Postlumpectomy Insertion of the MammoSite Brachytherapy Device Using the Scar Entry Technique: Initial Experience and Technical Considerations

Discrepancies in determining electron energy for lumpectomy boost treatment

The aim of this study was to compare lumpectomy cavity depth measurements obtained through ultrasound (U/S) and retrospective computed tomography (CT). Twenty-five patients with stage T1-2 invasive breast cancer formed the cohort of this study. Their U/S and CT measurements were converted into electron energy and compared. The mean U/S depth was 3.6 ± 1.3 cm, while the mean CT depth was 4.9 ± 1.9 cm; the listed error ranges are one standard deviation. Electron energies for treatment ranged from 6 MeV to 12 MeV based on the U/S determination. There was no significant correlation between cavity depths measured by U/S and CT (R²= 0.459, P < 0.002). Furthermore, only 20% of CT-based electron energy determinations matched the corresponding U/S determinations. This ratio increased to 40% when taking into account an upper limit based on the depth of organs at risk below the cavity. The study shows that there is a significant discrepancy between cavity depths determined by U/S and CT. It also supports the concept that post-lumpectomy radiotherapy boosts should be tailored according to the needs and comfort of individual practices and institutions.

Modeling study for optimization of skin dose for partial breast irradiation using Xoft Axxent electronic brachytherapy applicator

PURPOSE

Balloon brachytherapy with the MammoSite system (Hologic Inc., Bedford, MA) is a widely used approach for accelerated partial breast irradiation. Inherent to this approach, high skin doses can occur if the balloon to skin distance is small. This has been associated with late skin toxicity, particularly telangiectasia. The Xoft Axxent electronic brachytherapy balloon applicator (Xoft, Fremont, CA) is a novel device for accelerated partial breast irradiation. It is unique in that it uses an electronic 50-kV source. This source has a pronounced anisotropy with constriction of isodose distribution at the proximal end of the catheter. This anisotropy can be considered as an advantage to optimize skin dose when the cavity to skin distance is small. In this study, we simulated various balloon-insertion orientations to optimized skin surface dose.

METHODS

Breast phantoms were constructed of tissue-equivalent material. Xoft Axxent balloon catheters were inserted at a distance of 6mm from the surface. The catheter was placed at three different catheter to surface orientations: (1) perpendicular to the surface, (2) oblique to the surface (45 degrees), and (3) parallel to the surface. Three-dimensional treatment planning was then performed using Nucletron's Plato planning system (Nucletron, Columbia, MD). Multiple dwell positions were used, and the dose was optimized to the target volume. The target volume was defined as volume from the balloon surface to 1-cm distance from the balloon surface or to the phantom surface (if less then 1cm from the balloon surface). Target volume coverage was compared between plans using dose-volume histograms. Surface doses were compared using isodose line distribution and surface point doses. Plato planned surface doses were then verified by direct measurement using Landauer Dot InLight dosimeters (Landauer, Glenwood, IL).

RESULTS

Excellent target coverage was obtained for all three catheter orientations with a D(95) of > or =95%. Surface dose was lowest for the perpendicular orientation with a calculated dose of 99%. The parallel orientation had the highest surface dose of 164%. The oblique orientation showed intermediate results with a surface dose of 117%. Measured surface doses were reproducible and correlated well with calculated values.

CONCLUSION

Optimized Xoft Axxent balloon catheter orientation using source anisotropy and multiple dwell positions can be used to minimize excessive skin dose and yet maintain optimal tumor cavity coverage when the cavity to skin distance is small. This has the potential to decrease skin late effects and improve cosmetic outcome. Further clinical study is warranted.

Partial breast irradiation as sole therapy for low risk breast carcinoma: early toxicity, cosmesis and quality of life results of a MammoSite brachytherapy phase II study

PURPOSE

The MammoSite is a device that was developed with the goal of making breast-conserving surgery (BCT) more widely available. Our objective was to evaluate the MammoSite device performances after an open cavity placement procedure and quality of life in highly selected patients with early-stage breast cancer.

METHODS AND MATERIALS

From March 2003 to March 2005, 43 patients with T1 breast cancer were enrolled in a phase II study. The median age was 72 years. Twenty-five (58%) patients were treated with high-dose rate brachytherapy using the MammoSite applicator to deliver 34Gy in 10 fractions. The main disqualifying factor was pathologic sentinel node involvement (10/43; 23%). There were no device malfunctions, migration or rupture of the balloon.

RESULTS

After a median follow-up of 13 months, there were no local recurrences and one contralateral lobular carcinoma. Seventeen (68%), 13 (52%), 8 (32%), 5 (20%) and 2 (8%) patients had erythema, seroma, inflammation, hematoma and sever infection, respectively. Only 2 patients developed telangiectasia. At 1 year the rate of "good to excellent" cosmetic results was 84%. Significant changes in QoL were observed for emotional and social well-being between 3 and 12 months. At 24 months, only emotional well-being subscore changes were statistically significant (p=0.015).

CONCLUSIONS

Our data in patients older than 60 years support the previously published data. Histologic features were the main disqualifying criteria. With higher skin spacing levels we observed very low incidence of telangiectasia. QoL evaluation indicates that baseline scores were satisfactory. Changes concerned emotional and social well-being.

[Accelerated partial breast irradiation: a concept to individualize treatment in breast cancer]

Whole breast irradiation delivering an equivalent dose of 50 Gy in 5 weeks, followed by a 10 to 16 Gy-boost to the tumor bed is the standard of care after breast-conserving surgery for early-breast cancer. Accelerated partial breast irradiation (APBI) is currently under investigations in large multi-institutional, prospective, randomized trials to objectively address the critical endpoints of treatment efficacy, toxicity and cosmesis. Patient's selection for this new approach is crucial to individualise treatments and define the subgroups of patients who will really benefit from APBI in terms of quality of life without decreasing long-term results of the disease control and cosmesis. In this review, we will discuss the patients' profiles selection for APBI regarding their general and tumor criteria. The differences between APBI techniques either performed intra or post operatively will be also discussed.

Integrating Partial Breast Irradiation into Surgical Practice and Clinical Trials

The use of accelerated partial breast irradiation (APBI) in place of whole-breast irradiation (WBI) for breast-conservation therapy (BCT) is an area of intensive clinical investigation. This article describes evolving methods of APBI in comparison to WBI and in the setting of ongoing clinical trials.

Technology Insight: MammoSite®—a new device for delivering brachytherapy following breast-conserving therapy

The MammoSite (Cytyc Corporation, Marlborough, MA) breast brachytherapy applicator was designed to overcome the logistic problems created by external-beam radiation therapy (EBRT) and the technical difficulties associated with multicatheter-based interstitial brachytherapy. The MammoSite catheter has been shown to treat a volume of tissue equivalent to that treated by multicatheter-based brachytherapy. Using ultrasound guidance, the MammoSite applicator can be placed using an open technique at the time of lumpectomy or post-lumpectomy. Initial results have shown favorable cosmesis and few significant side effects. NSABP B-39/RTOG 0413 randomizes patients between EBRT and partial-breast irradiation (PBI). The PBI arm consists of interstitial brachytherapy, MammoSite brachytherapy, or 3D conformal EBRT. This trial has the potential to provide a definitive answer regarding the benefits of PBI for certain subgroups of patients, and hence lead to more women undergoing breast conservation therapy.

Radiation Therapy in the Treatment of Breast Cancer

OBJECTIVES

To explore the advancements in radiation therapy for patients with breast cancer. To review the side effects associated with radiation therapy to the breast.

DATA SOURCES

Medical and nursing journals and texts.

CONCLUSION

Advances in technology and a shift in the paradigm used to treat breast cancer are leading to newer and accelerated methods of treatment. APBI has gained increased attention and is the subject of numerous clinical trials.

IMPLICATIONS FOR NURSING PRACTICE

Nurses must be aware of the technical aspects associated with new technology and the rationale and implications associated with its use. The focus for nurses working in radiation therapy continues to be patient education and side effect management. Nurses must understand the ramifications such treatment entails so as to provide optimal care.

Radiation Options for Early Stage Breast Cancer

OBJECTIVE

To explore the current radiation therapy options for early stage breast cancer.

DATA SOURCES

Research literature and review articles.

CONCLUSION

With 20 years of clinical data supporting the efficacy of whole breast radiotherapy after lumpectomy for early stage breast cancer, the attention has shifted to an even more conservative approach, namely partial breast irradiation following lumpectomy. A number of large clinical trials in North America and Europe are currently enrolling patients for the evaluation of several different techniques, including interstitial brachytherapy, the Mammosite device, 3-dimensional conformal external radiation therapy, and intraoperative radiotherapy.

IMPLICATIONS FOR NURSING PRACTICE

Radiation oncology nurses can significantly impact the coordination of services and the education of patients who enroll in these important clinical trials.

Radiation therapy in the elderly

The purpose of this review is to highlight aspects of radiation oncology specifically related to aging and caring for the older patient with cancer. Particular emphasis is placed on the preclinical and clinical studies focusing on the efficacy and toxicity of RT in this population. Special techniques are also reviewed that have particular relevance to the treatment of the elderly.

Descriptions and outcomes of insertion techniques of a breast brachytherapy balloon catheter in 1403 patients enrolled in the American Society of Breast Surgeons MammoSite breast brachytherapy registry trial

BACKGROUND

The use of the MammoSite brachytherapy balloon catheter is 1 option for the delivery of accelerated partial breast irradiation during breast cancer therapy. The device can be inserted into the breast using 3 different techniques. This report describes these methods of insertion and correlates the technique with outcome data collected in a multi-institutional registry trial.

METHODS

In the registry trial, MammoSite catheters were inserted either (1) at the time of lumpectomy into an open cavity, (2) after surgery with ultrasound guidance through a separate small lateral incision into a closed cavity, or (3) after surgery by entering directly through the lumpectomy wound (the scar entry technique). Device placement techniques in 1403 patients with early stage breast cancer treated at 87 institutions by 223 different investigators were documented in the registry. Data collected included number of cases of each technique, age of patient, tumor size, skin spacing, catheter pull rates and reasons, infection, radiation recall, cosmesis, and recurrence.

RESULTS

Catheter placement at the time of lumpectomy was performed in 619 patients (44%), after surgery with ultrasound guidance in 576 patients (41%), and the scar entry technique technique in 197 patients (14%). The type of technique was not associated with age of patient, tumor size, bra size, catheter size, skin spacing, infection, radiation recall, cosmesis, or recurrence. There was a statistically significant increased incidence of premature catheter removals for pathologically related reasons with the open-cavity technique compared with the 2 postoperative methods secondary to final histology reports disqualifying the patient after MammoSite placement.

CONCLUSIONS

These registry data show that the MammoSite catheter can be inserted with any 1 of 3 different techniques. A postoperative placement, after the final pathology report is issued, decreases the incidence of premature removal of the catheter because of disqualifying pathology.