Image-guided surgery of small breast cancers

Phase 2 Open-Label Trial Investigating Percutaneous Laser Ablation for Treatment of Early-Stage Breast Cancer: MRI, Pathology, and Outcome Correlations

Background

An institutional review board-approved, multicenter clinical trial was designed to determine the efficacy and outcome of percutaneous laser ablation (PLA) in the treatment of invasive ductal breast carcinoma (IDC). Post-ablation magnetic resonance imaging (MRI) was compared with surgical pathology in evaluation of residual post-ablation IDC and ductal carcinoma in situ.

Methods

Patients with a single focus of IDC 20 mm or smaller by pre-ablation MRI were treated with PLA. The patients underwent a 28-day post-ablation MRI, followed by surgical resection. Cell viability criteria were applied to pre- and post-ablation pathology specimens, which evaluated hematoxylin–eosin (H&E), cytokeratin (CK) 8/18, estrogen receptor, and Ki67 staining patterns.

Results

In this study, 61 patients were reported as the intention-to-treat cohort for determination of PLA efficacy. Of these 61 patients, 51 (84%) had complete tumor ablation confirmed by pathology analysis. One subject’s MRI imaging was not performed per protocol, which left 60 subjects evaluable for MRI pathology correlation. Five patients (8.3%) had residual IDC shown by both MRI and pathology. Post-ablation discordance was noted between MRI and pathology, with four patients (6.7%) false-positive and four patients (6.7%) false-negative. The negative predictive value (NPV) of MRI for all the patients was 92.2% (95% confidence interval [CI], 71.9–91.9%). Of the 47 patients (97.9%) with tumors 15 mm or smaller, 46 were completely ablated, with an MRI NPV of 97.7% (95% CI, 86.2–99.9%).

Conclusions

Percutaneous laser ablation is a potential alternative to surgery for treatment of early-stage IDC. Strong correlations exist between post-ablation MRI and pathologic alterations in CK8/18, ER, and Ki67 staining.

Cryosurgery for breast fibroadenomas

Fibroadenomas are the most common benign tumors in the breast of women during their second and third decades of life, and account for 30% and 50% of all breast biopsies, and these rates rise to about 75% for biopsies in women under the age of 20. The tumors commonly present a painless, palpable, solid, rubbery, well-circumscribed, and movable mass with no associated risk of carcinoma. With the vast array of image-guided biopsy devices, fibroadenomas can be easily sampled and diagnosed. With use of ultrasound-guided cryoablation for breast fibroadenomas, there is little or no pain, targeted lesions are reduced in size or eliminated, scarring is minimal, cosmesis is outstanding, and patient satisfaction is excellent. Cryosurgery should be a preferred option for those patients desiring definitive therapy for their fibroadenomas without surgical intervention.

Model-updated image-guided liver surgery: preliminary results using surface characterization

The current protocol for image guidance in open abdominal liver tumor removal surgeries involves a rigid registration between the patient's operating room space and the pre-operative diagnostic image-space. Systematic studies have shown that the liver can deform up to 2 cm during surgeries in a non-rigid fashion thereby compromising the accuracy of these surgical navigation systems. Compensating for intra-operative deformations using mathematical models has shown promising results. In this work, we follow up the initial rigid registration with a computational approach that is geared towards minimizing the residual closest point distances between the un-deformed pre-operative surface and the rigidly registered intra-operative surface. We also use a surface Laplacian equation based filter that generates a realistic deformation field. Preliminary validation of the proposed computational framework was performed using phantom experiments and clinical trials. The proposed framework improved the rigid registration errors for the phantom experiments on average by 43%, and 74% using partial and full surface data, respectively. With respect to clinical data, it improved the closest point residual error associated with rigid registration by 54% on average for the clinical cases. These results are highly encouraging and suggest that computational models can be used to increase the accuracy of image-guided open abdominal liver tumor removal surgeries.

Minimally invasive approaches for diagnosis and treatment of early-stage breast cancer

Breast cancer management has been evolving toward minimally invasive approaches. Image-guided percutaneous biopsy techniques provide accurate histologic diagnosis without the need for surgical biopsy. Breast conservation therapy has become the treatment standard for early-stage breast cancer. Sentinel lymph node biopsy is a new procedure that can predict axillary lymph node status without the need of axillary lymph node dissection. The next challenge is to treat primary tumors without surgery. For this purpose, several new minimally invasive procedures, including radiofrequency ablation, interstitial laser ablation, focused ultrasound ablation, and cryotherapy, are currently under development and may offer effective tumor management and provide treatment options that are psychologically and cosmetically more acceptable to the patients than are traditional surgical therapies. In this review, we give an overview of minimally invasive approaches for the diagnostic and therapeutic management of early-stage breast cancer.

Percutaneous Excisional Biopsy of Palpable Breast Masses under Ultrasound Visualization

A palpable breast mass is a common reason for surgical consultation. Our goal was to determine whether ultrasound-guided vacuum-assisted core biopsy (US-VACB) is safe and effective in completely removing presumed benign palpable breast masses. We conducted a cohort study of 201 consecutive patients with presumed benign palpable masses who underwent removal with US-VACB. The main outcome measured was the successful removal of palpable masses. Palpable masses were successfully removed with US-VACB in 99% of cases; 2% were cancer and 7.5% were atypical ductal hyperplasia or phyllodes tumor. Two clinical recurrences representing a seroma were seen on follow-up. US-VACB is safe and effective in the initial diagnosis and management of presumed benign palpable breast masses. It provides the benefits of percutaneous biopsy and the palpable abnormality no longer remains.

MR-Guided Interventions of the Breast

Techniques and instrumentation are now widely available that enable interventional MR-guided preoperative needle localization and lesion marking. Minimally invasive MR-guided core biopsy techniques have been demonstrated but remain limited for small lesions and will be facilitated by the development of biopsy instruments that can be directly visualized using MR imaging. MR-guided tumor ablation is beginning to be evaluated in a few centers. It holds promise as new treatment modality in the continuing trend toward greater breast conservation in the local therapy of breast cancer. Further studies are needed to document the ability of MR-guided ablation to control the margins of a tumor as effectively as surgery. Patients with an extensive in situ intra-ductal component may pose a significant hurdle because the extent of ductal carcinoma in situ maybe underestimated on breast MR images. Ultimately, the success of MR-guided thermal ablation depends on the ability of MR imaging to map the extent of heating during the procedure so that the procedure can be performed to achieve complete control of the tumor margins. It is unfortunate that the conventional method for MR thermometry--the proton resonance frequency shift method--does not work in fat or in voxels with a mix of fat and glandular tissue and, hence, has limited applicability in the breast. Other methods, including measurement of T1 and T2, are being investigated as alternatives.

Ablative therapies for the treatment of malignant diseases of the breast

BACKGROUND

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

DATA SOURCES

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

CONCLUSIONS

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

Nonsurgical ablation of primary breast cancer

The potential for these therapies is overwhelming when one considers that as many as 90,000 patients may be candidates annually in the United States. The ideal therapy should be safe, as painless as possible, accessible, and effective in reducing local recurrence. Because of the novelty of these techniques, no therapy has met all of these goals. Even if these ideals are attained, questions remain about how to follow these patients with regard to frequency and imaging modality for local recurrence. As these technologies are refined, and they mature; it is conceivable that the future treatment of breast cancer may be less morbid than the open breast biopsies now being used for just the diagnosis of the disease.

Cryotherapy for breast fibroadenomas

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

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

BACKGROUND

Tumor ablation as a means of treating breast cancer is being investigated. Microwave energy is promising because it can preferentially heat high-water-content breast carcinomas, compared to adipose and glandular tissues.

METHODS

This is a prospective, multicenter, nonrandomized dose-escalation study of microwave treatment. Thermal dose was measured as (1) thermal equivalent minutes (cumulative equivalent minutes; CEM) of treatment relative to a temperature of 43 degrees C and (2) peak tumor temperature. Microwaves were guided by an antenna-temperature sensor placed percutaneously into the tumor. Outcomes measured were pathologic response (tumor necrosis) side effects.

RESULTS

Twenty-five patients (mean age, 57 years) were enrolled. The mean tumor diameter was 1.8 cm. Tumoricidal temperatures (>43 degrees C) were reached in 23 patients (92%). Tumor size was unchanged after thermotherapy (P = not significant). Pathologic necrosis was achieved in 17 (68%) patients. Complete necrosis of the invasive component was achieved in two patients. One hundred forty CEM is predictive of a 50% tumor response, and 210 CEM is predictive of a 100% tumor response (P =.003). Univariate linear regression predicts that peak tumor temperatures of 47.4 degrees C and 49.7 degrees C cause a 50% tumor response and a 100% tumor response, respectively.

CONCLUSIONS

Thermotherapy causes tumor necrosis and can be performed safely with minimal morbidity. The degree of tumor necrosis is a function of the thermal dose. Future studies will evaluate the impact of high doses of thermotherapy on margin status and complete tumor ablation.

Office-based ultrasound-guided cryoablation of breast fibroadenomas

BACKGROUND

Fibroadenomas commonly found by palpation and routine mammography account for approximately 20% of open surgical breast biopsies. Alternatives to open surgery include tumor removal using an automated coring device and tumor ablation using heating or cooling elements. We report our initial experience with cryoablation of biopsy-proven benign fibroadenomas.

METHODS

A table-top cryoablation system employing a 2.4-mm cryoprobe was used to treat biopsy-proven benign fibroadenomas up to 4 cm in maximum diameter in a prospective nonrandomized fashion. The cryoprobe was placed under ultrasound guidance. Using a treatment algorithm based on fibroadenoma size, all tumors were subjected to two freeze cycles with an interposing thaw. Skin appearance and temperature, probe temperature, iceball size, and patient comfort were closely monitored during the procedure. Follow-up examinations including ultrasonography and photographs were scheduled for up to 12 months postablation.

RESULTS

Fifty patients with 57 core biopsy-proven benign fibroadenomas were treated. Seven early cases were treated in an ambulatory surgery center setting. The remaining procedures were completely office-based using only local anesthetic. Tumor diameter varied from 7 mm to 42 mm (mean 21 mm). The iceball engulfed the target lesion in each case. Transient postoperative side effects were local swelling and ecchymosis. Postoperative discomfort rarely required medication beyond acetaminophen or ibuprofen. Lesions showed progressive shrinkage and disappearance over 3 to 12 months. No skin injury was noted and appearance remained excellent. Patient satisfaction was excellent.

CONCLUSIONS

With office-based use of ultrasound-guided cryoablation for fibroadenomas there was little or no pain, target lesions were reduced in size or eliminated, scarring was minimal, cosmesis outstanding, and patient satisfaction was excellent. Cryoablation offers a useful office-based alternative to surgical excision of benign fibroadenomas.