially without unexpected complications. The results are supported by two example cases of hyperthermia planning and delivery. (4) Additional breast cancer interstitial thermal boost preceding HDR brachytherapy boost as a part of combined treatment in a unique postoperative setting was feasible, well-tolerated, completed in a reasonable amount of time, and reproducible. A commercially available interstitial hyperthermia system fit and worked well with standard interstitial brachytherapy equipment.

Quo Vadis Oncological Hyperthermia (2020)?

Heating as a medical intervention in cancer treatment is an ancient approach, but effective deep heating techniques are lacking in modern practice. The use of electromagnetic interactions has enabled the development of more reliable local-regional hyperthermia (LRHT) techniques whole-body hyperthermia (WBH) techniques. Contrary to the relatively simple physical-physiological concepts behind hyperthermia, its development was not steady, and it has gone through periods of failures and renewals with mixed views on the benefits of heating seen in the medical community over the decades. In this review we study in detail the various techniques currently available and describe challenges and trends of oncological hyperthermia from a new perspective. Our aim is to describe what we believe to be a new and effective approach to oncologic hyperthermia, and a change in the paradigm of dosing. Physiological limits restrict the application of WBH which has moved toward the mild temperature range, targeting immune support. LRHT does not have a temperature limit in the tumor (which can be burned out in extreme conditions) but a trend has started toward milder temperatures with immune-oriented goals, developing toward immune modulation, and especially toward tumor-specific immune reactions by which LRHT seeks to target the malignancy systemically. The emerging research of bystander and abscopal effects, in both laboratory investigations and clinical applications, has been intensified. Our present review summarizes the methods and results, and discusses the trends of hyperthermia in oncology.

The role of device-assisted therapies in the management of non-muscle invasive bladder cancer: A systematic review

OBJECTIVE

Despite optimal treatment, patients affected by non-muscle invasive bladder cancer (NMIBC) suffer from high risk of recurrence and progression. Intravescical device assisted therapies such as radiofrequency induced thermochemotherapeutic effect (RITE) and electromotive drug administration (EMDA) have shown promising effect in enhancing the effect of intravescical chemotherapies. The aim of the study was to assess clinical outcomes of these two devices in non-muscle invasive bladder cancer.

METHODS

A systematic literature review was performed in December 2019 using the Medline, Embase, and Web of Science databases. Only articles published in the last 10 years were considered (2009-2019). The articles were selected using the following keywords association: "bladder cancer" AND "EMDA' AND "synergo" AND "hyperchemotherapy" AND "electromotive drug administration", AND "radiofrequency induced thermochemotherapeutic" AND "RITE".

RESULTS

We found 16 studies published in the last ten years regarding the efficacy of RITE (12 studies) and EMDA (4 studies) in the treatment of NMIBC. Both RITE and EMDA showed promising results in the treatment of intermediate and high risk NMIBC as well as in patients affected by recurrent BCa after BCG failure. In high-risk BCG naïve NMIBC patients treated with EMDA recurrence and progression rates were 68% and 95%, respectively. Considering RITE, recurrence and progression range rates were 43%-88% and 62%-97%, respectively. Discordance results were reported regarding its effect on patients with carcinoma in situ. However, only few studies could be compared since differences exist regarding inclusion criteria with high patients' heterogeneity. Considering recurrence after BCG, recurrence and progression range rates were 29%-29.2% and 62%-83% for RITE and 25% and 75% for EMDA, respectively.

CONCLUSION

Delivery of intravescical hyperthermia seems to enhance the normal effect of intravescical chemotherapy instillation. Although prospective trials supported its effect on both BCG naïve and BCG failure patients, data are urgently required to validate these findings and to understand its effect on patients with carcinoma in situ.

LEVEL OF PROOF

3.

Enhancement of Photodynamic Cancer Therapy by Physical and Chemical Factors

The viable use of photodynamic therapy (PDT) in cancer therapy has never been fully realized because of its undesirable effects on healthy tissues. Herein we summarize some physicochemical factors that can make PDT a more viable and effective option to provide future oncological patients with better-quality treatment options. These physicochemical factors include light sources, photosensitizer (PS) carriers, microwaves, electric fields, magnetic fields, and ultrasound. This Review is meant to provide current information pertaining to PDT use, including a discussion of in vitro and in vivo studies. Emphasis is placed on the physicochemical factors and their potential benefits in overcoming the difficulty in transitioning PDT into the medical field. Many advanced techniques, such as employing X-rays as a light source, using nanoparticle-loaded stem cells and bacteriophage bio-nanowires as a photosensitizer carrier, as well as integration with immunotherapy, are among the future directions.

Intravesical device-assisted therapies for non-muscle-invasive bladder cancer

Non-muscle-invasive bladder cancer (NMIBC), the most prevalent type of bladder cancer, accounts for ~75% of bladder cancer diagnoses. This disease has a 50% risk of recurrence and 20% risk of progression within 5 years, despite the use of intravesical adjuvant treatments (such as BCG or mitomycin C) that are recommended by clinical guidelines. Intravesical device-assisted therapies, such as radiofrequency-induced thermochemotherapeutic effect (RITE), conductive hyperthermic chemotherapy, and electromotive drug administration (EMDA), have shown promising efficacy. These device-assisted treatments are an attractive alternative to BCG, as issues with supply have been a problem in some countries. RITE might be an effective treatment option for some patients who have experienced BCG failure and are not candidates for radical cystectomy. Data from trials using EMDA suggest that it is effective in high-risk disease but requires further validation, and results of randomized trials are eagerly awaited for conductive hyperthermic chemotherapy. Considerable heterogeneity in patient cohorts, treatment sessions, use of maintenance regimens, and single-arm study design makes it difficult to draw solid conclusions, although randomized controlled trials have been reported for RITE and EMDA.

Heat Stress-Induced Multiple Multipolar Divisions of Human Cancer Cells

Multipolar divisions of heated cells has long been thought to stem from centrosome aberrations of cells directly caused by heat stress. In this paper, through long-term live-cell imaging, we provide direct cellular evidences to demonstrate that heat stress can promote multiple multipolar divisions of MGC-803 and MCF-7 cells. Our results show that, besides facilitating centrosome aberration, polyploidy induced by heat stress is another mechanism that causes multipolar cell divisions, in which polyploid cancer cells engendered by mitotic slippage, cytokinesis failure, and cell fusion. Furthermore, we also find that the fates of theses polyploid cells depend on their origins, in the sense that the polyploid cells generated by mitotic slippage experience bipolar divisions with a higher rate than multipolar divisions, while those polyploid cells induced by both cytokinesis failure and cell fusion have a higher frequency of multipolar divisions compared with bipolar divisions. This work indicates that heat stress-induced multiple multipolar divisions of cancer cells usually produce aneuploid daughter cells, and might lead to genetically unstable cancer cells and facilitate tumor heterogeneity.

Clinical application of ultrasound-guided percutaneous microwave ablation for benign breast lesions: a prospective study

BACKGROUND

Background: Benign breast lesions are the most common diseases in adult women, which have been treated with minimally invasive therapies in recent years. Little is known about the feasibility of Microwave ablation (MWA) for benign breast lesion treatment. The primary aim of this prospective study was to evaluate the safety and efficiency of MWA as a potential therapeutic option for benign breast lesions in a single-center cohort study.

METHODS

Women with possibly benign breast lesions based on an ultrasound (US) assessment who were scheduled to undergo MWA between November 2014 to July 2018 were included in the study. The patients underwent conventional US to measure the size of the lesion, Doppler US to assess the vascularity of the lesion, elastography to evaluate the stiffness of the mass, core needle biopsy of suspicious lesions, contrast-enhanced US to help determine the treatment plan and eventually MWA of the lesion. Lesions were followed at one, three, six, twelve and eighteen months after treatment to with the same imaging modalities.

RESULTS

A total of 314 women aged 17 to 69 years old (mean = 36.9 ± 9.9 years) with 725 benign breast lesions (mean of maximum diameter = 10.86 ± 5.40 mm) were included. The frequency of palpable mass, pain and nipple discharge significantly decreased after treatment. Complete ablation rate was 97.8%, immediately after ablation, which increased to 100% after supplementary ablation of the 15 cases with incomplete ablation. Blood flow classification and lesion's volume also showed a significant decrease, while both volume reduction ratio and disappearance rate significantly increased following treatment. The elasticity score of the lesions showed fluctuations across different follow-up intervals. None of the patients experienced major complications and the 1% who had mild symptoms were successfully treated.

CONCLUSION

MWA treatment is shown to be safe and efficient and has the potential to be considered as an alternative first line treatment for benign breast lesions.

Computational FEM Model, Phantom and Ex Vivo Swine Breast Validation of an Optimized Double-Slot Microcoaxial Antenna Designed for Minimally Invasive Breast Tumor Ablation: Theoretical and Experimental Comparison of Temperature, Size of Lesion, and SWR, Preliminary Data

Malignant neoplasms are one of the principal world health concerns and breast cancer is the most common type of cancer in women. Advances in cancer detection technologies allow treating it in early stages; however, it is necessary to develop treatments which carry fewer complications and aesthetic repercussions. This work presents a feasibility study for the use of microwave ablation as a novel technique for breast cancer treatment. A microwave applicator design is also being proposed for this purpose. The coupling of the designed antenna was predicted with computer simulation. The standing wave ratio obtained through simulation was 1.87 and the result of experimental validation was 1.04. The optimized antenna has an optimal coupling (SWR = 1.04) so ablation temperatures can be achieved in a relatively short time using low power. Varying the time and power, the heating pattern can be changed to treat different tumors. However, as some discrepancies are still present, a deeper study of the dielectric properties and their variation with temperature is required.

Ultrasound-guided percutaneous microwave ablation for benign breast lesions: evaluated by contrast-enhanced ultrasound combined with magnetic resonance imaging

Background

Minimally invasive ablative techniques in the treatment of breast tumor has become popularly in recent years.

Methods

We analyzed gray-scale and contrast-enhanced ultrasound (CEUS) features of 205 microwave ablated breast benign lesions from 182 consecutive patients, compared with magnetic resonance imaging (MRI) and histopathology findings. The follow-up was implemented at 3, 6 and 12 months after the ablation treatment.

Results

Before the MWA, the mean of largest diameter and volume of the lesions were 14.41±6.54 and 3,224±961 mm³, respectively. However, those of the lesions respectively were 8.48±6.30 and 2,116±732 mm³ one year after the treatment. The longest diameter and the volume of the ablative lesions were gradually decreased 3, 6 or 12 months after the MWA. 44 (/205, 21.5%) ablative lesions were disappeared one year after the MWA. One hundred and forty-two (/205, 69.3%) ablative lesions presented a hypoechoic halo surrounding it on gray-scale US after the MWA. The success rate of the MWA treatment in the benign breast lesion was 87.32% and 82.93% evaluated by CEUS and enhanced MRI, respectively. During the ablation, no patient had serious complications, such as hemorrhage, serious pain and fat necrosis, etc.

Conclusions

Microwave ablation was a safe and efficient method in the treatment of the benign breast tumors. CEUS and enhanced MRI could accurately assess whether the MWA treatment is effective.

New experimental model for single liver lobe hyperthermia in small animals using non-directional microwaves

PURPOSE

Our aim was to develop a new experimental model for in vivo hyperthermia using non-directional microwaves, applicable to small experimental animals. We present an affordable approach for targeted microwave heat delivery to an isolated liver lobe in rat, which allows rapid, precise and stable tissue temperature control.

MATERIALS AND METHODS

A new experimental model is proposed. We used a commercial available magnetron generating 2450 MHz, with 4.4V and 14A in the filament and 4500V anodic voltage. Modifications were required in order to adjust tissue heating such as to prevent overheating and to allow for fine adjustments according to real-time target temperature. The heating is controlled using a virtual instrument application implemented in LabView® and responds to 0.1° C variations in the target. Ten healthy adult male Wistar rats, weighing 250-270 g were used in this study. The middle liver lobe was the target for controlled heating, while the rest of the living animal was protected.

RESULTS

In vivo microwave delivery using our experimental setting is safe for the animals. Target tissue temperature rises from 30°C to 40°C with 3.375°C / second (R2 = 0.9551), while the increment is lower it the next two intervals (40-42°C and 42-44°C) with 0.291°C/ s (R2 = 0.9337) and 0.136°C/ s (R2 = 0.7894) respectively, when testing in sequences. After reaching the desired temperature, controlled microwave delivery insures a very stable temperature during the experiments.

CONCLUSIONS

We have developed an inexpensive and easy to manufacture system for targeted hyperthermia using non-directional microwave radiation. This system allows for fine and stable temperature adjustments within the target tissue and is ideal for experimental models testing below or above threshold hyperthermia.

Equivalence of cell survival data for radiation dose and thermal dose in ablative treatments: analysis applied to essential tremor thalamotomy by focused ultrasound and gamma knife

Thermal dose and absorbed radiation dose have historically been difficult to compare because different biological mechanisms are at work. Thermal dose denatures proteins and the radiation dose causes DNA damage in order to achieve ablation. The purpose of this paper is to use the proportion of cell survival as a potential common unit by which to measure the biological effect of each procedure. Survival curves for both thermal and radiation doses have been extracted from previously published data for three different cell types. Fits of these curves were used to convert both thermal and radiation dose into the same quantified biological effect: fraction of surviving cells. They have also been used to generate and compare survival profiles from the only indication for which clinical data are available for both focused ultrasound (FUS) thermal ablation and radiation ablation: essential tremor thalamotomy. All cell types could be fitted with coefficients of determination greater than 0.992. As an illustration, survival profiles of clinical thalamotomies performed by radiosurgery and FUS are plotted on a same graph for the same metric: fraction of surviving cells. FUS and Gamma Knife have the potential to be used in combination to deliver a more effective treatment (for example, FUS may be used to debulk the main tumour mass, and radiation to treat the surrounding tumour bed). In this case, a model which compares thermal and radiation treatments is valuable in order to adjust the dose between the two.

Ultrasound guided percutaneous microwave ablation of benign breast lesions

The benign breast lesions (BBLs) share a high incidence for women and therapy methods with minimal invasion and better cosmetic outcome are thirsted for. In this study, 122 patients with 198 biopsy-proved BBLs were enrolled. Ultrasound (US)-guided microwave ablation (MWA) was performed with local anesthesia from November, 2013 to April, 2016. The mean longest tumor size assessed was 1.6±0.7 cm (ranging 0.7-4.9 cm). MWA was successfully performed in all cases including 85 lesions adjacent to the skin, pectoralis and areola. The mean ablation time was 3.2mins (ranging 0.5-18.3 mins). 99.5% of BBLs showed complete ablation when assessed by magnetic resonance imaging and 100% of them by US. At the median 14-month follow-up, the BBLs were not palpable in 45.9 % of the cases (palpable in 90.2 % of the cases before MWA) and the mean volume reduction ratio was 78.4±33.5% for total lesions and 89.3±20.8%, 84.7±27.6% and 55.9±32.9% for ≤1.0 cm, 1.1-2.0cm and >2.0 cm lesions in 12-month follow-up, respectively. Cosmesis were reported as good or excellent in 100 % by physician and patients. No side effect was found. The MWA of the BBLs proved feasible and effective, while showing meaningful reduction in volume, palpability and cosmetic satisfying outcomes.

Real-Time Three-Dimensional Microwave Monitoring of Interstitial Thermal Therapy

We report a method for real-time three-dimensional monitoring of thermal therapy through the use of noncontact microwave imaging. This method is predicated on using microwaves to image changes in the dielectric properties of tissue with changing temperature. Instead of the precomputed linear Born approximation that was used in prior work to speed up the frame-to-frame inversions, here we use the nonlinear distorted Born iterative method (DBIM) to solve the electric volume integral equation (VIE) to image the temperature change. This is made possible by using a recently developed graphic processing unit accelerated conformal finite difference time domain method to solve the forward problem and update the electric field in the monitored region in each DBIM iteration. Compared to our previous work, this approach provides a far superior approximation of the electric field within the VIE, and thus yields a more accurate reconstruction of tissue temperature change. The proposed method is validated using a realistic numerical model of interstitial thermal therapy for a deep-seated brain lesion. With the new DBIM, we reduced the average estimation error of the mean temperature within the region of interest from 2.5 to 1.0 for the noise-free case, and from 2.9 to 1.7 for the 2% background noise case.

Long-term efficacy of ultrasound-guided high-intensity focused ultrasound treatment of breast fibroadenoma

BACKGROUND

To assess the long term efficacy and tolerability of one or two ultrasound (US)-guided high-intensity focused ultrasound (HIFU) treatment in patients with breast fibroadenoma (FA).

METHODS

Twenty patients with 26 FA were selected for US-guided HIFU. The therapy was performed in one or two sessions. FA volume was assessed before and followed up to 24 months after the last HIFU. After each treatment, adverse events were evaluated.

RESULTS

In 19/26 FA (73.1%) one HIFU was performed (group 1), whereas 7/26 FA (26.9%) received second HIFU (group 2) 6-9 months (median, 7 months) after the first session. In group 1 and 2, FA volume decreased significantly at 1-month (p < 0.001) and 3-month follow-up (p = 0.005), respectively, and continued to reduce until 24-month follow-up (p < 0.001 and p = 0.003, respectively). At 24 months, mean volume reduction was 77.32% in group 1 and 90.47% in group 2 (p = 0.025). Mild subcutaneous edema was observed in 4 patients and skin erythema in 3 patients.

CONCLUSIONS

US-guided HIFU represents a promising non-invasive method with sustainable FA volume reduction and patient's tolerability. Although one treatment is highly efficient, the volume reduction can be increased with second treatment.

TRIAL REGISTRATION

NCT01331954. Registered 07 April 2011.

Technical success, technique efficacy and complications of minimally-invasive imaging-guided percutaneous ablation procedures of breast cancer: A systematic review and meta-analysis

OBJECTIVES

To systematically review studies concerning imaging-guided minimally-invasive breast cancer treatments.

METHODS

An online database search was performed for English-language articles evaluating percutaneous breast cancer ablation. Pooled data and 95% confidence intervals (CIs) were calculated. Technical success, technique efficacy, minor and major complications were analysed, including ablation technique subgroup analysis and effect of tumour size on outcome.

RESULTS

Forty-five studies were analysed, including 1,156 patients and 1,168 lesions. Radiofrequency (n=577; 50%), microwaves (n=78; 7%), laser (n=227; 19%), cryoablation (n=156; 13%) and high-intensity focused ultrasound (HIFU, n=129; 11%) were used. Pooled technical success was 96% (95%CI 94-97%) [laser=98% (95-99%); HIFU=96% (90-98%); radiofrequency=96% (93-97%); cryoablation=95% (90-98%); microwave=93% (81-98%)]. Pooled technique efficacy was 75% (67-81%) [radiofrequency=82% (74-88); cryoablation=75% (51-90); laser=59% (35-79); HIFU=49% (26-74)]. Major complications pooled rate was 6% (4-8). Minor complications pooled rate was 8% (5-13%). Differences between techniques were not significant for technical success (p=0.449), major complications (p=0.181) or minor complications (p=0.762), but significant for technique efficacy (p=0.009). Tumour size did not impact on variables (p>0.142).

CONCLUSIONS

Imaging-guided percutaneous ablation techniques of breast cancer have a high rate of technical success, while technique efficacy remains suboptimal. Complication rates are relatively low.

KEY POINTS

• Imaging-guided ablation techniques for breast cancer are 96% technically successful. • Overall technique efficacy rate is 75% but largely inhomogeneous among studies. • Overall major and minor complication rates are low (6-8%).

Minimally invasive ablative techniques in the treatment of breast cancer: a systematic review and meta-analysis

PURPOSE

Breast-conserving surgery is effective for breast cancer treatment but is associated with morbidity in particular high re-excision rates. We performed a systematic review and meta-analysis to assess the current evidence for clinical outcomes with minimally invasive ablative techniques in the non-surgical treatment of breast cancer.

METHODS

A systematic search of the literature was performed using PubMed and Medline library databases to identify all studies published between 1994 and May 2016. Studies were considered eligible for inclusion if they evaluated the role of ablative techniques in the treatment of breast cancer and included ten patients or more. Studies that failed to fulfil the inclusion criteria were excluded.

RESULTS

We identified 63 studies including 1608 patients whose breast tumours were treated with radiofrequency (RFA), high intensity focussed ultrasound (HIFU), cryo-, laser or microwave ablation. Fifty studies reported on the number of patients with complete ablation as found on histopathology and the highest rate of complete ablation was achieved with RFA (87.1%, 491/564) and microwave ablation (83.2%, 89/107). Short-term complications were most often reported with microwave ablation (14.6%, 21/144). Recurrence was reported in 24 patients (4.2%, 24/570) and most often with laser ablation (10.7%, 11/103). The shortest treatment times were observed with RFA (15.6 ± 5.6 min) and the longest with HIFU (101.5 ± 46.6 min).

CONCLUSION

Minimally invasive ablative techniques are able to successfully induce coagulative necrosis in breast cancer with a low side effect profile. Adequately powered and prospectively conducted cohort trials are required to confirm complete pathological ablation in all patients.

Temperature responsive porous silicon nanoparticles for cancer therapy - spatiotemporal triggering through infrared and radiofrequency electromagnetic heating

One critical functionality of the carrier system utilized in targeted drug delivery is its ability to trigger the release of the therapeutic cargo once the carrier has reached its target. External triggering is an alluring approach as it can be applied in a precise spatiotemporal manner. In the present study, we achieved external triggering through the porous silicon (PSi) nanoparticles (NPs) by providing a pulse of infrared or radiofrequency radiation. The NPs were grafted with a temperature responsive polymer whose critical temperature was tailored to be slightly above 37°C. The polymer coating improved the biocompatibility of the NPs significantly in comparison with their uncoated counterparts. Radiation induced a rapid temperature rise, which resulted in the collapse of the polymer chains facilitating the cargo release. Both infrared and radiofrequency radiation were able to efficiently trigger the release of the encapsulated drug in vitro and induce significant cell death in comparison to the control groups. Radiofrequency radiation was found to be more efficient in vitro, and the treatment efficacy was verified in vivo in a lung carcinoma (3LL) mice model. After a single intratumoral administration of the carrier system combined with radiofrequency radiation, there was clear suppression of the growth of the carcinoma and a prolongation of the survival time of the animals.

TOC IMAGE

The temperature responsive (TR) polymer grafted on the surface of porous silicon nanoparticles (PSi NPs) changes its conformation in response to the heating induced by infrared or radiofrequency radiation. The conformation change allows the loaded doxorubicin to escape from the pores, achieving controlled drug release from TR PSi NPs, which displayed efficacy against malignant cells both in vitro and in vivo.

Design, development and microwave inter-comparison of dual slot antenna configurations for localized hepatic tumor management

Slot antennas are generally preferred for localized liver cancer treatment modalities due to desired radiation characteristics. An iterative thermal/microwave numerical routine is used to analyze regular and miniature slot antenna configurations at 5.8 GHz. A thermal/microwave solver determines the specific absorption rate to malignant tissues as a pre- processing step to compute microwave solution in terms of propagation wave number, return loss and insertion loss. The regular and miniature dual slots antenna geometries were then developed to estimate the return loss characteristics against antennas slot lengths at a constant frequency of 5.8 GHz. Results reveal that the regular geometry has return loss less than -5 dB as compared to <-25 dB return loss for miniature slot antenna configuration. Furthermore, 5.8 GHz antenna geometry provides physical size reduction up to 50 %, lower fabrication cost and is a better minimally invasive choice due to further packed thermal ablation spots.

Surgical treatment of nonpalpable primary invasive and in situ breast cancer

Breast cancer is the most-common cancer among women worldwide, and over one-third of all cases diagnosed annually are nonpalpable at diagnosis. The increasingly widespread implementation of breast-screening programmes, combined with the use of advanced imaging modalities, such as magnetic resonance imaging (MRI), will further increase the numbers of patients diagnosed with this disease. The current standard management for nonpalpable breast cancer is localized surgical excision combined with axillary staging, using sentinel-lymph-node biopsy in the clinically and radiologically normal axilla. Wire-guided localization (WGL) during mammography is a method that was developed over 40 years ago to enable lesion localization preoperatively; this technique became the standard of care in the absence of a better alternative. Over the past 20 years, however, other technologies have been developed as alternatives to WGL in order to overcome the technical and outcome-related limitations of this technique. This Review discusses the techniques available for the surgical management of nonpalpable breast cancer; we describe their advantages and disadvantages, and highlight future directions for the development of new technologies.

Image-guided ablation in breast cancer treatment

In the past 2 decades, new and improved imaging technologies and the use of breast cancer screening have led to the detection of smaller and earlier-stage breast cancers. Furthermore, there has been a trend toward less aggressive treatment of small breast cancers, which has led to the development of less invasive alternatives than surgery with promising effectiveness, and less morbidity. Many patients are not satisfied with the cosmetic outcome after breast-conservation therapy. Better cosmesis can be achieved with less invasive techniques. Moreover, less aggressive treatment options would be very useful in patients older than 70 years with comorbidities that make surgery a difficult and sometimes life-threatening treatment. Minimally invasive ablation techniques have been studied in early-stage small tumors with the goal of attaining efficacy similar to that of breast-conservation therapy. These techniques would have less scarring and pain, lower costs, better preservation of breast tissue, superior cosmesis, and faster recovery time. Breast lesions can be destroyed by thermal methods, that is, by heating or freezing the tissue. There are 5 types of thermal ablations that have been or currently are in research clinical trials: cryoablation, radiofrequency, laser, microwave, and high-intensity focused ultrasound ablation. The first 4 methods destroy cancers using percutaneous image-guided probe placement. High-intensity focused ultrasound is noninvasive, performed without any skin opening.

Percutaneous image-guided ablation of breast tumors: an overview

Percutaneous non-surgical image-guided ablation is emerging as an adjunct or alternative to surgery in the management of benign and malignant breast tumors. This review covers the current state of the literature regarding percutaneous image-guided ablation modalities, clinical factors regarding patient selection, and future directions for research.

Comparison of magnetic nanoparticle and microwave hyperthermia cancer treatment methodology and treatment effect in a rodent breast cancer model

PURPOSE

The purpose of this study was to compare the efficacy of iron oxide/magnetic nanoparticle hyperthermia (mNPH) and 915 MHz microwave hyperthermia at the same thermal dose in a mouse mammary adenocarcinoma model.

MATERIALS AND METHODS

A thermal dose equivalent to 60 min at 43 °C (CEM60) was delivered to a syngeneic mouse mammary adenocarcinoma flank tumour (MTGB) via mNPH or locally delivered 915 MHz microwaves. mNPH was generated with ferromagnetic, hydroxyethyl starch-coated magnetic nanoparticles. Following mNP delivery, the mouse/tumour was exposed to an alternating magnetic field (AMF). The microwave hyperthermia treatment was delivered by a 915 MHz microwave surface applicator. Time required for the tumour to reach three times the treatment volume was used as the primary study endpoint. Acute pathological effects of the treatments were determined using conventional histopathological techniques.

RESULTS

Locally delivered mNPH resulted in a modest improvement in treatment efficacy as compared to microwave hyperthermia (p = 0.09) when prescribed to the same thermal dose. Tumours treated with mNPH also demonstrated reduced peritumoral normal tissue damage.

CONCLUSIONS

Our results demonstrate similar tumour treatment efficacy when tumour heating is delivered by locally delivered mNPs and 915 MHz microwaves at the same measured thermal dose. However, mNPH treatments did not result in the same type or level of peritumoral damage seen with the microwave hyperthermia treatments. These data suggest that mNP hyperthermia is capable of improving the therapeutic ratio for locally delivered tumour hyperthermia. These results further indicate that this improvement is due to improved heat localisation in the tumour.

Cryosurgery in the treatment of women with breast cancer-a review

Cryoablation could be an alternative to surgical excision of breast cancer. The cytotoxic potential of cryosurgery has been shown in both animal models and studies conducted on humans. There are several advantages to be gained from ablation performed at very low temperatures and these include the method's simplicity, lack of pain, low morbidity, cost-effectiveness, and potential for positive cryo-immunologic effects. This manuscript reviews data concerning the use of cryoablation in the treatment of 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.

High-intensity focused ultrasound ablation of breast cancer

The noninvasive ablation of tumors with high-intensity focused ultrasound (HIFU) energy has received increasingly widespread interest. The temperature within the focal volume of an ultrasound beam is rapidly raised to cytotoxic levels. HIFU can selectively ablate a targeted tumor at depth without any damage to surrounding or overlying tissues. Animal studies have shown that HIFU ablation is safe and effective for the treatment of implanted breast malignancies. The results from early clinical trials (Phase I and II) are encouraging, suggesting that HIFU is a promising treatment for small breast cancer. Once oncologic efficacy data from large-scale randomized clinical trials are available, HIFU ablation may become an attractive treatment option for patients with small breast cancer, especially the elderly.

Contrast ultrasound-guided photothermal therapy using gold nanoshelled microcapsules in breast cancer

OBJECTIVES

The purpose of this study was to test whether dual functional gold nano-shelled microcapsules (GNS-MCs) can be used as an ultrasound imaging enhancer and as an optical absorber for photothermal therapy (PTT) in a rodent model of breast cancer.

METHODS

GNS-MCs were fabricated with an inner air and outer gold nanoshell spherical structure. Photothermal cytotoxicity of GNS-MCs was tested with BT474 cancer cells in vitro and non-obese diabetes-SCID (NOD/SCID) mice with breast cancer. GNS-MCs were injected into the tumor under ultrasound guidance and treated with near-infrared (NIR) laser irradiation. The photothermal ablative effectiveness of GNS-MCs was evaluated by measuring the surface and internal temperature of the tumor as well as the size of the tumor using histological confirmation.

RESULTS

NIR laser irradiation resulted in significant tumor cell death in GNS-MCs-treated BT474 cells in vitro. GNS-MCs were able to serve as an ultrasound enhancer to guide the intratumoral injection of GNS-MCs and ensure their uniform distribution. In vivo studies revealed that NIR laser irradiation increased the intratumoral temperature to nearly 70°C for 8 min in GNS-MCs-treated mice. Tumor volumes decreased gradually and tumors were completely ablated in 6 out of 7 mice treated with GNS-MCs and laser irradiation by 17 days after treatment.

CONCLUSION

This study demonstrates that ultrasound-guided PTT with theranostic GNS-MCs is a promising technique for in situ treatment of breast cancer.

Image-guided tumor ablation: emerging technologies and future directions

As the trend continues toward the decreased invasiveness of medical procedures, image-guided percutaneous ablation has begun to supplant surgery for the local control of small tumors in the liver, kidney, and lung. New ablation technologies, and refinements of existing technologies, will enable treatment of larger and more complex tumors in these and other organs. At the same time, improvements in intraprocedural imaging promise to improve treatment accuracy and reduce complications. In this review, the latest advancements in clinical and experimental ablation technologies will be summarized, and new applications of image-guided tumor ablation will be discussed.

Percutaneous microwave coagulation for eradication of VX2 tumors subcutaneously in rabbits

BACKGROUND

Percutaneous microwave coagulation (PMC) has been accepted as a promising modality in the treatment of tumors in well-vascularized tissues such as liver tumors and hysteromyoma. However, PMC for treatment of tumors in low blood-flow tissues has been seldom reported. The aim of this study was to determine the feasibility and safety of PMC for the treatment of tumors in low blood-flow tissues in a rabbit model.

METHODS

Fifteen rabbits with VX2 tumors implanted subcutaneously underneath the right second nipple were divided into a PMC group (n = 9) and a control group (n = 6). PMC was performed with output power of 40 W for one to two minutes. The therapeutic efficacy was evaluated by magnetic resonance imaging (MRI), physical examinations, survival rate, and histology. The cosmetic outcome after PMC was also assessed.

RESULTS

In the PMC group, tumor eradication was achieved in six rabbits (66.7%) without any evidence of tumor recurrence and metastasis as proven by MRI and histological examinations. The mean greatest and shortest tumor diameters of these six rabbits were 1.83 and 1.33 cm, respectively. Slight epidermal burns, which proved reversible, were found in seven rabbits (77.8%). The PMC group had a significantly longer survival than those in the control group (P = 0.0097). The four rabbits with coagulated tumors survived more than three months with their tumors becoming nonpalpable and undetectable by MRI and histological examinations.

CONCLUSIONS

PMC is feasible and safe in the treatment of tumors in low blood-flow tissues in a rabbit model. Attention should be paid to avoid skin burns with PMC.

A preclinical system prototype for focused microwave thermal therapy of the breast

A preclinical prototype of a transcutaneous thermal therapy system has been developed for the targeted treatment of breast cancer cells using focused microwaves as an adjuvant to radiation, chemotherapy, and high-intensity-focused ultrasound. The prototype system employs a 2-D array of tapered microstrip patch antennas operating at 915 MHz to focus continuous-wave microwave energy transcutaneously into the pendent breast suspended in a coupling medium. Prior imaging studies are used to ascertain the material properties of the breast tissue, and these data are incorporated into a multiphysics model. Time-reversal techniques are employed to find a solution (relative amplitudes and phase) for focusing at a given location. Modeling tests of this time-reversal focusing method have been performed, which demonstrate good targeting accuracy within heterogeneous breast tissue. Experimental results using the laboratory prototype to perform focused heating in tissue-mimicking gelatin phantoms have demonstrated 1.5-cm-diameter focal spot sizes and differential heating at the desired focus sufficient to achieve an antitumor effect confined to the target region.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

US-guided percutaneous microwave coagulation of small breast cancers: a clinical study

PURPOSE

To determine the feasibility of percutaneous microwave coagulation (PMC) for the treatment of small solitary breast cancers.

MATERIALS AND METHODS

With approval of the institutional ethics committee and written informed consent, 41 patients with core-needle-biopsy-proved breast cancers 3.0 cm or less in diameter accessed by using ultrasonography (US) were recruited. US-guided PMC was performed with general anesthesia, followed immediately by mastectomy. Histochemical staining with α-nicotinamide adenine dinucleotide, reduced (NADH)-diaphorase was used to determine cell viability and the extent of PMC lesions.

RESULTS

The mean tumor volume was 5.26 cm(3) ± 3.80 (standard deviation), with a range from 0.09 to 14.14 cm(3). PMC was successfully performed in all cases, with complete tumor ablation as assessed by using US. The mean time to reach complete ablation was 4.48 minutes, ranging from 3 to 10 minutes. With microscopic examination, 37 of 41 cases (90%; 95% confidence interval [CI]: 76.9%, 97.3%) showed complete tumor coagulation, as observed by using α-NADH-diaphorase staining. Of 38 cases diagnosed with invasive ductal carcinoma, 36 cases (95%; 95% CI: 82.3%, 99.4%) showed complete tumor coagulation. Slight thermal injuries to the skin and pectoralis major muscle, which proved reversible, were found in three cases.

CONCLUSION

US-guided PMC of small solitary breast cancers is feasible. Nevertheless, larger-scale clinical trials are still needed to validate PMC for adoption into a standard clinical practice.

Emerging local ablation techniques

Local ablation technologies for hepatic malignancy have developed rapidly in the past decade, with advances in several percutaneous or externally delivered treatment methods including radiofrequency ablation, microwave ablation, laser ablation, and high-intensity focused ultrasound. Research has focused on increasing the size of the ablation zone and minimizing heat-sink effects. More recent developments include improvements in treatment planning and navigation with integration of several imaging modalities, as well as automated delivery of the ablation through robotics. These improvements will allow increased consistency in treatment delivery and will facilitate translation to the community setting. Combination therapies with multimodality guidance are on the cutting edge of image-guided, minimally invasive cancer therapies. Local ablation is being combined with regional therapies, such as arterial chemoembolization and local activation of systemically administered drugs, with promising results. Potential combinations with local ablation also include external radiation therapy and antitumor immune modulation. Image-guided oncology is emerging as an important part of the interventional radiology practice, thanks in part to the innovation and imaging background that lies at the roots of our discipline.

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.

Dielectric characterization of PCL-based thermoplastic materials for microwave diagnostic and therapeutic applications

We propose the use of a polycaprolactone (PCL)-based thermoplastic mesh as a tissue-immobilization interface for microwave imaging and microwave hyperthermia treatment. An investigation of the dielectric properties of two PCL-based thermoplastic materials in the frequency range of 0.5-3.5 GHz is presented. The frequency-dependent dielectric constant and effective conductivity of the PCL-based thermoplastics are characterized using measurements of microstrip transmission lines fabricated on substrates comprised of the thermoplastic meshes. We also examine the impact of the presence of a PCL-based thermoplastic mesh on microwave breast imaging. We use a numerical test bed comprised of a previously reported 3-D anatomically realistic breast phantom and a multi-frequency microwave inverse scattering algorithm. We demonstrate that the PCL-based thermoplastic material and the assumed biocompatible medium of vegetable oil are sufficiently well matched such that the PCL layer may be neglected by the imaging solution without sacrificing imaging quality. Our results suggest that PCL-based thermoplastics are promising materials as tissue immobilization structures for microwave diagnostic and therapeutic applications.

Minimally-invasive thermal ablation of early-stage breast cancer: a systemic review

BACKGROUND

Minimally-invasive thermal ablation techniques provide an effective approach for local destruction of solid tumor. A novel application is the use for treatment of early-stage breast carcinoma.

METHODS

A broad search was conducted in Pubmed, Embase and the Cochrane databases between January 1990 and December 2009. Clinical results of the relevant articles were collected and analyzed.

RESULTS

The analyzed studies were almost all feasibility or pilot studies using different energy sources, patients, tumor characteristics and ablation settings. They were conducted in research settings for the assessment of technical safety and feasibility, and none of those was used alone in clinical practice. Despite many methodological differences, complete tumor ablation could be achieved in 76-100% of breast cancer patients treated with radiofrequency ablation, 13-76% in laser ablation, 0-8% in microwave ablation, 36-83% in cryoablation, and 20-100% in high-intensity focused ultrasound ablation.

CONCLUSION

Minimally-invasive thermal ablation is a promising new tool for local destruction of small carcinomas of the breast. Large randomized control studies are required to assess the long-term advantages of minimally-invasive thermal ablation techniques compared to the current breast conserving therapies.

3D computational study of non-invasive patient-specific microwave hyperthermia treatment of breast cancer

Non-invasive microwave hyperthermia treatment of breast cancer is investigated using three-dimensional (3D) numerical breast phantoms with anatomical and dielectric-properties realism. 3D electromagnetic and thermal finite-difference time-domain simulations are used to evaluate the focusing and selective heating efficacy in four numerical breast phantoms with different breast tissue densities. Beamforming is used to design and focus the signals transmitted by an antenna array into the breast. We investigate the use of propagation models of varying fidelity and complexity in the design of the transmitted signals. An ideal propagation model that is exactly matched to the actual patient's breast is used to establish a best-performance baseline. Simpler patient-specific propagation models based on a homogeneous breast interior are also explored to evaluate the robustness of beamforming in practical clinical settings in which an ideal propagation model is not available. We also investigate the performance of the beamformer as a function of operating frequency and compare single-frequency and multiple-frequency focusing strategies. Our study suggests that beamforming is a robust method of non-invasively focusing microwave energy at a tumor site in breasts of varying volume and breast tissue density.

Non-invasive tissue temperature measurements based on quantitative diffuse optical spectroscopy (DOS) of water

We describe the development of a non-invasive method for quantitative tissue temperature measurements using Broadband diffuse optical spectroscopy (DOS). Our approach is based on well-characterized opposing shifts in near-infrared (NIR) water absorption spectra that appear with temperature and macromolecular binding state. Unlike conventional reflectance methods, DOS is used to generate scattering-corrected tissue water absorption spectra. This allows us to separate the macromolecular bound water contribution from the thermally induced spectral shift using the temperature isosbestic point at 996 nm. The method was validated in intralipid tissue phantoms by correlating DOS with thermistor measurements (R=0.96) with a difference of 1.1+/-0.91 degrees C over a range of 28-48 degrees C. Once validated, thermal and hemodynamic (i.e. oxy- and deoxy-hemoglobin concentration) changes were measured simultaneously and continuously in human subjects (forearm) during mild cold stress. DOS-measured arm temperatures were consistent with previously reported invasive deep tissue temperature studies. These results suggest that DOS can be used for non-invasive, co-registered measurements of absolute temperature and hemoglobin parameters in thick tissues, a potentially important approach for optimizing thermal diagnostics and therapeutics.

Focused microwave thermotherapy for preoperative treatment of invasive breast cancer: a review of clinical studies

BACKGROUND

Preoperative focused microwave thermotherapy (FMT) is a promising method for targeted treatment of breast cancer cells. Results of four multi-institutional clinical studies of preoperative FMT for treating invasive carcinomas in the intact breast are reviewed.

METHODS

Externally applied wide-field adaptive phased-array FMT has been investigated both as a preoperative heat-alone ablation treatment and as a combination treatment with preoperative anthracycline-based chemotherapy for breast tumors ranging in ultrasound-measured size from 0.8 to 7.8 cm.

RESULTS

In phase I, eight of ten (80%) patients receiving a single low dose of FMT prior to receiving mastectomy had a partial tumor response quantified by either ultrasound measurements of tumor volume reduction or by pathologic cell kill. In phase II, the FMT thermal dose was increased to establish a threshold dose to induce 100% pathologic tumor cell kill for invasive carcinomas prior to breast-conserving surgery (BCS). In a randomized study for patients with early-stage invasive breast cancer, of those patients receiving preoperative FMT at ablative temperatures, 0 of 34 (0%) patients had positive tumor margins, whereas positive margins occurred in 4 of 41 (9.8%) of patients receiving BCS alone (P = 0.13). In a randomized study for patients with large tumors, based on ultrasound measurements the median tumor volume reduction was 88.4% (n = 14) for patients receiving FMT and neoadjuvant chemotherapy, compared with 58.8% (n = 10) reduction in the neoadjuvant chemotherapy-alone arm (P = 0.048).

CONCLUSIONS

Wide-field adaptive phased-array FMT can be safely administered in a preoperative setting, and data from randomized studies suggest both a reduction in positive tumor margins as a heat-alone treatment for early-stage breast cancer and a reduction in tumor volume when used in combination with anthracycline-based chemotherapy for patients with large breast cancer tumors. Larger randomized studies are required to verify these conclusions.