Accelerated partial breast irradiation

Progress and controversies: radiation therapy for invasive breast cancer

Radiation therapy is a critical component of the multidisciplinary management of invasive breast cancer. In appropriately selected patients, radiation not only improves local control, sparing patients the morbidity and distress of local recurrence, but it also improves survival by preventing seeding and reseeding of distant metastases from persistent reservoirs of locoregional disease. In recent years, considerable progress has been made toward improving our ability to select patients most likely to benefit from radiotherapy and to administer treatment in ways that maximize clinical benefit while minimizing toxicity and burden. This article reviews the role of radiation therapy in invasive breast cancer management, both after breast-conserving surgery and after mastectomy. It focuses particularly on emerging evidence that helps to define the clinical situations in which radiotherapy is indicated, the appropriate targets of treatment, and optimal approaches for minimizing both the toxicity and the burden of treatment, all in the context of the evolving surgical and systemic management of this common disease. It includes a discussion of new approaches in breast cancer radiotherapy, including hypofractionation and intensity modulation, as well as a discussion of promising avenues for future research.

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.

On the feasibility of treating to a 1.5 cm PTV with a commercial single-entry hybrid applicator in APBI breast brachytherapy

Purpose

To evaluate and determine whether 30 patients previously treated with the SAVI™ device could have been treated to a PTV_EVAL created with a 1.5 cm expansion. This determination was based upon dosimetric parameters derived from current recommendations and dose-response data.

Material and methods

Thirty patients were retrospectively planned with PTV_EVALs generated with a 1.5 cm expansion (PTV_EVAL_1.5). Plans were evaluated based on PTV_EVAL_1.5 coverage (V90, V95, V100), skin and rib maximum doses (0.1 cc maximum dose as a percentage of prescription dose), as well as V150 and V200 for the PTV_EVAL_1.5. The treatment planning goal was to deliver ≥90% of the prescribed dose to ≥90% of the PTV_EVAL_1.5. Skin and rib maximum doses were to be ≤125% of the prescription dose and preferably ≤100% of the prescription dose. V150 and V200 were not allowed to exceed 52.5 cc and 21 cc, respectively. Plans not meeting the above criteria were recomputed with a 1.25 cm expanded PTV_EVAL and re-evaluated.

Results

Based on the above dose constraints, 30% (9/30) of the patients evaluated could have been treated with a 1.5 cm PTV_EVAL. The breakdown of cases successfully achieving the above dose constraints by applicator was: 0/4 (0%) 6-1, 6/15 (40%) 8-1, and 3/11 (27%) 10-1. For these PTV_EVAL_1.5 plans, median V90% was 90.3%, whereas the maximum skin and rib doses were all less than 115.2% and 117.6%, respectively. The median V150 and V200 volumes were 39.2 cc and 19.3, respectively. The treated PTV_EVAL_1.5 was greater in volume than the PTV_EVAL by 41.7 cc, and 60 cc for the 8-1, and 10-1 applicators, respectively. All remaining plans (17) successfully met the above dose constraints to be treated with a 1.25 cm PTV_EVAL (PTV_EVAL_1.25). For the PTV_EVAL_1.25 plans, V90% was 93.7%, and the maximum skin and rib doses were all less than 109.2% and 102.5%, respectively. The median V150 and V200 volumes were 41.2 cc and 19.3, respectively. The treated PTV_EVAL_1.25 was greater in volume than the PTV_EVAL by 16 cc, 24.9 cc, and 33.5 cc for the 6-1, 8-1 and 10-1 applicators, respectively.

Conclusions

It is dosimetrically possible to treat beyond the currently advised 1.0 cm expanded PTV_EVAL. Most patients should be able to be treated with a 1.25 cm PTV_EVAL and a select group with a 1.5 cm PTV_EVAL. Applicator size appears to determine the ability to expand to a 1.5 cm PTV_EVAL, as smaller devices were not as propitious in this regard. Further studies may identify additional patient groups that would benefit from this approach.

Ductal carcinoma in situ of the breast treated with accelerated partial breast irradiation using balloon-based brachytherapy

BACKGROUND

We reviewed our institution's experience treating patients with ductal carcinoma in situ (DCIS) of the breast with balloon-based accelerated partial breast irradiation (APBI) to determine the efficacy of this treatment approach in this group of patients.

MATERIALS AND METHODS

A total of 126 cases of DCIS seen and treated with APBI using balloon-based brachytherapy constitute the study population. The median age at diagnosis was 59 years (range, 37-82) with 21% younger than age 50. Nuclear grade distribution was 52.5, 41.4, and 6.1% high, intermediate and low, respectively. Of these patients, 86% had estrogen receptor positive DCIS. The median tumor size was 6 mm (range, 1-26). Margins of excision were negative in 98.4% of patients. All patients were treated with 34 Gy in 10 fractions using either the MammoSite™ or Contura™ breast brachytherapy catheter. A total of 87 patients (73.1%) were placed on adjuvant tamoxifen or arimedex.

RESULTS

With a median follow-up of 24 months (range, 0.7-73.9), three (2.4%) ipsilateral breast tumor recurrences (IBTRs) developed for a 2-year actuarial rate of 0.81%. Recurrences developed 4.8, 24.7, and 24.9 months after treatment. On univariate analysis, no variable was associated with IBTR. A subset analysis of the first 50 consecutive patients treated was also performed. With a median follow-up of 40 months (range, 15.6-73.9), one IBTR developed for a 3-year actuarial rate of 2.15%.

CONCLUSIONS

Early results in patients with DCIS treated with APBI using balloon-based brachytherapy produced results similar to those with invasive cancer treated with APBI or DCIS treated with whole breast irradiation.

Dosimetric Improvements in Balloon Based Brachytherapy Using the Contura® Multi-Lumen Balloon (MLB) Catheter to Deliver Accelerated Partial Breast Irradiation

Purpose

Preliminary dosimetric findings in patients managed with the Contura^® Multi-Lumen Balloon (MLB) breast brachytherapy catheter to deliver accelerated partial breast irradiation (APBI) on a multi-institutional phase IV registry trial were reviewed.

Material and methods

CT-based 3D planning with dose optimization was performed for all patients. For the study, new ideal dosimetric goals were developed: 1) ≥ 95% of the prescribed dose (PD) covering ≥ 90% of the target volume (TV), 2) a maximum skin dose ≤ 125% of the PD, 3) maximum rib dose ≤ 145% of the PD, and 4) the V150 ≤ 50 cc and V200 ≤ 10 cc. The frequency of concurrently achieving these dosimetric goals using the Contura^® MLB was investigated.

Results

194 cases were evaluable. Employing the MLB, all ideal dosimetric criteria were achieved in 76% of cases. Evaluating dosimetric criteria separately, 90% and 89% of cases met the new ideal skin and rib dose criteria, respectively. In 96%, ideal TV coverage goals were achieved and in 96%, dose homogeneity criteria (V150 and V200) were met. For skin spacing ≥ 5-7 mm, the median skin dose was 121% of the PD and when < 5 mm, the median skin dose was 124.4%. For rib distancees < 5 mm, the median rib dose was reduced to 136.4% of the PD. For skin spacing < 7 mm and distance to rib < 5 mm, the median skin and rib doses were concurrently limited to 121% and 142.8% of the PD, respectively.

Conclusions

The Contura^® MLB catheter provides potential improvements in dosimetric capabilities (i.e., reduced skin and rib doses and improved TV coverage) in many clinical scenarios.

Use of serial CT imaging for the quality assurance of MammoSite therapy

PURPOSE

As experience with the MammoSite device for accelerated partial breast irradiation (APBI) has increased, more centers are starting to use three-dimensional (3D) treatment planning to generate plans with multiple nonequally weighted dwell positions. This report presents the use of serial computed tomography (CT) imaging, in addition to planar or ultrasound imaging, for the quality assurance of an APBI treatment using the elliptical MammoSite.

METHODS AND MATERIALS

CT images of a patient implanted with a 4cmx6cm elliptical MammoSite balloon were acquired. A treatment plan using multiple, nonequally weighted dwells was generated and delivered on Day 1 of a 10-fraction, twice-daily treatment. Before morning treatments on Days 2-5, the patient was reimaged on CT. Treatment plans on repeat CTs were generated two ways: using the decay-corrected plan from Day 1 (unadapted) vs. modifying the plan to account for changes in implant geometry (adapted). Adapted and unadapted plans on repeat CTs were compared with one another, and to the Day 1 plan.

RESULTS

The use of unadapted plans led to increased doses to normal tissues, particularly the skin. Adaptive planning on the repeat CTs was effective for maintaining acceptable dosimetry throughout treatment.

CONCLUSIONS

Serial CT imaging was shown to provide a useful tool for the quality assurance of an elliptical balloon implant during the course of treatment. Serial CT imaging, as opposed to planar or ultrasound imaging, was necessary to evaluate skin dose and to facilitate adaptation of the treatment plan to satisfy limits for skin dose.

Initial radiation experience evaluating early tolerance and toxicities in patients undergoing accelerated partial breast irradiation using the Contura Multi-Lumen Balloon breast brachytherapy catheter

PURPOSE

We reviewed our institution's experience treating patients with the Contura Multi-Lumen Balloon (SenoRx, Inc., Irvine, CA) breast brachytherapy catheter to deliver accelerated partial breast irradiation.

METHODS AND MATERIALS

Forty-one patients treated with breast-conserving therapy received adjuvant radiation using the Contura catheter (34Gy in 3.4Gy fractions). Thirteen patients had Stage 0, 21 had Stage I, and 7 had Stage II breast cancer. Median followup was 8 months (range, 1-17).

RESULTS

Median, minimum skin spacing was 10mm (range, 2-17). Median, maximum skin doses (% of prescribed dose [PD]) were 99.7 (range, 57.1-124.1). Eight patients were treated with a skin spacing <or=5mm and 2 had a spacing of 2mm. Median, maximum rib doses were 102.6% of PD (10.0-187.7), and the median percentage of the planning target volume for evaluation (PTV_EVAL) receiving 95% of the PD was 98.8 (range, 79.4-107.4). The median volume receiving 200% of the PD was 5.7cc (range, 1.3-9.9). The percentage of patients with excellent/good cosmetic results at 6 months (n=15) and 12 months (n=12) was 100%. Patient tolerance was assessed on a scale 0-10 (0=no pain, 10=requiring narcotic analgesics). In 37 out of 38 patients, pain was graded <or=3 at the time of catheter insertion. Four breast infections (11%) and one transient symptomatic seroma (3%) developed.

CONCLUSION

Adjuvant accelerated partial breast irradiation using the Contura Multi-Lumen Balloon catheter exhibited similar toxicities to standard single lumen balloon brachytherapy with improvements in dosimetric capabilities (i.e., reduced skin and rib doses and improved PTV_EVAL coverage).

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.

Case report and dosimetric analysis of an axillary recurrence after partial breast irradiation with mammosite catheter

Partial breast irradiation (PBI) was designed in part to decrease overall treatment times associated with whole breast radiation therapy (WBRT). WBRT treats the entire breast and usually portions of the axilla. The goal of PBI is to treat a smaller volume of breast tissue in less time, focusing the dose around the lumpectomy cavity. The following is a case of a 64-year-old woman with early-stage breast cancer treated with PBI who failed regionally in the ipsilateral axilla. With our dosimetric analysis, we found that the entire area of this axillary failure would have likely received at least 45 Gy if WBRT had been used, enough to sterilize microscopic disease. With PBI, this area received a mean dose of only 2.8 Gy, which raises the possibility that this regional failure may have been prevented had WBRT been used instead of PBI.

Three-year analysis of treatment efficacy, cosmesis, and toxicity by the American Society of Breast Surgeons MammoSite Breast Brachytherapy Registry Trial in patients treated with accelerated partial breast irradiation (APBI)

BACKGROUND

This report presents 3 years of data on treatment efficacy, cosmetic results, and toxicities for patients enrolled on the American Society of Breast Surgeons MammoSite (Cytyc, Bedford, Mass) Breast Brachytherapy Registry Trial.

METHODS

A total of 1440 patients (1449 cases) with early stage breast cancer who were undergoing breast-conserving therapy were treated with the MammoSite device to deliver accelerated partial breast irradiation (APBI) (34 Gy in 3.4 Gy fractions). Of these, 1255 (87%) cases had invasive breast cancer (IBC; median size = 10 mm), and 194 (13%) cases had ductal carcinoma in situ (DCIS; median size = 8 mm). Median follow-up was 30.1 months.

RESULTS

Twenty-three (1.6%) cases developed an ipsilateral breast tumor recurrence (IBTR) for a 2-year actuarial rate of 1.04% (1.11% for IBC and 0.59% for DCIS). No variables were associated with IBTR. Six (0.4%) patients developed an axillary failure. The percentages of breasts with good to excellent cosmetic results at 12 (n = 980), 24 (n = 752), 36 (n = 403), and 48 months (n = 67 cases) were 95%, 94%, 93%, and 93%, respectively. Breast seromas were reported in 23.9% of cases (30% in open-cavity implants and 19% in closed-cavity implants). Symptomatic seromas occurred in 10.6% of cases, and 1.5% of cases 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 37.5 months, the 3-year actuarial rate of IBTR was 1.79%.

CONCLUSIONS

Treatment efficacy, cosmesis, and toxicity 3 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.

Clinical and dosimetric experience with MammoSite-based brachytherapy under the RTOG 0413 protocol

MammoSite balloon brachytherapy is a relatively new technique for partial breast irradiation. The present paper focuses on the treatment planning, dosimetry, and quality assurance aspects of that treatment, based on the Radiation Therapy Oncology Group 0413 randomized prospective trial (RTOG 0413) protocol. We investigate the usefulness of evaluating implants for treatment appropriateness according to the full set of RTOG criteria as compared with the manufacturer's guidelines. We describe our methods to improve MammoSite balloon implants that would otherwise not comply with the protocol. The initially acquired computed tomography (CT) images are evaluated for tissue conformance, balloon surface-to-skin distance, and balloon symmetry. If the implant fails to meet the foregoing criteria, corrective action such as delay in the CT scan, balloon manipulation, or fluid volume adjustment is taken, and the patient is re-scanned. If the corrective action appears to be successful, three dimensional treatment planning and dose-volume histogram analysis is performed to evaluate the geometric and dosimetric parameters with regard to the RTOG 0413 protocol. The evaluated parameters include, volume ratio of the lumpectomy cavity to the ipsilateral breast, target volume coverage, tissue-balloon conformance, balloon symmetry, minimal balloon surface-to-skin distance, maximum skin dose, and normal breast tissue dose-volume parameters V150 and V200. Among our implants, 21.7% did not initially meet the RTOG 0413 acceptance criteria. Asymmetry and poor conformance values reduce the target volume coverage, and so an implant with moderate conformance and asymmetry can be within the manufacturer's guidelines, but still not meet the RTOG criteria. Our intervention corrected all but one of the implants that failed to meet the criteria. Manipulating the cavity and adjusting the balloon volume may salvage an implant and meet the strict geometric and dosimetric criteria imposed by the RTOG 0413 protocol.

Patterns of Failure After MammoSite Brachytherapy Partial Breast Irradiation: A Detailed Analysis

PURPOSE

To report the results of a detailed analysis of treatment failures after MammoSite breast brachytherapy for partial breast irradiation from our single-institution experience.

METHODS AND MATERIALS

Between October 14, 2002 and October 23, 2006, 78 patients with early-stage breast cancer were treated with breast-conserving surgery and accelerated partial breast irradiation using the MammoSite brachytherapy applicator. We identified five treatment failures in the 70 patients with >6 months' follow-up. Pathologic data, breast imaging, and radiation treatment plans were reviewed. For in-breast failures more than 2 cm away from the original surgical bed, the doses delivered to the areas of recurrence by partial breast irradiation were calculated.

RESULTS

At a median follow-up time of 26.1 months, five treatment failures were identified. There were three in-breast failures more than 2 cm away from the original surgical bed, one failure directly adjacent to the original surgical bed, and one failure in the axilla with synchronous distant metastases. The crude failure rate was 7.1% (5 of 70), and the crude local failure rate was 5.7% (4 of 70). Estimated progression-free survival at 48 months was 89.8% (standard error = 4.5%).

CONCLUSIONS

Our case series of 70 patients with >6 months' follow-up and a median follow-up of 26 months is the largest single-institution report to date with detailed failure analysis associated with MammoSite brachytherapy. Our failure data emphasize the importance of patient selection when offering partial breast irradiation.

Analysis of Treatment Efficacy, Cosmesis, and Toxicity Using the MammoSite Breast Brachytherapy Catheter to Deliver Accelerated Partial-Breast Irradiation: The William Beaumont Hospital Experience

PURPOSE

To review our institution's experience of treating patients with the MammoSite (Cytyc Corp., Marlborough, MA) breast brachytherapy catheter to deliver accelerated partial-breast irradiation (APBI), for determining short-term treatment efficacy, cosmesis, and toxicity.

METHODS AND MATERIALS

From January 2000 to April 2006, 80 patients treated with breast-conserving therapy (BCT) received adjuvant radiation using the MammoSite (34 Gy in 3.4-Gy fractions prescribed to 1.0 cm from the balloon surface). Twenty-three patients (29%) had Stage 0 breast cancer, 46 (57%) had Stage I breast cancer, and 11 (14%) had Stage II breast cancer. The median follow-up was 22.1 months.

RESULTS

Two ipsilateral breast-tumor recurrences (IBTRs) (2.5%) developed for a 3-year actuarial rate of 2.9% (no regional failures were observed). On molecular-based clonality assay evaluation, both recurrences were clonally related. Younger age at diagnosis was the only variable associated with IBTR (continuous variable, p = 0.044; categorical variable [<55 years vs. >/=55 years], p = 0.012). The percentages of patients with good/excellent cosmetic results at 12 and 36 months were 96.9% and 88.2%, respectively (p = NS). Patients with applicator-to-skin spacing <7 mm and those who received adjuvant systemic chemotherapy exhibited lower rates of good/excellent cosmetic results, though the association was not statistically significant. The overall incidence of symptomatic seromas and any seromas was 10% and 45%, respectively. The overall incidence of fat necrosis and infections was 8.8% and 11.3%, respectively.

CONCLUSIONS

Early-stage breast-cancer patients treated with adjuvant APBI using the MammoSite catheter exhibited a 3-year treatment efficacy, cosmesis, and toxicity similar to those observed with other forms of interstitial APBI at this length of follow-up.

A multidisciplinary approach to the management of breast cancer, part 2: therapeutic considerations

New approaches to breast cancer treatment have enhanced clinical outcomes and patient care. These approaches include advances in breast irradiation and hormonal and systemic adjuvant therapies. In addition to the identification of new drug targets and targeted therapeutics (eg, trastuzumab), there is renewed re-emphasis in the development of biomarkers for the prediction of response to therapy. One example is the pharmacogenetics of tamoxifen metabolism and the individualization of hormonal therapy. The current treatment of breast cancer continues to evolve rapidly, with new scientific and clinical achievements constantly changing the standard of care and leading to substantial reductions in breast cancer mortality. The goal of this article is to provide clinicians who care for women with breast cancer a multidisciplinary, state-of-the art approach to the treatment of these patients.

Breast skin doses from brachytherapy using MammoSite HDR, intensity modulated radiation therapy, and tangential fields techniques

Skin doses from brachytherapy using MammoSite HDR, Intensity Modulated Radiation Therapy (IMRT), and conventional tangential fields techniques were compared. For each treatment technique, skin doses were measured using paired thermoluminescent dosimeters placed on the patient's skin: (i) directly above the balloon catheter during MammoSite HDR brachytherapy treatments and (ii) 4 cm inside the treatment borders during the IMRT and conventional breast treatments. The mean dose measured was about 58% of the prescription dose for the patients treated using the MammoSite technique. On the other hand, for patients treated with IMRT and tangential fields, the mean dose was found to be about 69% and 71% of the corresponding prescription dose. This study suggests that in breast cancer radiation treatments the MammoSite HDR technique reduces skin doses compared to IMRT and tangential field techniques.

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.

The emergence of advanced brachytherapy techniques for common malignancies

The recent advent and integration of sophisticated radiation planning and imaging modalities has improved the quality of brachytherapy treatments, allowing for more conformal radiation delivery. Further investigation and follow-up are necessary to demonstrate improvements in outcome and morbidity with these refined approaches.

A pilot study of wider use of accelerated partial breast irradiation: intraoperative margin-directed re-excision combined with sole high-dose-rate interstitial brachytherapy

BACKGROUND

Accelerated partial breast irradiation (APBI) is generally limited to patients at extremely low risk of local recurrence. The significance of the risk factors, however, depends on the extent of surgery, radiation, and systemic therapy. In Japan, wide excision is generally supplemented by intraoperative margin-directed re-excision if the frozen section examination yields positive results. This approach combined with conventional radiotherapy achieved an excellent 10-year local control rate of 93%, and young age and ductal carcinoma in situ were not risk factors for local recurrence. To reduce the treatment duration, high-dose-rate interstitial brachytherapy (HDRIB) was employed. The first APBI phase I / II trial in Japan was conducted to determine if wider indications for early breast cancer patients were appropriate.

METHODS

The subjects comprised 20 patients including those with extensive intraductal component (n=7), ductal carcinoma in situ (n=2), positive final margins (n=3), and of younger age (< or = 45 years; n=5). Breast-conserving surgery using an intraoperative re-excision approach was followed by intraoperative implantation of applicators. Sole HDRIB of a 36-42 Gy in 6-7 fractions was delivered postoperatively over 3-4 days. Tumors were staged as follows: cT1 (n=12), cT2 (n=8), cN0 (n=20). Systemic therapy was used in 16 patients (80%). The median follow-up period was 52 months (range, 26-86 months).

RESULTS

Te five-year crude local, distant control, and Kaplan-Meier cause-specific survival rates were 95%, 95%, and 89%, respectively. Fat necrosis developed in 1 patient.

CONCLUSIONS

Sole HDRIB with intraoperative margin-directed re-excision was feasible under wider indications compared to other contemporary APBI series, and achieved acceptable and similar results to these series in terms of the local control rate and complications.

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.

Phase II trial of brachytherapy alone after lumpectomy for select breast cancer: toxicity analysis of RTOG 95-17

PURPOSE

Accelerated partial breast irradiation (APBI) can be delivered with brachytherapy within 4-5 days compared with 5-6 weeks for conventional whole breast external beam radiotherapy. Radiation Therapy Oncology Group 95-17 is the first prospective phase I-II cooperative group trial of APBI alone after lumpectomy in select patients with breast cancer. The toxicity rates are reported for low-dose-rate (LDR) and high-dose-rate (HDR) APBI on this trial.

METHODS AND MATERIALS

The inclusion criteria for this study included invasive nonlobular tumors < or =3 cm after lumpectomy with negative surgical margins and axillary dissection with zero to three positive axillary nodes without extracapsular extension. The patients were treated with either LDR APBI (45 Gy in 3.5-5 days) or HDR APBI (34 Gy in 10 twice-daily fractions within 5 days). Chemotherapy (> or =2 weeks after APBI) and/or tamoxifen could be given at the discretion of the treating physicians.

RESULTS

Between August 1997 and March 2000, 100 women were enrolled in this study, and 99 were evaluated. Of the 99 women, 33 were treated with LDR and 66 with HDR APBI. The median follow-up for all patients was 2.7 years (range, 0.6-4.4 years) and was 2.9 years for LDR and 2.7 years for HDR patients. Toxicities attributed to APBI included erythema, edema, tenderness, pain, and infection. Of the 66 patients treated with HDR APBI, 2 (3%) had Grade 3 or 4 toxicity. Of the 33 patients treated with LDR, 3 (9%) had Grade 3 or 4 toxicity during brachytherapy. Late toxicities included skin thickening, fibrosis, breast tenderness, and telangiectasias. No patient experienced late Grade 4 toxicity; the rate of Grade 3 toxicity was 18% for the LDR and 4% for the HDR groups.

CONCLUSION

Acute and late toxicity for this invasive breast radiation technique was modest and acceptable. Patients receiving chemotherapy, a nonprotocol therapy, had a greater rate of Grade 3 toxicity. The study design did not allow for this to be tested statistically.

A phase I/II trial to evaluate three-dimensional conformal radiation therapy confined to the region of the lumpectomy cavity for stage I/II breast carcinoma: Initial report of feasibility and reproducibility of Radiation Therapy Oncology Group (RTOG) Study 0319

BACKGROUND

This prospective study (Radiation Therapy Oncology Group Study 0319) examines the use of three-dimensional conformal external beam radiation therapy to deliver accelerated partial breast irradiation. Reproducibility, as measured by technical feasibility, was the primary end point with the goal of demonstrating whether the technique is widely applicable in a multicenter setting before a Phase III trial is undertaken.

METHODS AND MATERIALS

This study was designed such that if fewer than 5 cases out of the first 42 patients evaluable were scored as unacceptable, the treatment would be considered reproducible. Patients received 38.5 Gy in 3.85 Gy/fraction delivered twice daily. The clinical target volume included the lumpectomy cavity plus a 10-15-mm margin bounded by 5 mm within the skin surface and the lung-chest wall interface. The planning target volume (PTV) included the clinical target volume plus a 10-mm margin. Treatment plans were judged as follows: (1) No variations (total coverage), 95% isodose surface covers 100% of the PTV and all specified critical normal tissue dose-volume histogram (DVH) limits met. (2) Minor variation (marginal coverage), 95% isodose surface covers between > or = 95% and <100% of the PTV. No portion of PTV receives <93% of prescription (isocenter) dose. All specified critical normal tissue DVH limits fall within 5% of the guidelines. (3) Major variation (miss), 95% isodose surface covers <95% of the PTV. Portion of PTV receives <93% of prescription isocenter dose. Any critical normal tissue DVH limit exceeds 5% of the specified value.

RESULTS

A total of 58 patients were enrolled on this study between 8/15/03 and 4/30/04, 5 of whom were ineligible or did not receive protocol treatment. Two additional patients were excluded, one because the on-study form was not submitted, and the other because no treatment planning material was submitted. This primary end point analysis is based on the first 42 (out of 51) evaluable patients, which were accrued from 17 different institutions (31 centers were credentialed for case enrollment, but because of rapid accrual, not all centers were able to submit cases before trial closure). These 42 patients had the following characteristics: median age was 61 years; 48% had a maximum tumor dimension of <1 cm; 86% had invasive ductal carcinoma; 64% were postmenopausal; the location of tumor was upper outer for 40% and upper central for 21%; 79% had no chemotherapy, and 64% had no hormonal therapy. There were 4 cases with major variations (all 4 related to normal tissue DVHs exceeding 5% of the specified limit). A total of 32 cases with minor variations in treatment plans were detected (16 related to normal tissue DVHs exceeding the specified limits [by < or = 5%], 6 related to suboptimal coverage of the PTV, and 10 related to both). There were 6 cases with no variations. Of the 51 total evaluable patients, 1 additional major variation was noted (PTV receiving <93% of the prescription dose). An additional 5 cases with minor variations in treatment plans were detected (3 related to normal tissue DVHs exceeding the specified limits [by < or = 5%], 1 related to suboptimal coverage of the PTV, and 1 related to both). There were 3 more cases with no variations.

CONCLUSION

Accelerated partial breast irradiation using three-dimensional conformal external beam radiation therapy was shown in this preliminary analysis of the first 42 evaluable patients to be technically feasible and reproducible in a multi-institutional trial using exceptionally strict dosimetric criteria.

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.

First analysis of patient demographics, technical reproducibility, cosmesis, and early toxicity

BACKGROUND

Eighty-seven institutions participated in a Registry Trial that was designed to collect data on the clinical use of the MammoSite breast brachytherapy catheter for delivering breast irradiation. Patient demographics, technical reproducibility, cosmesis, and early toxicity were evaluated.

METHODS

From May 4, 2002 through July 30, 2004, 1419 patients with Stage 0, I, or II breast carcinoma who were undergoing breast-conserving therapy were enrolled on the trial. The device was placed in 1403 of these patients. The 1237 patients (87% of enrolled patients) who received accelerated partial breast irradiation (APBI) (34 grays prescribed to 1.0 cm in 10 fractions; 95% of patients who received APBI) constituted the study population; 86% of those patients (1068) had Stages I-II breast carcinoma (median tumor size, 10 mm), and 14% of those patients (169) had Stage 0 breast carcinoma. Ninety-one percent of the patients with invasive carcinoma (977 of 1068 patients) had negative lymph node status, and 99% of all patients had negative margins. The median patient age was 65 years. Systemic chemotherapy alone was administered to 79 patients with invasive carcinoma (7%), hormone therapy was administered to 501 patients (45%), and both were administered to 39 patients (4%). The median follow-up was 5 months.

RESULTS

Five hundred fifty-four catheters (45%) were placed with an open cavity at the time of lumpectomy, and 683 catheters (55%) were placed with a closed cavity after lumpectomy. Skin spacing ranged from 2 mm to 75 mm (median, 10 mm). In 89% of patients, there was a minimum balloon-to-skin distance of 7 mm (2% of patients had distances < 5 mm). In terms of cosmetic assessment, 95% of patients (1030 of 1084 patients) who had a cosmetic assessment had a good/excellent result (last follow-up visit). Cosmetic results at 12 months were good/excellent in 92% of 248 evaluable patients. The median skin spacing (> or = 7 mm vs. < 7 mm) was associated significantly with a good/excellent cosmetic result (96.1% vs. 86.8%; P = 0.0001) overall and at 6 months (P = 0.006). Increasing skin spacing was associated with a good/excellent cosmetic result as a continuous variable (P < 0.0001). In total, 92 of 1140 evaluable patients (8.1%) developed an infection in the breast, which was device-related in 5.3% of patients (60 of 1140 patients). Good/excellent cosmetic results were noted in 86% of these patients (last follow-up visit). Fifteen of 442 evaluable patients (3.4%) developed a radiation recall reaction. Good/excellent cosmetic results were noted in 93% of these patients at their last follow-up visit. One local recurrence (0.1%) was reported (new primary carcinoma).

CONCLUSIONS

Clinical evaluation of the ability of the MammoSite breast brachytherapy catheter to deliver APBI demonstrated acceptable technical reproducibility between multiple institutions and use in appropriate groups of patients. Cosmetic results at 12 months (92% good/excellent) were comparable to those reported with whole-breast RT. Early toxicity rates (infections, radiation recall) appeared to be acceptable.

The MammoSite breast brachytherapy applicator: a review of technique and outcomes

The MammoSite breast brachytherapy device was designed to overcome the potential scheduling problems associated with external beam radiotherapy (EBRT) and the technical difficulties of multi-catheter-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 (PBI) patient selection guidelines. The MammoSite applicator has been shown in two dosimetric studies to treat a comparable volume to multicatheter-based interstitial implants. The MammoSite catheter can be placed at the time of lumpectomy or in a separate procedure using ultrasound guidance. Four optimization methods have been described: the single point method, the six prescription point method (RUSH Technique), the University of Southern California Norris Cancer Center Method, and the Surface Optimization Technique. An excellent or good cosmetic outcome has been reported in 80% to 93% of patients at 1 year in most studies. Cosmetic results appear highly related to skin spacing. The MammoSite applicator has been associated with early side effects comparable with traditional breast conserving therapy. A NSABP trial will randomize patients to either whole breast irradiation or PBI consisting of interstitial brachytherapy, MammoSite brachytherapy, or 3D conformal radiation.

Surface optimization technique for MammoSite breast brachytherapy applicator

PURPOSE

We present a technique to optimize the dwell times and positions of a high-dose-rate (192)Ir source using the MammoSite breast brachytherapy applicator. The surface optimization method used multiple dwell positions and optimization points to conform the 100% isodose line to the surface of the planning target volume (PTV).

METHODS AND MATERIALS

The study population consisted of 20 patients treated using the MammoSite device between October 2002 and February 2004. Treatment was delivered in 10 fractions of 3.4 Gy/fraction, twice daily, with a minimum of 6 h between fractions. The treatment of each patient was planned using three optimization techniques. The dosimetric characteristics of the single-point, six-point, and surface optimization techniques were compared.

RESULTS

The surface optimization technique increased the PTV coverage compared with the single- and six-point methods (mean percentage of PTV receiving 100% of the prescription dose was 94%, 85%, and 91%, respectively). The surface method, single-point, and six-point method had a mean dose homogeneity index of 0.62, 0.68, and 0.63 and a mean full width at half maximum value of 189, 190, and 192 cGy/fraction, respectively.

CONCLUSION

The surface technique provided greater coverage of the PTV than did the single- and six-point methods. Using the FWHM method, the surface, single-, and six-point techniques resulted in equivalent dose homogeneity.

Dose perturbations due to contrast medium and air in MammoSite® treatment: An experimental and Monte Carlo study

In the management of early breast cancer, a partial breast irradiation technique called MammoSite (Proxima Therapeutic Inc., Alpharetta, GA) has been advocated in recent years. In MammoSite, a balloon implanted at the surgical cavity during tumor excision is filled with a radio-opaque solution, and radiation is delivered via a high dose rate brachytherapy source situated at the center of the balloon. Frequently air may be introduced during placement of the balloon and/or injection of the contrast solution into the balloon. The purpose of this work is to quantify as well as to understand dose perturbations due to the presence of a high-Z contrast medium and/or an air bubble with measurements and Monte Carlo calculations. In addition, the measured dose distribution is compared with that obtained from a commercial treatment planning system (Nucletron PLATO system). For a balloon diameter of 42 mm, the dose variation as a function of distance from the balloon surface is measured for various concentrations of a radio-opaque solution (in the range 5%-25% by volume) with a small volume parallel plate ion chamber and a micro-diode detector placed perpendicular to the balloon axis. Monte Carlo simulations are performed to provide a basic understanding of the interaction mechanism and the magnitude of dose perturbation at the interface near balloon surface. Our results show that the radio-opaque concentration produces dose perturbation up to 6%. The dose perturbation occurs mostly within the distances <1 mm from the balloon surface. The Plato system that does not include heterogeneity correction may be sufficient for dose planning at distances > or = 10 mm from the balloon surface for the iodine concentrations used in the MammoSite procedures. The dose enhancement effect near the balloon surface (<1 mm) due to the higher iodine concentration is not correctly predicted by the Plato system. The dose near the balloon surface may be increased by 0.5% per cm3 of air. Monte Carlo simulation suggests that the interface effect (enhanced dose near surface) is primarily due to Compton electrons of short range (<0.5 mm). For more accurate dosimetry in MammoSite delivery, the dose perturbation due to the presence of a radio-opaque contrast medium and air bubbles should be considered in a brachytherapy planning system.

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

For women undergoing breast-conserving surgery, recent reports suggest that in selected cases accelerated partial breast irradiation may yield results equal to that of whole breast irradiation. Over 31 months, 19 patients underwent accelerated partial breast irradiation using the MammoSite as the sole radiation treatment following breast-conserving surgery. Seventeen patients had the MammoSite inserted postoperatively using the scar entry technique (SET). Treatments were delivered using high dose rate iridium 192 given twice a day for 5 days. Three complications (two minor, one major) occurred. Late radiation morbidity and overall cosmetic results were evaluated. Eighty percent of patients had either no change from baseline or slight change in skin pigment. More than 90% had good or excellent overall cosmetic outcomes. Patients undergoing accelerated partial breast irradiation with the MammoSite inserted using SET had excellent overall cosmetic results. Advantages of the SET over intraoperative placement are presented.

Accelerated partial breast irradiation: the case for current use

The treatment of early stage breast cancer is evolving from traditional breast conservation techniques, employing conventionally fractionated whole breast irradiation, to techniques in which partial breast irradiation is used in an accelerated fractionation scheme. A growing body of evidence exists, including favorable findings. Additional studies are under way that may ultimately prove equivalence. The logic behind this approach is reviewed, and the currently available data are presented to support the current use of carefully applied partial breast irradiation techniques in appropriately selected and informed patients.

The MammoSite balloon brachytherapy catheter for accelerated partial breast irradiation

Whole-breast irradiation after lumpectomy for early-stage breast cancer appears to prevent relapse only at the site of initial involvement, and therefore it is likely that radiation can safely be limited to tissues immediately surrounding the excision cavity. Accelerated partial-breast irradiation (APBI) with the MammoSite catheter (Proxima Therapeutics, Alpharetta, GA) has been proposed as a means through which APBI can be offered to a wide range of patients. Although sufficient follow-up is not yet available regarding local control, survival, late toxicity, and long-term cosmetic results, early results are promising. This article reviews the current literature reflecting treatment, dose optimization, outcomes, and toxicity of APBI with the MammoSite brachytherapy catheter.

High dose rate brachytherapy: its clinical applications and treatment guidelines

Brachytherapy has the advantage of delivering a high dose to the tumor while sparing the surrounding normal tissues. With proper case selection and delivery technique, high-dose-rate (HDR) brachytherapy has great promise, because it eliminates radiation exposure, allows short treatment times, and can be performed on an outpatient basis. Additionally, use of a single-stepping source, allows optimization of dose distribution by varying the dwell time at each dwell position. However, when HDR brachytherapy is used, the treatments must be executed carefully, because the short treatment times do not allow any time for correction of errors, and mistakes can result in harm to patients. Hence, it is very important that all personnel involved in HDR brachytherapy be well trained and be constantly alert. It is expected that the use of HDR brachytherapy will greatly expand over the next decade and that refinements will occur primarily in the integration of imaging (computed tomography, magnetic resonance imaging, intraoperative ultrasonography) and optimization of dose distribution. It is anticipated that better tumor localization and normal tissue definition will help to optimize dose distribution to the tumor and reduce normal tissue exposure. The development of well-controlled randomized trials addressing issues of efficacy, toxicity, quality of life, and costs-versus-benefits will ultimately define the role of HDR brachytherapy in the therapeutic armamentarium.

Chest wall dose in MammoSite™ breast brachytherapy: Radiobiologic estimations of late complication risk based on dose–volume considerations

PURPOSE

To estimate the risk of late effects in women treated with MammoSite brachytherapy (MBT), the balloon catheters of which were placed near the ribs.

METHODS AND MATERIALS

Upon reviewing 93 plans, 16 patients (17%) treated with MBT were considered to have received a high chest wall dose (>or=120% isodose line in contact with a rib). A dose-volume histogram was generated for this rib, and its distance from the MBT balloon measured. Using the linear quadratic equation, the equivalent dose, delivered in 10 fractions, to the dose that causes a 5% and 50% risk of rib late effects at 5 years using 2Gy per fraction, was calculated to be 37 and 44Gy, respectively. The rib volume receiving greater than or equal to these doses (V37 and V44) was correlated to the balloon-to-rib distance. Chest wall signs, symptoms, and radiologic findings for all 16 patients were recorded.

RESULTS

The median balloon-to-rib distance was 4.8mm. The median values of V37 and V44 were 13.5% and 3.3%, respectively. All patients with a V37>or=15% and V44>or=5% had a minimum balloon-to-rib distance of <5mm. Two patients reported treatment-related chest wall tenderness (both had balloons placed <5mm from the chest wall), but neither presented with radiologic complications.

CONCLUSIONS

Sixteen patients considered to receive relatively high chest wall doses had less than one-third of their primary rib volume being exposed to the estimated TD 5/5 and TD 50/5 doses. Therefore, we estimate the risk of late effects in women treated with MBT, the balloon catheters of which placed near the ribs were negligible, and believe that MBT remains a safe and effective treatment for selected patients with early stage breast cancer.

MammoSite excision volume as a predictor for residual disease

BACKGROUND

The MammoSite catheter is a brachytherapy device used for accelerated partial breast irradiation. Currently, it is available as 2 spherically shaped balloons meant to fill 70-cc and 120-cc cavity volumes. This study was designed to define the relation of these excision volumes to the likelihood of microscopically detectable, residual disease based on tumor size, margin status, patient age, and histology.

METHODS

The study data base was comprised of 531 patients with Stage 0, I, and II breast carcinoma (using American Joint Committee on Cancer staging criteria) who received breast-conserving therapy and underwent surgical reexcision. Patients in the data base were stratified based on the volume of their initial excision: < or = 70 cc versus > 70 cc and < or = 120 cc versus > 120 cc.

RESULTS

Surgical margin size was found to be a strong predictor of residual disease both for patients with smaller excision volumes (P = 0.0014) and patients with larger excision volumes (P = 0.0003); histology (extensive intraductal component [EIC] or pure ductal carcinoma in situ [DCIS]) also was a strong predictor. Tumor size was significant only for the larger volume group (P = 0.029). On multivariate analysis, only histology and initial margin status were significant correlates with residual disease. The adjusted odds ratio for residual disease with pure DCIS was 0.79, and the adjusted odds ratio for invasive ductal or lobular carcinoma (IDC/ILC) without EIC was 0.44 relative to IDC/ILC with EIC (P = 0.008). The adjusted odds ratio for residual disease with a positive initial margin versus a negative initial margin was 2.65 (P < or = 0.0001).

CONCLUSIONS

For excisions amenable to use of the MammoSite catheter, a margin > or = 1.0 mm appeared to afford at most a 35% risk of microscopically detectable residual tumor. Evidence of EIC on excision of IDC/ILC connoted a significantly higher risk. Age did not appear to be predictive for residual disease.

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

PURPOSE

To report the acute complications incurred by the initial 37 patients who underwent accelerated partial breast irradiation with the MammoSite balloon breast brachytherapy applicator at the Medical University of South Carolina.

METHODS AND MATERIALS

Between May 2002 and March 2003, 37 patients with ductal carcinoma in situ or invasive carcinoma had MammoSite brachytherapy catheters successfully place after lumpectomy by one of four surgeons and were deemed eligible for high-dose-rate brachytherapy. An open technique was used in 32 implants and the scar entry technique was used in 5 implants. Patients had Stage pTis-pT2N1 with negative margins. A dose of 34 Gy was prescribed to 1 cm from the balloon surface using (192)Ir high-dose-rate brachytherapy and was delivered in 10 fractions twice daily. CT was used to confirm that the balloon surface was adherent to the lumpectomy cavity and to measure the balloon surface to skin surface distance. CT images and daily fluoroscopic simulations were used for treatment planning. Patients were assessed for acute toxicity on the day of therapy completion and 4 weeks after therapy by the radiation oncologist. In addition, all available data from radiation, surgical, and medical oncology were retrospectively reviewed for documentation of complications. All patients in this series had a minimal follow-up of 3 months; the mean follow-up for all patients was 7 months.

RESULTS

The acute complications were categorized as operative wound complications, infections, skin toxicity, seromas, or catheter failures. Operative wound complications occurred in 3 patients (8%). Radiation Therapy Oncology Group Grade 2 and Grade 3 toxicity occurred in 2 (5.4%) and 1 (2.7%) patient, respectively. Six (16.2%) developed wound infections and 12 (32.4%) seromas. Catheter failures due to leak occurred in 2 patients (5.4%) and rupture in 3 (8%).

CONCLUSION

The types of complications in this experience were similar to those in the Phase I trial of the MammoSite brachytherapy applicator. However, catheter failure due to leak occurred in our experience and was not described in the Phase I trial. The incidence of complications was greater in our series than in the Phase I trial; however, differences in toxicity scoring and the length of follow-up between the two series impeded direct comparisons. The incidences of complications over time reflect the steep learning curve for accelerated partial breast irradiation using the MammoSite brachytherapy applicator. Finally, radiation recall dermatitis developed in 1 patient treated after this review was completed.

High-dose-rate brachytherapy alone versus whole breast radiotherapy with or without tumor bed boost after breast-conserving surgery: Seven-year results of a comparative study

PURPOSE

To report the 7-year results of a prospective study of accelerated partial breast irradiation (APBI) using interstitial high-dose-rate brachytherapy and compare the treatment results with those achieved by standard, whole breast radiotherapy (WBRT), with or without a tumor bed boost (TBB).

METHODS AND MATERIALS

Between 1996 and 1998, 45 prospectively selected patients with T1N0-N1mi (single nodal micrometastasis), nonlobular breast cancer without the presence of an extensive intraductal component and with negative surgical margins were treated with APBI using interstitial high-dose-rate implants. A total dose of 30.3 Gy (n = 8) and 36.4 Gy (n = 37) in seven fractions within 4 days was delivered to the tumor bed plus a 1-2-cm margin. During the same period, 80 patients, who met the eligibility criteria for APBI but who were treated with 50 Gy WBRT with (n = 36) or without (n = 44) a 10-16-Gy TBB, were selected as controls. The median follow-up for the APBI and control groups was 81 and 83 months, respectively. Local control, relapse-free survival, cancer-specific survival, late side effects, and cosmetic results were assessed.

RESULTS

The crude rate of total ipsilateral breast failure was 6.7% (3 of 45), 11.4% (5 of 44), and 8.3% (3 of 36) for patients treated with APBI, WBRT, and WBRT + TBB, respectively. The differences in the 5- and 7-year actuarial rates of ipsilateral breast recurrence were not statistically significant among patients treated with APBI (4.4% and 9.0%), WBRT (4.7% and 14.8%), and WBRT + TBB (5.7% and 9.5%). No statistically significant difference in either the 7-year probability of relapse-free survival (79.8%, 73.5%, and 77.7% for APBI, WBRT, and WBRT + TBB, respectively) or cancer-specific survival (93.3%, 92.9%, and 93.9% for APBI, WBRT, and WBRT + TBB, respectively) was found. The 7-year actuarial elsewhere breast failure rate was 9.0% in the APBI group and 8.3% in the control group (p = 0.80). The rate of excellent/good cosmetic results was 84.4% in the APBI group and 68.3% in the control group (p = 0.04). The corresponding rates of asymptomatic fat necrosis were 20.0% and 20.6%. Symptomatic fat necrosis occurred in 1 patient (2.2%) treated with APBI. The incidence of Grade 2 or worse late radiation side effects was similar for both groups (26.7% vs. 28.6%).

CONCLUSION

Accelerated partial breast irradiation using interstitial high-dose-rate implants, with proper patient selection and quality assurance, yields similar 7-year results to those achieved with standard breast-conserving therapy. APBI does not increase the risk of elsewhere breast failures.

Acute Toxicity of High-Dose-Rate Intracavitary Brachytherapy With the MammoSite Applicator in Patients With Early-Stage Breast Cancer

BACKGROUND

Intracavitary brachytherapy with the MammoSite applicator as the sole radiation treatment in breast-conserving therapy is an option for women with early-stage breast cancer; we evaluated the acute toxicities associated with this treatment method.

METHODS

Thirty-one patients with 32 stage I or II breast carcinomas underwent breast-conserving therapy, which included lumpectomy with negative margins, sentinel node biopsy, or axillary dissection, followed by brachytherapy with the MammoSite applicator. Acute radiation skin complications were graded on the day of radiotherapy completion and at weeks 2, 4, 6, and 12 after radiation treatment. Cosmesis was graded on the Harvard Scale at all follow-ups.

RESULTS

The median follow-up was 11 months (range, 4-15 months). Twenty-seven of the 31 patients were treated with the device as the sole method of radiotherapy. No acute toxicities occurred during the 5 days of treatment. Nineteen patients (68%) had no to mild acute skin reactions, and 25% developed bright erythema and patchy moist desquamation. Two patients (7%) developed confluent moist desquamation within the first 4 weeks (grade 3); this healed by week 12. All skin reactions were localized to the area overlying the balloon. Sixteen percent (5 of 32) of all breasts with implants developed infection. Cosmesis was good to excellent in 86% of cases.

CONCLUSIONS

Most acute skin toxicities were mild. Our infection rate was higher than in prior studies that used interstitial brachytherapy. Cosmesis was good to excellent in most patients. Breast brachytherapy with the MammoSite catheter was well tolerated; further investigations of breast brachytherapy with this system are warranted.

MammoSite and interstitial brachytherapy for accelerated partial breast irradiation

BACKGROUND

In interstitial brachytherapy (IB), cosmesis and toxicity correlate with volume of tissue irradiated, dose homogeneity index (DHI), and adjuvant doxorubicin/cyclophosphamide based chemotherapy (ACCT). MammoSite brachytherapy (MSB) irradiates smaller volumes than IB, and lower dose homogeneity does not appear to affect toxicity. However, clinical experience suggests that other factors may also play an important role in cosmesis and toxicity with MSB. We reviewed our prospectively maintained data base of women who underwent accelerated partial breast irradiation (APBI) to assess this issue.

METHODS

Beginning in September 1995, 115 women were enrolled in a trial evaluating APBI as monotherapy after lumpectomy. The first 75 eligible patients received IB, and the most recent 28 eligible patients received MSB. All patients received 34 gray (Gy) in 10 twice-daily fractions through high-dose rate iridium-192 brachytherapy; 19% of patients in the IB group and 0% of patients in the MSB group received ACCT.

RESULTS

At 1 year after treatment, MSB caused significantly less Grade 2-4 subcutaneous fibrosis (as graded by a radiation oncologist according to the Radiation Therapy Oncology Group/Eastern Cooperative Oncology Group system) compared with IB (10.7% vs. 32%; P = 0.04). However, when only ACCT-naïve patients in the IB group were compared with patients in the MSB group, this finding became nonsignificant. Among the patients who received MSB, significantly smaller volumes were irradiated, and the DHI was lower.

CONCLUSIONS

Current studies suggest an improved toxicity profile with MSB compared with IB that is attributed to lower irradiated volumes with MSB. When only chemotherapy-naïve patients were compared, however, toxicity and cosmesis were found to be similar between MSB and IB, suggesting a more complex interplay between irradiated volumes, DHI, and chemotherapy. The relation of ACCT to toxicity in this scenario is intriguing and warrants further investigation.