Cosmetic Outcome and Incidence of Infection with the MammoSite Breast Brachytherapy Applicator

Patterns of use and short-term complications of breast brachytherapy in the national medicare population from 2008-2009

PURPOSE

Brachytherapy has disseminated into clinical practice as an alternative to whole-breast irradiation (WBI) for early-stage breast cancer; however, current national treatment patterns and associated complications remain unknown.

PATIENTS AND METHODS

We constructed a national sample of Medicare beneficiaries ages 66 to 94 years who underwent breast-conserving surgery from 2008 to 2009 and were treated with brachytherapy or WBI. We used hospital referral regions (HRRs) to assess national treatment variation and an instrumental variable analysis to compare complication rates between treatment groups, adjusting for patient and clinical characteristics. We compared overall, wound and skin, and deep-tissue and bone complications between brachytherapy and WBI at 1 year of follow-up.

RESULTS

Of 29,648 women in our sample, 4,671 (15.8%) received brachytherapy. The percent of patients receiving brachytherapy varied substantially across HRRs, ranging from 0% to over 70% (interquartile range, 7.5% to 23.3%). Of women treated with brachytherapy, 34.3% had a complication compared with 27.3% of women undergoing WBI (P < .001). After adjusting for patient and clinical characteristics, 35.2% of women treated with brachytherapy (95% CI, 28.6 to 41.9) had a complication compared with 18.4% treated with WBI (95% CI, 15.5 to 21.3; P value for difference, <.001). Brachytherapy was associated with a 16.9% higher rate of wound and skin complications compared with WBI (95% CI, 10.0 to 23.9; P < .001), but there was no difference in deep-tissue and bone complications.

CONCLUSION

Brachytherapy is commonly used among Medicare beneficiaries and varies substantially across regions. After 1 year, wound and skin complications were significantly higher among women receiving brachytherapy compared with those receiving WBI.

Brachytherapy in accelerated partial breast irradiation (APBI) - review of treatment methods

Breast conserving surgery (BCS) with following radiotherapy (EBRT) of the conserved breast became widely accepted in the last decades as the treatment of early invasive breast cancer. In an early stage of breast cancer, research has shown that the area requiring radiation treatment to prevent cancer from local recurrence is the breast tissue that surrounds the area where the initial cancer was removed. Accelerated partial breast irradiation (APBI) is an approach that treats only the lumpectomy bed with 1-2 cm margin, rather than the whole breast and as a result allows accelerated delivery of the radiation dose in four to five days. Published results of APBI are very promising. It is evident that APBI will play a role in the management of a selected group of early breast cancer. We discuss current status, indications, technical aspects and recently published results of APBI using different brachytherapy techniques.

Determination of exit skin dose for 192Ir intracavitary accelerated partial breast irradiation with thermoluminescent dosimeters

PURPOSE

Intracavitary accelerated partial breast irradiation (APBI) has become a popular treatment for early stage breast cancer in recent years due to its shortened course of treatment and simplified treatment planning compared to traditional external beam breast conservation therapy. However, the exit dose to the skin is a major concern and can be a limiting factor for these treatments. Most treatment planning systems (TPSs) currently used for high dose-rate (HDR) 192Ir brachytherapy overestimate the exit skin dose because they assume a homogeneous water medium and do not account for finite patient dimensions. The purpose of this work was to quantify the TPS overestimation of the exit skin dose for a group of patients and several phantom configurations.

METHODS

The TPS calculated skin dose for 59 HDR 192Ir APBI patients was compared to the skin dose measured with LiF:Mg,Ti thermoluminescent dosimeters (TLDs). Additionally, the TPS calculated dose was compared to the TLD measured dose and the Monte Carlo (MC) calculated dose for eight phantom configurations. Four of the phantom configurations simulated treatment conditions with no scattering material beyond the point of measurement and the other four configurations simulated the homogeneous scattering conditions assumed by the TPS. Since the calibration TLDs for this work were irradiated with 137Cs and the experimental irradiations were performed with 192Ir, experiments were performed to determine the intrinsic energy dependence of the TLDs. Correction factors that relate the dose at the point of measurement (center of TLD) to the dose at the point of interest (basal skin layer) were also determined and applied for each irradiation geometry.

RESULTS

The TLD intrinsic energy dependence for 192Ir relative to 137Cs was 1.041 +/- 1.78%. The TPS overestimated the exit skin dose by an average of 16% for the group of 59 patients studied, and by 9%-15% for the four phantom setups simulating treatment conditions. For the four phantom setups simulating the conditions assumed by the TPS, the TPS calculated dose agreed well with the TLD and MC results (within 3% and 1%, respectively). The inverse square geometry correction factor ranged from 1.023 to 1.042, and an additional correction factor of 0.978 was applied to account for the lack of charged particle equilibrium in the TLD and basal skin layer.

CONCLUSIONS

TPS calculations that assume a homogeneous water medium overestimate the exit skin dose for intracavitary APBI treatments. It is important to determine the actual skin dose received during intracavitary APBI to determine the skin dose-response relationship and establish dose limits for optimal skin sparing. This study has demonstrated that TLDs can measure the skin dose with an expanded uncertainty (k = 2) of 5.6% when the proper corrections are applied.

Review of MammoSite brachytherapy: advantages, disadvantages and clinical outcomes

BACKGROUND

The MammoSite radiotherapy system is an alternative treatment option for patients with early-stage breast cancer to overcome the longer schedules associated with external beam radiation therapy. The device is placed inside the breast surgical cavity and inflated with a combination of saline and radiographic contrast to completely fill the cavity. The treatment schedule for the MammoSite monotherapy is 34 Gy delivered in 10 fractions at 1.0 cm from the balloon surface with a minimum of 6 hours between fractions on the same day.

MATERIAL AND METHODS

This review article presents the advantages, disadvantages, uncertainties and clinical outcomes associated with the MammoSite brachytherapy (MSB).

RESULTS

Potential advantages of MSB are: high localised dose with rapid falloff for normal tissue sparing, minimum delay between surgery and RT, catheter moves with breast, improved local control, no exposure to staff, likely side-effects reduction and potential cost/time saving (e.g. for country patients). The optimal cosmetic results depend on the balloon-to-skin distance. Good-to-excellent cosmetic results are achieved for patients with balloon-skin spacing of > or =7 mm. There have been very few published data regarding the long term tumour control and cosmesis associated with the MSB. The available data on the local control achieved with the MSB were comparable with other accelerated partial breast irradiation techniques. The contrast medium inside the balloon causes dose reduction at the prescription point. Current brachytherapy treatment planning systems (BTPS) do not take into account the increased photon attenuation due to high Z of contrast. Some BTPS predicted up to 10% higher dose near the balloon surface compared with Monte Carlo calculations using various contrast concentrations (5-25%).

CONCLUSION

Initial clinical results have shown that the MammoSite device could be used as a sole radiation treatment for selected patients with early stage breast cancer providing good local control, minimal complication rate and excellent cosmesis.

Accelerated partial breast irradiation as part of breast conserving therapy of early breast carcinoma: a systematic review

New strategies for adjuvant radiotherapy of early breast cancer are being investigated in several phase III randomised trials at the present time. Accelerated partial breast irradiation (APBI) is a way to offer an early breast cancer patient, who has had breast conservative surgery, an adjuvant radiotherapy of short duration aimed at the tumour bed with a certain margin. The rationale of this strategy is that most local recurrences appear close to the tumorectomy cavity and a wish to spare the patient late radiation morbidity. This review discusses the background for APBI, the different techniques, and we highlight possible pitfalls using these techniques. A systematic overview of all phase I and II studies is provided. Patient selection for this therapy is pivotal and based on evidence from previous studies on patient/tumour characteristics and pattern of local recurrences we propose inclusion criteria for patients in APBI protocols.

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.

New trends in radiotherapy for breast cancer

PURPOSE OF REVIEW

New radiotherapy techniques are under development to improve tumor control and to decrease the long-term side effects of breast cancer. These include accelerated partial breast irradiation, intensity modulated and image guided radiotherapy.

RECENT FINDINGS

Follow-up data of multicatheter brachytherapy accelerated partial breast irradiation and intraoperative electron beam radiotherapy confirm excellent 5-year local control rates in well selected patients. Early side effects seem to be improved, but recent data show increasing skin toxicity in multicatheter and intracavitary balloon brachytherapy. Intraoperative radiotherapy, proton beam partial breast irradiation, intensity modulated and image guided radiotherapy improve dose homogeneity and decrease normal tissue complication probability. For breast-only treatment, two tangential fields with different segments provide an attractive and feasible alternative to the conventional technique. The proposed intensity modulated radiotherapy techniques for comprehensive locoregional radiotherapy, however, result in increased doses to the contralateral lung and breast.

SUMMARY

Input from long-term clinical data on new radiotherapy techniques is needed. Consensus on target volume contouring and dose volume constraints for nontarget tissue has not yet been reached. Further research on skin toxicity with multicatheter or intracavitary brachytherapy is needed to improve the results.

[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.

A dosimetric comparison of MammoSite high-dose-rate brachytherapy and Xoft Axxent electronic brachytherapy

PURPOSE

Over 20,000 patients have been treated with partial breast irradiation (PBI) using the MammoSite balloon brachytherapy applicator (IBB). Recently, a new form of balloon-based PBI, Xoft Axxent electronic brachytherapy (KVB), which uses a 50-kV x-ray source, has been introduced. This analysis was undertaken to dosimetrically compare the results of treatment using these two methods of PBI.

METHODS AND MATERIALS

The study population consisted of 15 patients previously treated with IBB. The planning CT scans from these 15 patients were used to construct hypothetical treatment plans using the source characteristics of the KVB device. The plans were then compared using the dosimetric parameters discussed below.

RESULTS

The mean %V(90) was 99.6% vs. 99.0% (p=nonsignificant [ns]), the mean %V(100) was 96.5% vs. 96.5%, the mean %V(150) was 41.8% vs. 59.4% (p<0.05), the mean %V(200) was 11.3% vs. 32.0% (p<0.05), and the mean %V(300) was 0.4% vs. 6.7% (p<0.05) for the IBB and KVB methods, respectively. The mean ipsilateral breast %V(50) was 19.8% vs. 13.0% (p<0.05), the mean ipsilateral lung %V(30) was 3.7% vs. 1.1% (p<0.05), and the mean heart %V(5) was 59.2% vs. 9.4% (p<0.05) for the IBB and KVB methods, respectively.

CONCLUSIONS

The IBB and KVB methods of PBI offer comparable target volume coverage; however, the KVB method is associated with an increased volume of breast tissue in the high-dose regions and a decreased dose to the adjacent normal tissues.

Predictors of cosmetic outcome following MammoSite breast brachytherapy: a single-institution experience of 100 patients with two years of follow-up

PURPOSE

To identify the factors that predict for excellent cosmesis in patients who receive MammoSite breast brachytherapy (MBT).

METHODS AND MATERIALS

One hundred patients with Stage 0, I, or II adenocarcinoma of the breast underwent adjuvant therapy using MBT. A dose of 34 Gy, delivered in 10 fractions twice daily, was prescribed to 1-cm depth using (192)Ir high-dose-rate brachytherapy. Patients were assessed for acute toxicity on the day of therapy completion, 4 weeks after therapy, and at least every 3 months by radiation, surgical, and/or medical oncologists. All available data were reviewed for documentation of cosmesis and rated using the Harvard Scale. All patients had a minimum follow-up of 6 months (median = 24 months).

RESULTS

Of 100 patients treated, 90 had adequate data and follow-up. Cosmesis was excellent in 62 (68.9%), good in 19 (21.1%), fair in 8 (8.9%), and poor in 1 (1.1%) patient. Using stepwise logistic regression, the factors that predicted for excellent cosmesis were as follows: the absence vs. presence of infection (p = 0.017), and the absence vs. presence of acute skin toxicity (p = 0.026). There was a statistically significant association between acute skin toxicity (present vs. absent) and balloon-to-skin distance (<8 vs. >8 mm, p = 0.001). Factors that did not predict for cosmesis were age, balloon placement technique, balloon volume, catheter days in situ, subcutaneous toxicity, and chemotherapy or hormonal therapy.

CONCLUSIONS

The acute and late-term toxicity profiles of MBT have been acceptable. Cosmetic outcome is improved by proper patient selection and infection prevention.

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.

Evaluation of the surface radiation dose and dose gradient in early stage breast cancer using high-dose-rate brachytherapy MammoSite™ applicator

PURPOSE

To monitor the radiation dose delivered and dose homogeneity to the skin and adjacent tissues around a MammoSite applicator.

METHODS AND MATERIALS

Radiation surface dose was measured on 67 consecutive patients with Stage T1-T2N0M0 breast cancer implanted with the MammoSite balloon. Thermoluminescent dosimeters and metal oxide semiconductor field effect transistors were used to measure surface dose directly over the balloon, contralateral breast, thyroid, axilla, and inframammary fold. The dose homogeneity was retrospectively studied from the treatment plans in 25 patients.

RESULTS

The mean maximum skin dose was 267 cGy, with a range of 56-488 cGy per fraction, 4 cGy (+/-2 cGy) to the contralateral breast, 8 cGy (+/-4 cGy) to the thyroid, 47 cGy to the ipsilateral axilla (+/-33 cGy), and 52 cGy (+/-47 cGy) to the ipsilateral inframmammary fold. The mean dose gradients were 127%, 110%, 99%, 96%, and 89% for inflated volumes of 35, 40, 50, 60, and 70 mL, respectively.

CONCLUSIONS

All patients completed therapy with no or minimal skin reaction with radiation doses comparable to or better to external beam radiation. Considering the dose homogeneity, the larger inflated volume allows for better homogeneity of dose distribution, minimizes the volume of contiguous tissue that receives relatively high doses, and may reduce the risk of fat necrosis.

Accelerated partial breast irradiation using interstitial high dose rate 192iridium brachytherapy: Early Australian experience and review of the literature

Summary Accelerated partial breast irradiation (APBI) is an evolving new technique of adjuvant irradiation in selected women with early-stage breast cancer. We developed a pilot programme of APBI in 2000 and report end results in seven patients followed for a mean of 42.7 months (range 29-55 months). Good to excellent cosmesis and no loco-regional relapse or systemic metastases have occurred. The literature related to APBI is reviewed.

The MammoSite® breast brachytherapy device: targeted delivery of breast brachytherapy

The MammoSite® breast brachytherapy device was designed to overcome the logistic difficulties presented by external beam radiation therapy and the technical difficulties of multicatheter-based interstitial brachytherapy. The device consists of a silicone balloon connected to a catheter which contains an inflation channel and a port for passage of a high-dose-rate brachytherapy source. The American Brachytherapy Society and American Society of Breast Surgeons have published partial breast irradiation patient selection guidelines. Initial reports have shown a favorable cosmetic outcome in the majority of patients. The MammoSite applicator has also been associated with minimal side effects. The NSABP B-39/RTOG 0413 trial will randomize patients to either whole breast irradiation or partial-breast irradiation consisting of interstitial brachytherapy, MammoSite brachytherapy, or 3D conformal radiation. This national randomized trial has the potential to provide a definitive answer regarding the benefits of partial-breast irradiation, and therefore lead to more women undergoing breast conserving therapy.