Minimally invasive ablative therapies for invasive breast carcinomas: an overview of current literature

Validation of a drift-corrected 3D MR temperature imaging sequence for breast MR-guided focused ultrasound treatments

Real-time temperature monitoring is critical to the success of thermally ablative therapies. This work validates a 3D thermometry sequence with k-space field drift correction designed for use in magnetic resonance-guided focused ultrasound treatments for breast cancer. Fiberoptic probes were embedded in tissue-mimicking phantoms, and temperature change measurements from the probes were compared with the magnetic resonance temperature imaging measurements following heating with focused ultrasound. Precision and accuracy of measurements were also evaluated in free-breathing healthy volunteers (N = 3) under a non-heating condition. MR temperature measurements agreed closely with those of fiberoptic probes, with a 95% confidence interval of measurement difference from -2.0 °C to 1.4 °C. Field drift-corrected measurements in vivo had a precision of 1.1 ± 0.7 °C and were accurate within 1.3 ± 0.9 °C across the three volunteers. The field drift correction method improved precision and accuracy by an average of 46 and 42%, respectively, when compared to the uncorrected data. This temperature imaging sequence can provide accurate measurements of temperature change in aqueous tissues in the breast and support the use of this sequence in clinical investigations of focused ultrasound treatments for breast cancer.

Laser interstitial thermotherapy (LITT) for breast cancer: dosimetry optimization and numerical simulation

Surgical treatment is standard for the treatment of small breast cancers. Due to the pain and esthetic sequelae that can follow surgery, minimally invasive treatments are under investigation. Our aim was to conduct a dosimetry study of laser interstitial thermotherapy. Turkey tissue was used as an ex vivo model, and mammary glands from ewes were used as in vivo models. We used two different wavelength lasers (805 nm and 980 nm). Two types of fiber from two different manufacturers were used: bare fibers with a diameter of 600 μm and diffusing fiber. The diffusing fibers were 5 mm and 10 mm in length. We also used a computerized model to predict thermal damage and to correlate with the ex vivo and in vivo procedures using a constant and variable coefficient. The mathematical model was based on the finite element method for solving light distribution, bio-heat, and thermal damage equations. Based on our ex vivo and in vivo experiments, we found that the optimal configuration for this treatment was the use of the 980-nm laser at 4 W with bare fibers for a minimum treatment time of 150 s. We also developed a predictive mathematical model that showed good predictability of necrosis in line with the experimental data. Laser treatment is a promising therapy for small breast lesions. However, further development of treatment guidance is necessary to support its use in clinical practice.

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.

Laser interstitial thermotherapy application for breast surgery: Current situation and new trends

While breast specialists debate on therapeutic de-escalation in breast cancer, the treatment of benign lesions is also discussed in relation to new percutaneous ablation techniques. The purpose of these innovations is to minimize potential morbidity. Laser Interstitial ThermoTherapy (LITT) is an option for the ablation of targeted nodules. This review evaluated the scientific publications investigating the LITT approach in malignant and benign breast disease. Three preclinical studies and eight clinical studies (2 studies including fibroadenomas and 6 studies including breast cancers) were reviewed. Although the feasibility and safety of LITT have been confirmed in a phase I trial, heterogeneous inclusion criteria and methods seem to be the main reason for LITT not being yet an extensively used treatment option. In conclusion, further development is necessary before this technique can be used in daily practice.

Damage effect of high-intensity focused ultrasound on breast cancer tissues and their vascularities

BACKGROUND

High-intensity focused ultrasound (HIFU) is a noninvasive therapy that makes entire coagulative necrosis of a tumor in deep tissue through the intact skin. There are many reports about the HIFU's efficacy in the treatment of patients with breast cancer, but randomized clinical trials are rare which emphasize on the systematic assessment of histological changes in the ablated tumor vascularities, while clinical trials utilizing bevacizumab and other anti-angiogenic drugs in breast cancer have not demonstrated overall survival benefit. The purpose of this study is to evaluate the damage effect of HIFU on breast cancer tissues and their vascularities.

METHODS

Randomized clinical trials and the modality of treat-and-resect protocols were adopted. The treated outcome of all patients was followed up in this study. The target lesions of 25 breast cancer patients treated by HIFU were observed after autopsy. One slide was used for hematoxylin-eosin (HE) staining, one slide was used for elastic fiber staining by Victoria blue and Ponceau's histochemical staining, and one slide was used for vascular endothelial cell immunohistochemical staining with biotinylated-ulex europaeus agglutinin I (UEAI); all three slides were observed under an optical microscopic. One additional slide was systematically observed by electron microscopy.

RESULTS

The average follow-up time was 12 months; no local recurrence or a distant metastatic lesion was detected among treated patients. Histological examination of the HE slides indicated that HIFU caused coagulative necrosis in the tumor tissues and their vascularities: all feeder vessels less than 2 mm in diameter in the insonated tumor were occluded, the vascular elasticity provided by fibrin was lost, the cells were disordered and delaminated, and UEAI staining of the target lesions was negative. Immediately after HIFU irradiation, the tumor capillary ultrastructure was destroyed, the capillary endothelium was disintegrated, the peritubular cells were cavitated, and the plasma membrane was incomplete.

CONCLUSIONS

HIFU ablation can destroy all proliferating tumor cells and their growing vascularities simultaneously; this may break interdependent vicious cycle of tumor angiogenesis and neoplastic cell growth that results in infinite proliferation. While it cannot cause tumor resistance to HIFU ablation, it may be a new anti-angiogenic strategy that needs further clinical observation and exploration. Furthermore, the treatment indications of HIFU ablation were reviewed and discussed in this manuscript.

Effect of phase difference in multi-antenna microwave thermal ablation for breast cancer treatment

It was realized that cancer in breast is one of the most health hazards threatening women around the world for many years. Thermal ablation by using microwave energy is another alternative surgical maneuver due to its minimally invasive therapeutic technique. In this research, we investigate an effect of phase difference between three adjacent opened-slot coaxial probes in a multiple antenna alignment of microwave thermal ablation system for breast cancer treatment. FEM by using COMSOL is an implementation tools to simulate for 0, 45, 90, 135 and 180 degree of phase difference. 3D Simulation results show that temperature distribution pattern, destructive volume and SAR in breast tissue are affected from those phase-shift utilization in multi-antenna system significantly.

Magnetic Hyperthermia Ablation of Tumors Using Injectable Fe₃O₄/Calcium Phosphate Cement

In this work, we have developed an injectable and biodegradable material using CPC containing Fe3O4 nanoparticles for minimally invasive and efficiently magnetic hyperthermia ablation of tumors. When exposed to an alternating magnetic field, the MCPC could quickly generate heat. The temperature of PBS and the excised bovine liver increased with the MCPC weight, iron content, and time. The ablated liver tissue volume for 0.36 g of 10% MCPC was 0.2 ± 0.03, 1.01 ± 0.07, and 1.96 ± 0.19 cm(3), respectively, at the time point of 60, 180, and 300 s. In our in vivo experiment, the MCPC could be directly injected into the center of the tumors under the guidance of ultrasound imaging. The formed MCPC was well-restricted within the tumor tissues without leakage, and the tumors were completely ablated by 0.36 g of 10% injectable MCPC after 180 s of induction heating.

Impact of preoperative evaluation of tumour grade by core needle biopsy on clinical risk assessment and patient selection for adjuvant systemic treatment in breast cancer

BACKGROUND

Histological characteristics are important when making a decision on adjuvant systemic treatment in breast cancer. Preoperative assessments of core needle biopsy (CNB) specimens are becoming increasingly relevant as novel minimally invasive ablative techniques are introduced, because a surgical specimen is no longer obtained with these methods. The clinical impact of potential underestimation of tumour grade on preoperative CNB on clinical decision-making was evaluated.

METHODS

Histological tumour grade was reassessed on CNB and resection specimens from consecutive invasive ductal carcinomas diagnosed between 2010 and 2013. For each patient, the indication for systemic therapy was assessed, based on either CNB or surgical excision, in combination with clinical characteristics and imaging findings. The clinical impact of discordance between tumour grade on CNB versus the resection specimen was assessed.

RESULTS

The analysis included 213 invasive ductal carcinomas in 199 patients. Discordance in tumour grade between CNB and the resection specimen was observed in 64 (30.0 per cent) of 213 tumours (κ = 0.53, 95 per cent c.i. 0.43 to 0.63). A decision on adjuvant treatment based on CNB would have resulted in overtreatment in seven (3.5 per cent) and undertreatment in three (1.5 per cent) of 199 patients. In the undertreated patients, incorrect omission of adjuvant systemic treatment would have increased the predicted 10-year mortality rate by 2.6-5.2 per cent and 10-year recurrence rate by 8.2-15.3 per cent based on the online risk assessment tool Adjuvant!

CONCLUSION

The substantial discordance in tumour grading between CNB and resection specimens from breast cancer affects the indication for adjuvant therapy in only a small minority of patients with invasive ductal carcinoma. Assessment of tumour grade by CNB is feasible and accurate for the planning of postoperative treatment.

Subclinical Breast Cancer: Minimally Invasive Approaches. Our Experience with Percutaneous Radiofrequency Ablation vs. Cryotherapy

BACKGROUND

The aim of this study was to compare the efficacy of radiofrequency ablation vs. cryoablation in the treatment of early breast cancer.

PATIENTS AND METHODS

80 women (mean age 73 ± 5 years) with early breast cancer were retrospectively evaluated. 40 patients underwent cryoablation and 40 patients underwent radiofrequency ablation, both with sentinel lymph node excision. Tumor volume and histopatological data were compared by means of postprocedural 3.0-T magnetic resonance imaging (MRI). 30-45 days after the percutaneous ablation, all patients underwent surgical resection of the tumor. The mean follow-up was 18 months without any local recurrences.

RESULTS

Both techniques allow good correlation with histopathological data. In 75 patients (93.8%) we observed complete necrosis; in 5 cases there was residual disease in the postprocedural MRI and postoperative histological examination. There was a good correlation between MRI volume and histologic samples. Cosmetic results were good in all patients but 2.

CONCLUSION

Both percutaneous radiofrequency ablation and cryotherapy are minimally invasive techniques with a good clinical and cosmetic outcome in selected cases. MRI examination is an ideal method to assess breast neoplasms in terms of quality and quantity as well as residual tumor extent after percutaneous ablation. Cryotherapy is the preferred method because of the analgesic effect of freezing with better patients compliance.

Ultrasound-guided characterization of interstitial ablated tissue using RF time series: feasibility study

This paper presents the results of a feasibility study to demonstrate the application of ultrasound RF time series imaging to accurately differentiate ablated and nonablated tissue. For 12 ex vivo and two in situ tissue samples, RF ultrasound signals are acquired prior to, and following, high-intensity ultrasound ablation. Spatial and temporal features of these signals are used to characterize ablated and nonablated tissue in a supervised-learning framework. In cross-validation evaluation, a subset of four features extracted from RF time series produce a classification accuracy of 84.5%, an area under ROC curve of 0.91 for ex vivo data, and an accuracy of 85% for in situ data. Ultrasound RF time series is a promising approach for characterizing ablated tissue.

Analysis by MRI of residual tumor after radiofrequency ablation for early stage breast cancer

OBJECTIVE

The objective of our study was to evaluate the effectiveness of MRI in the detection of possible residual lesions after radiofrequency ablation (RFA) in the treatment of breast cancer.

SUBJECTS AND METHODS

We prospectively evaluated 14 patients who had undergone ultrasound-guided core biopsies diagnostic of invasive ductal carcinoma (IDC; range of diameters, 1.0-3.0 cm) and then ultrasound-guided percutaneous RFA with sentinel node biopsy as the primary treatment. Breast MRI was performed 1 week before RFA to evaluate tumor extension and again 3 weeks after RFA to verify the presence of possible residual lesions. Conventional surgical resection of the tumors was performed 1 week after RFA. The MRI findings were compared with histopathologic analyses to confirm the presence or absence of residual tumor.

RESULTS

There was no residual enhancement in seven lesions on the postablation breast MRI scans. These findings were confirmed by negative histopathologic findings in the surgical specimens. The MRI scans of five patients showed small areas of irregular enhancement that corresponded to residual lesions. In the two remaining patients, we observed enhancement of almost the entire lesion, indicating that RFA had failed.

CONCLUSION

Breast MRI is effective in detecting residual lesions after RFA in patients with IDC.

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.

MRI-guided ablation of breast cancer: where do we stand today?

The treatment of patients with localized breast cancer has changed considerably over the past few decades. The next challenge is to use image-guided minimally invasive tumor ablation techniques. The fact that MRI is the most accurate imaging modality for visualization and delineation of breast tumor margins in three dimensions and provides MRI-based temperature mapping, makes it particularly applicable for monitoring during minimally invasive ablation techniques. The overall result of the studies performed on MRI-guided minimally invasive tumor ablation studies are varying, with reported total tumor ablation rates ranging between 20% and 100%. Strict selection of patients, consensus on the treatment zone margin and optimization of MR-imaging, should make MRI-guided breast cancer tumor ablation a useful tool in clinical practice.

Microwave ablation compared with radiofrequency ablation for breast tissue in an ex vivo bovine udder model

PURPOSE

To compare the effectiveness of microwave (MW) ablation with radiofrequency (RF) ablation for treating breast tissue in a nonperfused ex vivo model of healthy bovine udder tissue.

MATERIALS AND METHODS

MW ablations were performed at power outputs of 25W, 35W, and 45W using a 915-MHz frequency generator and a 2-cm active tip antenna. RF ablations were performed with a bipolar RF system with 2- and 3-cm active tip electrodes. Tissue temperatures were continuously monitored during ablation.

RESULTS

The mean short-axis diameters of the coagulation zones were 1.34 ± 0.14, 1.45 ± 0.13, and 1.74 ± 0.11 cm for MW ablation at outputs of 25W, 35W, and 45W. For RF ablation, the corresponding values were 1.16 ± 0.09 and 1.26 ± 0.14 cm with electrodes having 2- and 3-cm active tips, respectively. The mean coagulation volumes were 2.27 ± 0.65, 2.85 ± 0.72, and 4.45 ± 0.47 cm(3) for MW ablation at outputs of 25W, 35W, and 45W and 1.18 ± 0.30 and 2.29 ± 0.55 cm(3) got RF ablation with 2- and 3-cm electrodes, respectively. MW ablations at 35W and 45W achieved significantly longer short-axis diameters than RF ablations (P < 0.05). The highest tissue temperature was achieved with MW ablation at 45W (P < 0.05). On histological examination, the extent of the ablation zone in MW ablations was less affected by tissue heterogeneity than that in RF ablations.

CONCLUSION

MW ablation appears to be advantageous with respect to the volume of ablation and the shape of the margin of necrosis compared with RF ablation in an ex vivo bovine udder.

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.

Ultrasound-guided core-needle biopsy of breast lesions

Objective

To review the role of ultrasound-guided core-needle biopsy (CNB) in the management of breast lesions.

Methods

Review of the most relevant literature on this topic.

Results

This technique shows a high sensitivity value of about 97.5% and it offers many advantages over other imaging techniques to guide a biopsy: non-ionising radiation, low cost, full control of the needle in real time, accessibility in difficult locations, multidirectional punctures and excellent comfort for patients and radiologists. All of these advantages have made this technique the most widespread used to perform a biopsy for a suspicious breast lesion. The most important limitation is the failure to perform a biopsy for lesions that are not seen on ultrasound. An adequate radiological–pathological correlation is necessary to minimise the false-negative results.

Conclusion

Ultrasound-guided CNB has proven to be a reliable technique for performing a biopsy for breast lesions that can be clearly seen on ultrasound.

Combination radiofrequency ablation and intravenous radiolabeled liposomal Doxorubicin: imaging and quantification of increased drug delivery to tumors

PURPOSE

To identify, with noninvasive imaging, the zone of radiopharmaceutical uptake after combination therapy with radiofrequency (RF) ablation and intravenous administration of technetium 99m ((99m)Tc) liposomal doxorubicin in a small-animal tumor model, and to quantify and correlate the uptake by using imaging and tissue counting of intratumoral doxorubicin accumulation.

MATERIALS AND METHODS

This study was approved by the animal care committee. Two phases of animal experiments were performed. In the first experiment, a single human head-and-neck squamous cell carcinoma tumor was grown in each of 10 male nude rats. Seven of these animals were treated with intravenous (99m)Tc-liposomal doxorubicin followed by RF tumor ablation at a mean temperature of 70 degrees C + or - 2 for 5 minutes, and three were treated with intravenous (99m)Tc-liposomal doxorubicin only. Combination single photon emission computed tomography-computed tomography (SPECT/CT) was performed at 15 minutes, 4 hours, and 20 hours after therapy. In the second experiment, two tumors each were grown in 11 rats, but only one of the tumors was ablated after intravenous administration of (99m)Tc-liposomal doxorubicin. SPECT/CT and planar scintigraphy were performed at the same posttreatment intervals applied in the first experiment, with additional planar imaging performed at 44 hours. After imaging, tissue counting in the excised tumors was performed. Radiotracer uptake, as determined with imaging and tissue counting, was quantified and compared. In a subset of three animals, intratumoral doxorubicin accumulation was determined with fluorimetry and correlated with the imaging and tissue-counting data.

RESULTS

At both SPECT/CT and planar scintigraphy, increased uptake of (99m)Tc-liposomal doxorubicin was visibly apparent in the ablated tumors. Results of quantitative analysis with both imaging and tissue counting confirmed significantly greater uptake in the RF ablation-treated tumors (P < .001). Intratumoral doxorubicin accumulation correlated closely with imaging (r = 0.9185-0.9871) and tissue-counting (r = 0.995) results.

CONCLUSION

Study results show that increased delivery of intravenous liposomal doxorubicin to tumors combined with RF ablation can be depicted and quantified with noninvasive imaging.

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.

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.

Radiofrequency ablation of breast cancer: a comparative study of two needle designs

BACKGROUND

Radiofrequency ablation (RFA) is an emerging minimally invasive technique for breast cancer treatment. There are two different needle designs. One is to deploy a series of arrays to allow an even distribution of heat within the tumor. A new design is a straight needle with continuous infusion of cold saline to prevent charring and ensure continuous heat delivery. We report the first comparative study using two different needles for ablation of breast cancer.

METHODS

Chinese patients with breast cancer less than 2 cm were prospectively recruited. Multifocal tumor was excluded. RFA was performed under general anesthesia following sentinel node biopsy. Sequential allocation was used. In the first group, tumor was ablated by using the LeVeen needle. Cool-tip needle was used in the subsequent group. The tumor was then resected. Tumor viability was assessed by nicotinamide adenine dinucleotide-diaphorase (NADH) staining. Complete ablation rate was compared. Evidence of thermal damage to the skin was also assessed.

RESULTS

Twenty patients were recruited. Mean tumor size was 14 mm. Complete ablation rate was the same (90% versus 89% for the Cool-tip and the LeVeen, respectively). Cool-tip has a shorter ablation time when compared with LeVeen (12 versus 28 min), and the Cool-tip needle was found to be easier to insert. There was no visible skin burn after RFA.

CONCLUSIONS

Cool-tip and LeVeen systems had the same efficacy in ablation of breast cancer, but Cool-tip was easier to insert and had a shorter ablation time.

In vivo feasibility of real-time monitoring of focused ultrasound surgery (FUS) using harmonic motion imaging (HMI)

In this study, the Harmonic Motion Imaging for Focused Ultrasound (HMIFU) technique is applied to monitor changes in mechanical properties of tissues during thermal therapy in a transgenic breast cancer mouse model in vivo. An HMIFU system, composed of a 4.5-MHz focused ultrasound (FUS) and a 3.3-MHz phased-array imaging transducer, was mechanically moved to image and ablate the entire tumor. The FUS transducer was driven by an amplitude-modulated (AM) signal at 15 Hz. The acoustic intensity ( I(spta)) was equal to 1050 W/cm(2) at the focus. A digital low-pass filter was used to filter out the spectrum of the FUS beam and its harmonics prior to displacement estimation. The resulting axial displacement was estimated using 1-D cross-correlation on the acquired RF signals. Results from two mice with eight lesions formed in each mouse (16 lesions total) showed that the average peak-to-peak displacement amplitude before and after lesion formation was respectively equal to 17.34 +/- 1.34 microm and 10.98 +/- 1.82 microm ( p << 0.001). Cell death was also confirmed by hematoxylin and eosin histology. HMI displacement can be used to monitor the relative tissue stiffness changes in real time during heating so that the treatment procedure can be performed in a time-efficient manner. The HMIFU system may, therefore, constitute a cost-efficient and reliable alternative for real-time monitoring of thermal ablation.

Ultrasound-guided laser-induced thermal therapy for small palpable invasive breast carcinomas: a feasibility study

Background

The next step in breast-conserving surgery for small breast carcinomas could be local ablation. In this study, the feasibility of ultrasound-guided laser-induced thermal therapy (LITT) is evaluated.

Methods

Patients with large-core needle biopsy-proven invasive, palpable breast carcinoma (clinically ≤2 cm) underwent ultrasound-guided LITT, followed by surgical excision. Completeness of ablation was determined by both hematoxylin and eosin staining and nicotinamide adenosine diaphorase staining.

Results

Fourteen patients completed the treatment. The mean histological tumor size was 17 mm (range, 8–37 mm); 6 of 14 tumors were histologically larger than the clinical entry threshold of 2 cm. The power applied in all patients was 7 W, and the mean treatment time was 21.4 min (range, 15–30 min). In one patient, a skin burn occurred, and one patient had a localized pneumothorax that could be treated conservatively. In 7 (50%) of 14 patients, the tumor was completely ablated, as confirmed by nicotinamide adenosine diaphorase staining. In 11 cases, extensive in-situ carcinoma was present. In one case, the in-situ carcinoma was also completely ablated. A total of seven (88%) of eight tumors <2 cm in size were completely ablated versus one (17%) of six tumors that were ≥2 cm in size (P = .026).

Conclusions

Successful LITT of invasive breast cancer seems to be feasible when confined to small (<2 cm) nonlobular carcinomas without surrounding extensive in-situ component and angioinvasion. However, to implement LITT in a curative setting, improvements in imaging to more reliably preoperatively assess tumor size and monitoring of fiber tip placement and treatment affect are essential.

Thermal ablation of the goat mammary gland as a model for post-lumpectomy treatment of breast cancer: preliminary observations

BACKGROUND

Partial breast irradiation post-lumpectomy, with a balloon bearing a radioactive source in its center, is practiced as an alternative to whole breast irradiation in the treatment of breast cancer. The goal is to ablate residual malignant cells within 1 cm radius of the resected lumpectomy margin. We hypothesize that this goal may be achieved with a fluid-filled heated balloon.

METHODS

Nubian-cross goats were treated under general anesthesia. The two mammary glands were sequentially bisected and a non-inflated balloon with a heating element was placed in the center of the gland which was re-sutured. Two series of experiments were conducted. In the first 22 goats (44 glands), the balloon was inflated with 5% dextrose to a pressure of 150 mmHg and heated at 87 degrees C over selected time intervals of 1-24 minutes. In the second series (16 glands), the re-programmed device operated at 50-80 mmHg over selected time intervals of 5-20 minutes. The depth of necrosis was histologically determined after sacrificing the goats and excising the glands.

RESULTS

In the first series, glandular necrosis was noted to extend to a depth of 3.2-9.6 mm for the above heating cycles. Corresponding figures for the second series ranged from 4.7-8.6 mm for treatment times of one minute 'warm up' to 20 minutes of heating at 90 degrees C. The animals exhibited no systemic side effects post-treatment.

CONCLUSION

An experimental model describing a thermal technique causing necrosis of the goat mammary gland is described.

Radiofrequency thermal ablation of breast cancer local recurrence: a phase II clinical trial

BACKGROUND

The role of radiofrequency (RF) ablation to treat local recurrence of breast cancer is unknown.

METHODS

We conducted a two-stage phase II clinical trial. Eligible patients had a histologically confirmed noninflammatory and < or =3 cm ipsilateral breast tumor recurrence. The tumor site was identified by intraoperative sonography. A LeVeen needle electrode (RadioTherapeutics Corp, Mountain View, Calif) was inserted into a single site within the tumor and radiofrequency ablation was performed using a RF-2000 generator (RadioTherapeutics Corp). After completion of radiofrequency, a mastectomy was performed. Conventional staining and nicotinamide adenine dinucleotide-diaphorase (NADH-diaphorase) cell viability staining were performed.

RESULTS

During the first stage, procedures were uneventful. Conventional, cytokeratin, and NADH-diaphorase staining identified persistent viable tumor cells in the RF-ablated region in three patients. This phase II trial was stopped after completion of the first stage because of insufficient efficacy.

CONCLUSION

We demonstrate in this study that RF ablation is a potential technique to destroy local recurrence of breast tumors but the technique we tested in this phase II clinical trial had insufficient efficacy to recommend its use in routine.

Image-guided focused ultrasound ablation of breast cancer: current status, challenges, and future directions

Image-guided focussed ultrasound (FUS) ablation is a non-invasive procedure that has been used for treatment of benign or malignant breast tumours. Image-guidance during ablation is achieved either by using real-time ultrasound (US) or magnetic resonance imaging (MRI). The past decade phase I studies have proven MRI-guided and US-guided FUS ablation of breast cancer to be technically feasible and safe. We provide an overview of studies assessing the efficacy of FUS for breast tumour ablation as measured by percentages of complete tumour necrosis. Successful ablation ranged from 20% to 100%, depending on FUS system type, imaging technique, ablation protocol, and patient selection. Specific issues related to FUS ablation of breast cancer, such as increased treatment time for larger tumours, size of ablation margins, methods used for margin assessment and residual tumour detection after FUS ablation, and impact of FUS ablation on sentinel node procedure are presented. Finally, potential future applications of FUS for breast cancer treatment such as FUS-induced anti-tumour immune response, FUS-mediated gene transfer, and enhanced drug delivery are discussed. Currently, breast-conserving surgery remains the gold standard for breast cancer treatment.