Acute complications of MammoSite brachytherapy: A single institution's initial clinical experience

A case of cetuximab-induced radiation recall skin dermatitis and review of the literature

Radiation recall presents as an acute inflammatory reaction triggered by systemic therapy, usually chemotherapy, and is typically limited to an area that was previously irradiated. Radiation recall reactions are generally self-limiting and most commonly occur in the skin. Many systemic agents have been described to elicit a radiation recall reaction, but the exact pathogenesis is largely unknown. Here, we describe the first reported case of radiation recall dermatitis following cetuximab. While cetuximab is associated with other skin reactions, oncologists should not exclude radiation recall dermatitis as a potential complication of cetuximab infusion in patients with prior radiation, and special attention should be paid to the pattern of skin changes both in terms of location and chronology.

Mono-institutional Italian Experience with a Double-lumen Balloon-brachytherapy Device for Early Breast Cancer: Results at a 5-year Minimum follow-up

Aims and Background

To report the 5-year minimum follow-up in low-risk breast cancer patients treated with a double-lumen balloon-brachytherapy device in one mono-institutional Italian experience. Local control data and cosmetic outcomes were collected and analyzed.

Methods

Between October 2004 and December 2007, we treated 30 early stage breast cancer patients who underwent conservative surgery followed by adjuvant accelerated partial breast irradiation with a double-lumen balloon-brachytherapy system. Eligibility criteria for the protocol were based on the indications of the American Brachytherapy Society and the American Society of Breast Surgeons. The device was placed inside the lumpectomy cavity during surgery by open technique in all the patients. Computed tomography images and standard X-ray were used for treatment planning. The total irradiation dose was 34 Gy in 10 fractions of 3.4 Gy (twice daily) over 5 days to the lumpectomy cavity.

Results

Median follow-up was 80.5 months (range, 60–98). No patient developed local recurrence or distant metastasis. At the end of treatment, there was evidence of a symptomatic seroma in 83% of the total patients, with a yearly decreasing trend. However, the incidence of mild and moderate fibrosis progressively increased. Seventy seven percent of the patients were satisfied with their cosmetic results.

Conclusions

Our findings reinforce the hypothesis that an accelerated double-lumen balloon-breast brachytherapy catheter in selected low-risk patients is safe, and a favorable cosmetic outcome can be achieved.

Contemporary Toxicity Profile of Breast Brachytherapy Versus External Beam Radiation After Lumpectomy for Breast Cancer

PURPOSE

We compared toxicities after brachytherapy versus external beam radiation therapy (EBRT) in contemporary breast cancer patients.

METHODS AND MATERIALS

Using MarketScan healthcare claims, we identified 64,112 women treated from 2003 to 2012 with lumpectomy followed by radiation (brachytherapy vs EBRT). Brachytherapy was further classified by multichannel versus single-channel applicator approach. We identified the risks and predictors of 1-year infectious and noninfectious postoperative adverse events using logistic regression and temporal trends using Cochran-Armitage tests. We estimated the 5-year Kaplan-Meier cumulative incidence of radiation-associated adverse events.

RESULTS

A total of 4522 (7.1%) patients received brachytherapy (50.2% multichannel vs 48.7% single-channel applicator). The overall risk of infectious adverse events was higher after brachytherapy than after EBRT (odds ratio [OR] = 1.21; 95% confidence interval [CI] 1.09-1.34, P<.001). However, over time, the frequency of infectious adverse events after brachytherapy decreased, from 17.3% in 2003 to 11.6% in 2012, and was stable after EBRT at 9.7%. Beyond 2007, there were no longer excess infections with brachytherapy (P=.97). The overall risk of noninfectious adverse events was higher after brachytherapy than after EBRT (OR=2.27; 95% CI 2.09-2.47, P<.0001). Over time, the frequency of noninfectious adverse events detected increased: after multichannel brachytherapy, from 9.1% in 2004 to 18.9% in 2012 (Ptrend = .64); single-channel brachytherapy, from 12.8% to 29.8% (Ptrend<.001); and EBRT, from 6.1% to 10.3% (Ptrend<.0001). The risk was significantly higher with single-channel than with multichannel brachytherapy (hazard ratio = 1.32; 95% CI 1.03-1.69, P=.03). Of noninfectious adverse events, 70.9% were seroma. Seroma significantly increased breast pain risk (P<.0001). Patients with underlying diabetes, cardiovascular disease, and treatment with chemotherapy had increased infectious and noninfectious adverse events. The 5-year incidences of fat necrosis, breast pain, and rib fracture were slightly higher after brachytherapy than after EBRT (13.7% vs 8.1%, 19.4% vs 16.0%, and 1.6% vs 1.3%, respectively), but the risks were not significantly different for multichannel versus single-channel applicators.

CONCLUSION

Toxicities after breast brachytherapy were distinct from those after EBRT. Temporal toxicity trends may reflect changing technology and evolving practitioner experience with brachytherapy.

Brachytherapy treatment planning commissioning: effect of the election of proper bibliography and finite size of TG-43 input data on standard treatments

The aim of this work is to evaluate the performance of a commercial brachytherapy treatment planning system (TPS) with TG‐43 Vendors Input Data (VID), analyze possible discrepancies with respect to a proper reference source and its implications for standard treatments, and judge the effectiveness of certain widespread recommended quality controls to find potential errors related with the interpolations of TG‐43 VID tables. The TPS evaluated was a BrachyVision 8.6 loaded with TG‐43 VID for a VariSource high‐dose‐rate 192Ir source (Vs2000). The reference data chosen were the TG‐43 data published in the literature. In the first step, we compared TG‐43 VID with respect to the chosen reference data. Next, we used percent dose‐rate differences in a point array matrix to compare the outcomes of the TPS on standard treatment setup with respect to an in‐house developed program (MATLAB R2009a‐based) loaded with the chosen full TG‐43 reference data. The cases with major discrepancies were evaluated using the gamma‐index analysis. The comparison with the reference data indicated a lack of sample in the angles between near to the tip (between 165<θ<180) and cable (0<θ<15) of the F(r,θ)VID, which causes a dose underestimation of approximately 17% in the investigated points due to inaccurate interpolations. The differences over 2% encompassed approximately 17% of the surrounding source volume. These results have special relevance in treatment using one applicator with a few dwell steps or in Fletcher treatments where 10% dose underestimates were identified within the tumor or in organs at risk, respectively. Our results suggest that the differences found in the TPS under study are created by a lack of information on the angles in high‐gradient zones in the F(r,θ)VID, which generates important differences in dosimetric results. In contrast, the gamma analysis shows very good results (between 90% and 100% of passed points) in the analyzed treatments (one dwell and Fletcher). Further studies are required to exclude the possibility of finding noticeable effects in the DVH of treatment plans caused by the discrepancies here described. To achieve more strict control over the TPS dose‐rate calculation, we recommend using QA test thinking in a source with nonaxial symmetry, adding a control point on the angles of the high‐dose gradient zones (e.g., between 0° and 15° and between 165° and 180°). More studies are required to achieve full understanding of the clinical implication of such discrepancies.

PACS number: 87.55.Qr

Partial–breast irradiation: towards a replacement for whole–breast irradiation?

Largely thanks to all of the investigators and patients who have participated in randomized breast-conservation trials, many women facing a diagnosis of breast cancer today can conserve their breast with the help of adjuvant radiation therapy. A standard course of radiation consists of 5-7 weeks of daily radiation treatments delivered to the whole breast. The success of this treatment has led investigators to attempt to determine whether the same control can be achieved while decreasing the volume of breast tissue irradiated, thus allowing treatment to be delivered in a shorter period of time. This approach could alleviate time and logistical problems faced by patients during their course of treatment as well as improving overall cost-effectiveness. It can also allow complete avoidance of the adjacent heart and lung tissue in the radiation treatment portal. Partial-breast irradiation (the delivery of radiation to the resection cavity, plus a safety margin) delivered in just hours or days, is currently under investigation. Although relatively new, its use is growing rapidly and many institutional and cooperative group trials are quickly enlisting patients, while physicians are gaining experience in a variety of partial-breast irradiation techniques.

MammoSite®

MammoSite is a novel brachytherapy applicator for breast irradiation as a component of breast conservation therapy in the management of early stage breast carcinoma. Early stage breast cancer accounts for over two-thirds of newly diagnosed cases. Breast conservation therapy is an option for most women for local therapy. The standard treatment of partial mastectomy and whole-breast irradiation is being challenged. Physicians and patients are searching for alternatives to a 6- to 7-week course of external beam radiation therapy. The direct application of radioactive materials (brachytherapy) in this setting has been employed for over 10 years. MammoSite has been developed as an easier, more quality assured applicator to allow broader acceptance and wider availability of partial breast irradiation techniques. The background leading to the device will be examined, current clinical results will be reviewed and alternative technologies will be discussed.

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.

Breast cancer recurrence after inadvertent malpositioning of a partial breast radiation catheter

Accelerated partial breast irradiation (APBI) is an alternative to receiving whole breast radiation in carefully selected patients. Because breast cancer local recurrence rates are low and follow-up has been short-term, the exact cause of recurrences after APBI has been difficult to evaluate. We report the first case of documented radiation balloon catheter malpositioning that resulted in local recurrence. Patients undergo CT imaging of the breast after radiation balloon catheter placement for radiotherapy treatment planning, which evaluates adequate conformance of the balloon to the surrounding breast parenchyma and confirms a >7 mm distance between the balloon surface and the skin surface. Although true local recurrences are rare in appropriately selected partial breast irradiation candidates, inadvertent malpositioning of the radiation treatment catheter can increase the risk. This case is presented to illustrate the importance of comparing CT radiation planning images, with treatment catheter in place, to the original diagnostic breast imaging studies to confirm proper catheter positioning (in addition to measuring balloon to skin distance and conformance) prior to initiating radiotherapy.

Dosimetric evaluation of 3Dconformal acceleratedpartial-breast irradiation vs. whole-breast irradiation: A comparative study

Background:

Conventional early breast cancer treatment consists of lumpectomy followed by whole-breast irradiation (WBI) therapy. Accelerated partial-breast irradiation (APBI) is also an approach to post-lumpectomy radiation for early breast cancer.

Aim:

The purpose of this study is to compare two different external-beam APBI techniques using three-dimensional (3D) conformal radiation therapy (3DCRT), with conventional whole-breast irradiation based on the radiation conformity index, dose homogeneity index, and dose to organs at risk.

Materials and Methods:

WBI treatment plans were compared with two different 3DCRT APBI plans for each of 15 patients (8 with right sided lesions, 7 with left sided lesions). The first APBI plan (APBI 1) used two small coplanar fields conformed to the planning target volume (PTV) using multileaf collimators (MLCs) and wedges, while the other APBI plan (APBI 2) used three non-coplanar fields conformed to the PTV using MLCs and wedges.

Results:

Both the APBI techniques improved the conformity index significantly over whole-breast tangents while maintaining dose homogeneity and not causing significant increase in dose to organs at risk.

Conclusion:

Both the 3DCRT APBI techniques are technically feasible and dosimetrically appealing,with better target coverage and relative sparing of normal critical organs

Post-surgical treatment of early-stage breast cancer with electronic brachytherapy: an intersociety, multicenter brachytherapy trial

INTRODUCTION

Electronic brachytherapy (EBT) was developed to allow accelerated partial breast irradiation to be performed in a patient procedure room with minimal shielding. This observational, nonrandomized, multicenter study evaluated EBT as a post-surgical adjuvant radiation therapy for early stage breast cancer.

METHODS

This study included women aged 50 years or more with invasive carcinoma or ductal carcinoma in situ, tumor size ≤3 cm, negative lymph node status, and negative surgical margins. The endpoints were skin and subcutaneous toxicities, efficacy outcomes, cosmetic outcomes, and device performance. In this interim report, 1-month, 6-month, and 1-year follow-up data are available on 68, 59, and 37 patients, respectively.

RESULTS

The EBT device performed consistently, delivering the prescribed 34 Gy to all 69 patients (10 fractions/patient). Most adverse events were Grade 1 and included firmness, erythema, breast tenderness, hyperpigmentation, pruritis, field contracture, seroma, rash/desquamation, palpable mass, breast edema, hypopigmentation, telangiectasia, and blistering, which were anticipated. Breast infection occurred in two (2.9%) patients. No tumor recurrences were reported. Cosmetic outcomes were excellent or good in 83.9%-100% of evaluable patients at 1 month, 6 months, and 1 year.

CONCLUSION

This observational, nonrandomized, multicenter study demonstrates that this EBT device was reliable and well tolerated as an adjuvant radiation therapy for early stage breast cancer.

Experience with an electronic brachytherapy technique for intracavitary accelerated partial breast irradiation

OBJECTIVES

Phase IV study evaluated the safety and device performance of an electronic brachytherapy system (Axxent Electronic Brachytherapy System) as adjuvant therapy for early-stage breast cancer.

METHODS

Patients were > or =50 years of age and had completely resected invasive ductal carcinoma or ductal carcinoma in situ (<2.0 cm), with N0 M0 and negative microscopic margins of > or =1 mm. The balloon applicator was placed in a closed cavity with a balloon surface to skin distance of > or =7 mm. The prescribed dose was 3.4 Gy/fraction prescribed to 1 cm beyond the balloon surface twice daily (BID) for 10 fractions.

RESULTS

Of 65 patients consented, 21 (32%) were not eligible for treatment, and 44 (68%) were treated, with 6-months follow-up in 43 and 1-year follow-up in 36. The prescribed radiation treatment was successfully delivered in 42/44 (95.4%) patients; one was unsuccessful due to a controller issue and the other declined the final fraction following a balloon deflation. Side effects were as anticipated and generally manageable. Four CTCAE v3 grade 3 toxicities were reported: blistering (1), breast tenderness (1), and moist desquamation (2); all have resolved. The most common grade 2 toxicity was erythema. There were no device-related serious adverse events.

CONCLUSIONS

Early experience demonstrates that the electronic brachytherapy system performed as expected. Electronic brachytherapy has similar acute toxicity profiles to other high dose rate approaches for accelerated partial breast irradiation and offers the convenience of having the treatment in an unshielded room.

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.

Five-year analysis of treatment efficacy and cosmesis by the American Society of Breast Surgeons MammoSite Breast Brachytherapy Registry Trial in patients treated with accelerated partial breast irradiation

PURPOSE

To present 5-year data on treatment efficacy, cosmetic results, and toxicities for patients enrolled on the American Society of Breast Surgeons MammoSite breast brachytherapy registry trial.

METHODS AND MATERIALS

A total of 1440 patients (1449 cases) with early-stage breast cancer receiving breast-conserving therapy were treated with the MammoSite device to deliver accelerated partial-breast irradiation (APBI) (34 Gy in 3.4-Gy fractions). Of 1449 cases, 1255 (87%) had invasive breast cancer (IBC) (median size, 10 mm) and 194 (13%) had ductal carcinoma in situ (DCIS) (median size, 8 mm). Median follow-up was 54 months.

RESULTS

Thirty-seven cases (2.6%) developed an ipsilateral breast tumor recurrence (IBTR), for a 5-year actuarial rate of 3.80% (3.86% for IBC and 3.39% for DCIS). Negative estrogen receptor status (p=0.0011) was the only clinical, pathologic, or treatment-related variable associated with IBTR for patients with IBC and young age (<50 years; p=0.0096) and positive margin status (p=0.0126) in those with DCIS. The percentage of breasts with good/excellent cosmetic results at 60 months (n=371) was 90.6%. Symptomatic breast seromas were reported in 13.0% of cases, and 2.3% developed fat necrosis. A subset analysis of the first 400 consecutive cases enrolled was performed (352 with IBC, 48 DCIS). With a median follow-up of 60.5 months, the 5-year actuarial rate of IBTR was 3.04%.

CONCLUSION

Treatment efficacy, cosmesis, and toxicity 5 years after treatment with APBI using the MammoSite device are good and similar to those reported with other forms of APBI with similar follow-up.

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.

Monte Carlo-derived TLD cross-calibration factors for treatment verification and measurement of skin dose in accelerated partial breast irradiation

Monte Carlo simulation was employed to calculate the response of TLD-100 chips under irradiation conditions such as those found during accelerated partial breast irradiation with the MammoSite radiation therapy system. The absorbed dose versus radius in the last 0.5 cm of the treated volume was also calculated, employing a resolution of 20 microm, and a function that fits the observed data was determined. Several clinically relevant irradiation conditions were simulated for different combinations of balloon size, balloon-to-surface distance and contents of the contrast solution used to fill the balloon. The thermoluminescent dosemeter (TLD) cross-calibration factors were derived assuming that the calibration of the dosemeters was carried out using a Cobalt 60 beam, and in such a way that they provide a set of parameters that reproduce the function that describes the behavior of the absorbed dose versus radius curve. Such factors may also prove to be useful for those standardized laboratories that provide postal dosimetry services.

Dose volume histogram analysis of normal structures associated with accelerated partial breast irradiation delivered by high dose rate brachytherapy and comparison with whole breast external beam radiotherapy fields

PURPOSE

To assess the radiation dose delivered to the heart and ipsilateral lung during accelerated partial breast brachytherapy using a MammoSite applicator and compare to those produced by whole breast external beam radiotherapy (WBRT).

MATERIALS AND METHODS

Dosimetric analysis was conducted on patients receiving MammoSite breast brachytherapy following conservative surgery for invasive ductal carcinoma. Cardiac dose was evaluated for patients with left breast tumors with a CT scan encompassing the entire heart. Lung dose was evaluated for patients in whom the entire lung was scanned. The prescription dose of 3400 cGy was 1 cm from the balloon surface. MammoSite dosimetry was compared to simulated WBRT fields with and without radiobiological correction for the effects of dose and fractionation. Dose parameters such as the volume of the structure receiving 10 Gy or more (V10) and the dose received by 20 cc of the structure (D20), were calculated as well as the maximum and mean doses received.

RESULTS

Fifteen patients were studied, five had complete lung data and six had left-sided tumors with complete cardiac data. Ipsilateral lung volumes ranged from 925-1380 cc. Cardiac volumes ranged from 337-551 cc. MammoSite resulted in a significantly lower percentage lung V30 and lung and cardiac V20 than the WBRT fields, with and without radiobiological correction.

CONCLUSION

This study gives low values for incidental radiation received by the heart and ipsilateral lung using the MammoSite applicator. The volume of heart and lung irradiated to clinically significant levels was significantly lower with the MammoSite applicator than using simulated WBRT fields of the same CT data sets.

Late chest wall toxicity after MammoSite breast brachytherapy

PURPOSE

Accelerated partial breast irradiation (APBI) with the MammoSite breast brachytherapy (MBB) system is being investigated as an alternative to whole breast radiation in breast conservation therapy (BCT) at multiple centers worldwide. The newness of MBB means a complete understanding of long-term toxicity, particularly involving the chest wall, has yet to be completely articulated. We report the first pathologic rib fractures associated with MBB and dosimetric analysis of the original treatment plans.

METHODS AND MATERIALS

As part of ongoing quality assurance, we reviewed the records of 129 sequential patients who underwent MBB for breast cancer and identified those who subsequently had clinically significant and radiographically documented rib fracture(s) involving the ipsilateral chest wall. Equivalent tolerance doses yielding a 5% and 50% risk of rib toxicity within 5 years from treatment with 10 fractions (as with MBB) were previously calculated using the linear quadratic equation based on 2Gy per fraction treatments delivered to one-third of the rib volume (TD5/5=37Gy; TD50/5=44Gy). The original radiation therapy plans were evaluated vis-à-vis the plane films or PET/CT images documenting the osseous abnormalities and presenting complaints to find the specific fractured ribs. The specific effected ribs were contoured on the planning CT in "bone windows" using the Nucletron MicroSelectron-classic V2 (Nucletron B.V., Veenendaal, The Netherlands) for this analysis and the original patient treatments. With these datasets, we determined the dose-volume characteristics of the effected ribs including maximal dose encompassing the entire rib on one CT slice, V(20Gy), V(30Gy), V(37Gy), V(44Gy), D(50), D(25), and D(5) (the mean dose to 50%, 25%, and 5% of the rib).

RESULTS

Between May 2002 and August 2007, three of 105 patients with a minimum of 6-months follow-up who underwent adjuvant APBI by MBB were found to have a total of five treatment-related rib fractures. The average dose-volume characteristics from the original plans were as follows: D(50)=22.1Gy, D(25)=32.2Gy, D(5)=41.6Gy, max dose to 1cc=34.8, D(max) (to 0.1cc)=45.6Gy, V(20)Gy=57.4%, V(30)Gy=30.8%, V(37)Gy=15.9%, V(44)Gy=6.6%, and max dose through rib=35.8Gy. Two patients sustained two rib fractures and 1 patient had a single rib fracture. Four of five fractures occurred in postmenopausal patients and two of five fractures occurred in a patient with a history of osteoporosis and exposure to adjuvant chemotherapy.

CONCLUSIONS

Fractures occurred in ribs with V(37)Gy and V(44)Gy each well below 33%. As long-term toxicity data accrue from APBI series, the traditional models for estimating the biologic equivalent dose may benefit from refinements that specifically address the unique radiobiologic and physical properties intrinsic to high-dose-rate brachytherapy for breast conservation therapy.

Patient satisfaction and quality of life after MammoSite breast brachytherapy

PURPOSE

To perform a satisfaction/quality-of-life (QOL) survey of patients undergoing MammoSite brachytherapy (MBT; Hologic, Inc, Marlborough, MA).

METHODS

We asked patients 15 questions regarding treatment decision-making, and experience on-therapy/post-treatment.

RESULTS

A total of 52 patients responded (median follow-up 30 months). Regarding decision-making, 5.8% viewed the avoidance of mastectomy as "not important." If MBT were not available, 55.8% would opt for whole-breast radiotherapy (WBRT) without difficulty, 28.8% would have significant travel/financial difficulty, and 15.4% would refuse radiotherapy/opt for mastectomy. Regarding choice factors, patients selected "focused therapy" (44.2%), "convenience" (36.5%), and "cutting edge" (17.3%). A total of 61.5% patients were not concerned about a second surgical procedure; 90.4% were not/somewhat concerned about infection. During treatment, 73.1% reported no pain/discomfort with catheter, 73.1% no wound difficulty, 51.0% no pain during removal, and 71.2% no pain post-treatment. A total of 98.1% of patients rated the experience good/excellent, 90.4% reported no/minor side effects, 92.3% rated cosmesis good/excellent, 98.1% were very/extremely likely to choose MBT again, and 100% would recommend MBT.

CONCLUSIONS

QOL is high during/after MBT. More data are needed from ongoing trials to compare with WBRT.

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.

On-Board Imager-based MammoSite treatment verification

Contemporary radiation oncology departments are often lacking a conventional simulator due to common use of virtual simulation and recent implementation of image guided radiation therapy. A protocol based on MammoSite method was developed using CT based planning, a Source Position Simulator (SPS) with a Simulator Wire and a linear accelerator based On-Board Imager (OBI) for daily verification. After MammoSite balloon implantation, the patient undergoes a CT study. The images are evaluated for tissue conformance, balloon symmetry, and balloon surface to skin distance according to the departmental procedure. Prior to the CT study the SPS is attached to the transfer tube that in turn is attached to the balloon catheter. The length from the indexer to the first dwell position is measured using the simulator wire with X-ray markers. After the CT study is performed, the data set is sent to the Varian Eclipse treatment planning system (TPS) and to the Nucletron PLATO brachytherapy planning system. The reference digitally reconstructed radiographs (DRRs) of anterior and lateral setup fields are created using Eclipse TPS and are immediately available on the OBI console via the Varian Vision integrated system. The source dwell position coinciding with the balloon center is identified in the CT dataset, followed by the offset calculation, catheter reconstruction, dose points placement and dwell time calculation. OBI fluoroscopy images are acquired and marked as initial. Prior to each treatment fraction balloon diameter and symmetry are evaluated using OBI fluoroscopy and tools available on the OBI console. Acquired images are compared with reference DRRs and/or initial OBI images. The whole process from initial evaluation to daily verification is filmless and does not undermine the precision of the procedure. This verification time does not exceed 10 min. The balloon diameter correlates well (within 1 mm) between initial CT and OBI verification images. The balloon symmetry is defined with 1 mm accuracy using existing OBI console tools. It is feasible to use OBI based simulation for the MammoSite balloon placement evaluation, balloon integrity daily verification, and treatment dwell position coincidence with balloon center. This verification is a rapid process and is an alternative to the conventional simulator based technique. The simulator wire with X-ray markers for the SPS is the recommended tool for the CT based MammoSite procedure.

Target Volume Delineation for Partial Breast Radiotherapy Planning: Clinical Characteristics Associated with Low Interobserver Concordance

PURPOSE

To examine variability in target volume delineation for partial breast radiotherapy planning and evaluate characteristics associated with low interobserver concordance.

METHODS AND MATERIALS

Thirty patients who underwent planning CT for adjuvant breast radiotherapy formed the study cohort. Using a standardized scale to score seroma clarity and consensus contouring guidelines, three radiation oncologists independently graded seroma clarity and delineated seroma volumes for each case. Seroma geometric center coordinates, maximum diameters in three axes, and volumes were recorded. Conformity index (CI), the ratio of overlapping volume and encompassing delineated volume, was calculated for each case. Cases with CI </=0.50 were analyzed to identify features associated with low concordance.

RESULTS

The median time from surgery to CT was 42.5 days. For geometric center coordinates, variations from the mean were 0.5-1.1 mm and standard deviations (SDs) were 0.5-1.8 mm. For maximum seroma dimensions, variations from the mean and SDs were predominantly <5 mm, with the largest SDs observed in the medial-lateral axis. The mean CI was 0.61 (range, 0.27-0.84). Five cases had CI </=0.50. Conformity index was significantly associated with seroma clarity (p < 0.001) and seroma volume (p < 0.002). Features associated with reduced concordance included tissue stranding from the surgical cavity, proximity to muscle, dense breast parenchyma, and benign calcifications that may be mistaken for surgical clips.

CONCLUSION

Variability in seroma contouring occurred in three dimensions, with the largest variations in the medial-lateral axis. Awareness of clinical features associated with reduced concordance may be applied toward training staff and refining contouring guidelines for partial breast radiotherapy trials.

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.

Placement Technique and the Early Complications of Balloon Breast Brachytherapy

BACKGROUNDS AND OBJECTIVES

Open (OT) and percutaneous closed (PCT) techniques have been described for placement of the MammoSite catheter to deliver accelerated partial breast brachytherapy. We report early complications of both techniques.

METHODS

A total of 125 patients underwent catheter placement for MammoSite high-dose rate brachytherapy, with 108 patients successfully completing treatment. The OT was used in 85 patients and PCT in 40 patients. The mean distance between the balloon surface and breast skin was 1.44 cm and 1.31 cm, respectively. Average skin dose was 278 cGy in the OT group and 295 cGy in the PCT group (P > 0.05). Average gross specimen size was 43.16 cm3 in the OT group and 62.19 cm3 in the PCT group. Median follow-up was 11 months for the OT group and 5 months for the PCT group.

RESULTS

In 17 cases, the catheter was subsequently removed without the patient completing treatment. Two of the patients in the OT group (3%) developed a delayed abscess. The overall incidence of persistent seroma (>6 months) was 20% with all occurring in the OT group, 30% of those patients. There were no acute skin toxicities higher than grade 2. The overall cosmesis is excellent or good in 95% of patients.

CONCLUSION

Despite short follow-up and a small sample size in this study, it seems that the MammoSite brachytherapy was well tolerated by patients with early stage breast cancer when using either the OT or PCT.

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.

An ambiguous phenomenon of radiation and drugs: recall reactions

The term 'radiation recall' describes an acute inflammatory reaction in previously irradiated areas after the administration of certain inciting systemic agents. It was first described in 1959 by D'Angio that dermatitis is related to the application of actinomycin D on the skin. Though this reaction occurs frequently on the skin, it may also be seen in the oral mucosa, the larynx, esophagus, small intestine, lungs, muscle tissue, and brain. Most drugs associated with recall reactions are cytotoxics, however, several other drugs may also elicit the phenomenon. Although this phenomenon is well known, its etiology is not understood. Radiation recall reactions are generally associated with megavoltage radiotherapy. The time interval between the completion of radiotherapy and the recall reaction ranges from days to years. The recall reaction occurs on average 8 days (3 days to 2 months) after the application of the promoting agent. Although no standard treatment exists, some authors suggest discontinuation of the inciting drug and the use of corticosteroids or nonsteroidal anti-inflammatory agents.

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.

Feasibility study on the MammoSite in early-stage breast cancer: Initial experience

The aims of this study were to evaluate the feasibility, practicality, efficacy and safety of the delivery of accelerated partial breast irradiation using the MammoSite for the boost phase. Six patients aged 53-69 years with stage T1N0, T2N0, Grade I-II invasive ductal carcinoma received 9-10 Gy prescribed at 1 cm from the MammoSite balloon surface in two fractions of 4.5-5 Gy 6 h apart. The MammoSite was inserted 20-37 days postoperatively. External beam radiation therapy to the whole breast commenced 1-5 days after accelerated partial breast irradiation. The maximum skin dose ranged from 3 to 9 Gy. The skin-cavity distance ranged from 7 to 19 mm. Local discomfort resolved as the scar healed spontaneously within 3-5 days. No Grade III or higher acute toxicity or local infection was recorded. The ease of insertion and accuracy of dosimetry makes the MammoSite suitable for use in properly selected women with early-stage breast cancer in a trial setting.

Partial breast irradiation: Ready for routine?

Breast-conserving treatment is considered the standard therapy for most early-stage breast cancer and has given excellent results. That notwithstanding in the last years, several institutions are trying to revisit the adjuvant radiation treatment setting, especially with respect to possible changes in overall treatment time and target volume within the philosophy of modern partial breast irradiation. Up to date, no conclusive data are available on the possible role of partial breast irradiation in early-stage breast cancer but in this paper, we review the rationale and the researches currently being undertaken within the framework of this approach, trying to answer whether, in spite of the absence of the randomized evidence of the equivalence between whole and partial breast irradiation, could be already possible to suggest this treatment modality in the daily clinical practice, at least in some selected cases.

Breast interventions: a primer for interventional radiologists

Breast cancer is the second leading cause of cancer related deaths in the United States. The area of breast interventions has benefited from recent advances in devices and imaging quality. Ultrasound, MRI, and stereotactic guided vacuum assisted and mechanical rotating stick freeze biopsy are the preferred methods for histologic diagnosis of breast lesions. Ablation techniques are available for the treatment of benign and malignant breast disease. The MammoSite balloon catheter can be placed percutaneously for delivering high dose short term brachytherapy. Interventional Radiologists can and should perform all of these procedures to improve the quality of women's health.

Accelerated Partial Breast Irradiation Using the MammoSite Device: Early Technical Experience and Short-Term Clinical Follow-Up

The MammoSite brachytherapy system is a novel form of intracavitary accelerated partial breast irradiation (APBI) that allows treatment over a 5- to 7-day course after breast conserving surgery (BCS). Fifty-one patients with invasive breast carcinoma underwent BCS and APBI using the MammoSite device, with 30 (59%) patients having drain placement in the lumpectomy cavity. Main outcome measures included time to initiating APBI, cosmesis using the Harvard Scale, and local and distant tumor recurrence with short-term follow-up. Five (9.8%) devices were explanted because of unfavorable final pathological findings or infection. Mean time to the start of APBI in patients without drain placement was 7.2 days (range, 5–12 days) compared with 5.1 days (range, 3–8 days) in patients with drains (P = 0.003). Cosmetic results were excellent in 25 (54.3%) patients, good in 19 (41.3%) patients, and fair in 2 (4.4%) patients. With a mean follow-up of 16 months (range, 6–38 months), no ipsilateral breast recurrences developed in any of the 51 patients. Thirteen patients had at least a 2-year follow-up. Two patients developed brain metastases and died at 19 and 23 months, respectively. The favorable short-term outcomes support further studies comparing APBI with standard whole-breast irradiation in patients undergoing BCS.

Partial irradiation of the breast: Old challenges, new solutions

Breast-conserving treatment, characteristically consisting of surgical removal of the tumor and post-operative whole breast irradiation, is nowadays considered as the standard therapeutic approach for most women with stage I/II, invasive breast cancer. Recently, a number of institutions started investigating the feasibility and safety of novel approaches in radiotherapy, modulating concomitantly treatment time and irradiation volume. Whilst this strategy is still under investigation, recent clinical studies on accelerated partial breast irradiation with intra-operative radiotherapy or high conformality irradiation strongly suggest that the way patients with early breast cancer are irradiated should be revisited.

Dosimetric comparisons between high dose rate interstitial and MammoSite™ balloon brachytherapy for breast cancer

BACKGROUND AND PURPOSE

To make a quantitative dosimetric comparison between treatment plans of multicatheter-based interstitial brachytherapy (IB) and MammoSite brachytherapy (MSB) for breast cancer.

PATIENTS AND METHODS

Seventeen patients treated with IB and twenty-four with MSB were selected for the study. The irradiations for IB patients were planned using conventional two-film reconstruction technique. Following the implantation each patient was CT scanned, then the planning target volume (PTV) was retrospectively defined on the CT data set, and the original plan was reconstructed (CONV plans). Furthermore, conformal plans were also created by dose optimization on target (CONF plans). The planning for MammoSite applicator was based on CT imaging. The dose distributions were evaluated with dose-volume histograms. The following parameters were calculated and compared: volume of the PTV and its percentage receiving 90, 100, 150 and 200% of the prescribed dose (V90, V100, V150 and V200, respectively), percentage dose covering 90% of the PTV (D90), minimum dose in the PTV (D(min)), maximum dose in the PTV (D(max)) for MSB only, dose homogeneity index (DHI), and conformal index (COIN). To assess the dose to organs at risk maximum point dose to skin, lung and heart was used.

RESULTS

The median number of implanted catheters for IB was 11 (range: 6-13), the average balloon volume for MSB was 59.1cm(3) (range: 43.4-75.3 cm(3)). The average volume of PTV was 63.4 and 109.6 cm(3) for IB and MSB patients, respectively. The average V90, V100, V150, V200 were 76, 70, 26 and 9% for IB(CONV); 92, 87, 55 and 32% for IB(CONF) and 96, 88, 27 and 3% for MSB, respectively. The average D90 was 72, 94 and 99%, the D(min) was 47, 58 and 67%, respectively. The mean D(max) was 258% for MSB. The average DHI was 0.63, 0.37 and 0.70 for IB(CONV), IB(CONF) and MSB, respectively. D(max) to skin, lung and heart were 45, 54 and 31% for IB(CONV), 50, 55 and 29% for IB(CONF,) 97, 66 and 27% for MSB, respectively.

CONCLUSIONS

Target volume coverage was better for MSB than conventional IB, and it was comparable to conformal IB. The suboptimal coverage for IB patients is due to radiography based planning, which is unable to provide 3D information of the target. Dose homogeneity was somewhat better for MSB than IB(CONV), but the dose to skin and lung was higher for MSB. The MSB provides dosimetrically acceptable dose plans. The quality of interstitial implants can be improved with image-guided catheter insertions regarding both homogeneity and conformality.

Clinical experience with the MammoSite® radiation therapy system for brachytherapy of breast cancer: Results from an international phase II trial

BACKGROUND AND PURPOSE

In a prospective multi-center phase II trial, we investigated the MammoSite Radiation Therapy System, a new device for delivering intracavitary brachytherapy following breast conserving surgery. The MammoSite is a dual lumen, closed ended catheter with a small, spherical inflatable balloon and a port for connecting a remote afterloader to the central lumen. We analyzed the surgical procedure and placement of the MammoSite, treatment planning and radiation delivery complications and cosmesis, as well the comfort for the patients.

PATIENTS AND METHODS

Between 2002 and 2004 a total of 32 patients (pts) were implanted using the MammoSite. The reference isodose was defined 1cm from the balloon surface. We analyzed the post-implant anatomic position of the applicator and the geometric form of the balloon via ultrasound, CT and X-ray, related side effects, cosmetic outcome and patient quality of life.

RESULTS

Twenty-three out of 32 patients (72%) were eligible for MammoSite intracavitary brachytherapy. Twenty-eight percentage had to be excluded because of different reasons. Eleven patients were treated with primary brachytherapy with a total dose of 34 Gy (2 x 3.4 Gy) and 12 had a boost with a mean dose of 13.3 Gy (range: 7.5-15 Gy; 2 x 2.5 Gy) combined with EBRT and doses ranged between 46 and 50 Gy. In three cases a balloon rupture occurred. We observed two abscesses within 3 months of implantation and serious seroma development in 10 patients (39%). Skin related side effects were erythema in 21 patients (91%), hyperpigmentation in 13 patients (56%) and teleangiectasia in six patients (26%) after mean follow-up 20 months.

CONCLUSIONS

The MammoSite Radiation Therapy System is a feasible treatment modality for intracavitary brachytherapy of breast cancer after breast conserving surgery. The advantage of the system is only one applicator is necessary for the delivery of a fractionated radiotherapy. In addition, patient tolerance of the procedure is high. Critical issues concern possible overdosages at the skin reflected by a high rate of late skin damage after only 20 months of follow-up time. The method could serve as an alternative to conventional multi-catheter brachytherapy for a selected group of patients.

Early European experience with the MammoSite radiation therapy system for partial breast brachytherapy following breast conservation operation in low-risk breast cancer

Preliminary results of ultrasound studies do exist in the literature on the successful use of the MammoSite Radiation Therapy System (RTS), a new device for delivering brachytherapy following breast-conserving surgery. In Europe, some groups started a prospective multicentre trial to investigate the use of the MammoSite RTS. In this early publication, we analysed the surgical procedure and placement of the MammoSite, treatment planning and radiation delivery complications, and early cosmesis, as well as the comfort of the patients. Between June 2002 and March 2005, a total of 54 low-risk breast cancer patients fulfilling the enrolment criteria were implanted intra- or postoperatively using the MammoSite applicator. After inflating the balloon in the excision cavity, the reference isodose was defined 1cm from the balloon's surface. Twenty-eight patients were treated with primary brachytherapy with a total dose of 34 Gy (2x3.4 Gy) and 16 patients had a boost with a mean dose of 13.3 Gy (range: 7.5-15 Gy; 2x2.5 Gy) combined with external beam radiotherapy (EBRT). Doses ranged between 46 and 50 Gy. We analysed the postimplant anatomic position of the applicator in relation to the skin and chest wall as well as the geometric form of the balloon via ultrasound, computed tomography and X-ray before, during and after the treatment. Forty-four out of 54 patients (81.5%) were eligible for MammoSite RTS brachytherapy. Ten patients were excluded from the trial due to the strict study criteria and received no brachytherapy. Balloon rupture occurred in two cases. We observed seroma in 16 patients (36%); furthermore, an abscess developed in two patients (4.5%) within 3 months of implantation. Postoperative air gaps and haematoma were successfully reduced by draining the operation cavity in one institution. At a mean follow-up of 14 months (range 3-31 months), the skin-related side effects observed were skin discoloration or inflammation in 36 patients (82%) and teleangiectasia in eight patients (18%). The MammoSite RTS is a feasible treatment modality for postoperative partial breast irradiation after breast-conserving surgery for selected low-risk breast cancer patients. The main advantage of the system is the necessity of only one applicator for the delivery of fractionated radiotherapy over a 5-day treatment period. In addition, patient tolerance of the procedure is high. Based on this early experience, the method may serve as a successful alternative to conventional multicatheter brachytherapy for a highly select group of patients, but we have to bear in mind the higher level of acute toxicity.