Accelerated partial breast irradiation with interstitial implants: risk factors associated with increased local recurrence. Int J Radiat Oncol Biol Phys. 2011;80:1458-1463. [PMID: 20675064 DOI: 10.1016/j.ijrobp.2010.04.032]

Three-Fraction Accelerated Partial Breast Irradiation (APBI) Delivered With Interstitial Brachytherapy Is Safe: First Results From the Tri-fraction Radiation Therapy Used to Minimize Patient Hospital Trips (TRIUMPH-T) Trial

PURPOSE

Shorter courses of breast radiotherapy are offered as an alternative to 4 weeks of whole-breast irradiation after lumpectomy, including brachytherapy. A prospective phase 2multi-institution clinical trial to study 3-fraction accelerated partial breast irradiation delivered by brachytherapy was conducted.

METHODS AND MATERIALS

The trial treated selected breast cancers after breast-conserving surgery with brachytherapy applicators that delivered 22.5 Gy in 3 fractions of 7.5 Gy. The planning treatment volume was 1 to 2 cm beyond the surgical cavity. Eligible women were age ≥45 years with unicentric invasive or in situ tumors ≤3 cm excised with negative margins and with positive estrogen or progesterone receptors and no metastases to axillary nodes. Strict dosimetric parameters were required to be met and follow up information was collected from the participating sites.

RESULTS

Two hundred patients were prospectively enrolled; however, a total of 185 patients who were enrolled were followed for a median of 3.63 years. Three-fraction brachytherapy was associated with low chronic toxicity. There was excellent or good cosmesis in 94% of patients. There were no grade 4 toxicities. Grade 3 fibrosis at the treatment site was present in 1.7% and 32% percent had grades 1 or 2 fibrosis at the treatment site. There was 1 rib fracture. Other late toxicities included 7.4% grade 1 hyperpigmentation, 2% grade 1 telangiectasias, 1.7% symptomatic seromas, 1.7% abscessed cavities, and 1.1% symptomatic fat necrosis. There were 2 (1.1%) ipsilateral local recurrences, 2 (1.1%) nodal recurrences and no distant recurrences. Other incidents included one contralateral breast cancer and 2 second malignancies (lung).

CONCLUSIONS

Ultra-short breast brachytherapy is feasible and has excellent toxicity and could be an alternative to standard 5-day, 10 fraction accelerated partial breast irradiation in eligible patients. Patients from this prospective trial will continue to be followed to evaluate long-term outcomes.

Increased Risk for Ipsilateral Breast Tumor Recurrence in Invasive Lobular Carcinoma after Accelerated Partial Breast Irradiation Brachytherapy

BACKGROUND

The suitability criteria for accelerated partial breast irradiation (APBI) from the American Brachytherapy Society (ABS), American Society for Radiation Oncology (ASTRO), and The Groupe Européende Curiethérapie European SocieTy for Radiotherapy & Oncology (GEC-ESTRO) have significant differences.

MATERIALS AND METHODS

This is a single institution retrospective review of 946 consecutive patients with invasive breast cancer who underwent lumpectomy and APBI intracavitary brachytherapy from 2003 to 2018. Overall survival (OS), breast cancer-specific survival (BCSS), relapse-free survival (RFS), and ipsilateral breast tumor recurrence (IBTR) were estimated with Kaplan-Meier method.

RESULTS

Median follow-up time was 60.2 months. Median age was 68 years (46-94 years). The majority of patients had estrogen receptor (ER)-positive disease (94%). There were 821 (87%) cases of invasive ductal carcinoma and 68 cases (7%) of invasive lobular carcinoma (ILC). The 5-year OS, BCSS, RFS, and IBTR were 93%, 99%, 90%, and 1.5%, respectively. Upon univariate analysis, ILC (hazard ratio [HR], 4.6; p = .008) and lack of nodal evaluation (HR, 6.9; p = .01) were risk factors for IBTR. The 10-year IBTR was 2.5% for IDC and 14% for ILC. While the ABS and ASTRO criteria could not predict IBTR, the GEC-ESTRO intermediate risk group was associated with inferior IBTR (p = .04) when compared to both low risk and high risk groups. None of the suitability criteria was able to predict RFS.

CONCLUSION

These results show that APBI is an effective treatment for patients with invasive breast cancer. Expansion of the current eligibility criteria should be considered, although prospective validation is needed. Caution is required when considering APBI for patients with ILC.

IMPLICATIONS FOR PRACTICE

In a large retrospective review of 946 patients with early breast cancer treated with partial mastectomy and accelerated partial breast irradiation (APBI) intracavitary brachytherapy, this study demonstrates durable local control. Patients deemed unsuitable or high risk by the American Brachytherapy Society, American Society for Radiation Oncology, and European Society for Radiotherapy and Oncology guidelines were not at increased risk for ipsilateral breast tumor recurrence (IBTR), suggesting that expansion of the current criteria should be considered. Importantly, however, these results demonstrate that caution should be taken when considering APBI for patients with invasive lobular carcinoma, as these patients had relatively high risk for IBTR (10-year IBTR, 14%).

Tumour-Infiltrating Inflammatory Cells in Early Breast Cancer: An Underrated Prognostic and Predictive Factor?

The role of tumour-infiltrating inflammatory cells (TIICs) in the disease progression of hormone-receptor-positive breast cancer (HR+ BC) is largely unclear since it is generally regarded as the least immunogenic BC subtype. This study investigated the prognostic significance of CD1a+ dendritic cells, CD20+ B cells, CD45RO+ memory T cells and CD4+ T-helper cells in HR+ BC. One hundred and forty-six patients were treated for early stage, distant-metastases-free HR+ BC in an accelerated partial breast irradiation (APBI) phase II trial. Immunohistochemistry was used to double-stain two adjoining sets of tissue microarrays from pre-RT (radiotherapy) tumour resection samples for CD1a/CD20 and CD45RO/CD4. Cell densities of CD1a+, CD20+, CD45RO+ and CD4+ TIICs in the stromal and intraepithelial compartment were registered semiautomatically. High densities of CD20+ and CD4+ TIICs were strongly associated with reduced disease-free survival (DFS), while high stromal CD45RO+ TIIC densities were indicators of subsequent successful treatment. An immunoscore based on CD20+ and CD45RO+ TIIC densities identified three different risk groups (p < 0.001). Thus, contrary to current assumptions, intratumoural immune cell composition might be an important prognostic indicator and a possible contributing factor in the outcome of HR+ BC and should be the subject of further research. Specifically, B-cell infiltration entailed an increased relapse rate and could play an important role in disease progression.

Long-Term Results of Partial Breast Irradiation After Breast-Conserving Surgery for Early Stage Breast Cancer: A Prospective Phase II Trial in China

Background

Partial breast radiotherapy (PBI) has emerged as an option after breast-conserving surgery for early stage breast cancer patients.

Methods

A total of 55 patients with early stage breast cancer between 2009 and 2013 were enrolled in this single-institutional phase II prospective clinical trial. All patients received adjuvant PBI-IMRT after lumpectomy, with the prescription of 48 Gy in 12 fractions at 4 Gy per fraction, 5 days a week. The primary endpoint was ipsilateral breast tumor recurrence (IBTR), the other endpoints were a regional nodal failure (RNF), distant metastasis (DM) rate, disease-free survival (DFS), and overall survival (OS). These endpoints were used to evaluate clinical outcomes. The cosmetic effects and the late toxicity were assessed according to Harvard standard scale and CTCAE 3.0, respectively.

Results

In our cohorts, the median age was 45.60 years old (range 31-65 years) and 29.09% of these patients were post-menopause (n = 16). Most patients were T1 stage (65.45%) or N0 stage (70.91%). 80% of patients were ER-positive, 67.27% PR positive, and 61.82% HER2 negative. At the median follow-up of 9.25 years, RNF was 0% and IBTR occurred in only one patient (1.82%) to the chest wall. Except for one patient (1.82%) had DM to lung and pleura and died from disease progression, the remaining patients were alive at the end of the 10-year follow-up. The 10-year DFS and OS were 94.55 and 98.18%. One patient (1.82%) was diagnosed with endometrial cancer after PBI. Except for 9 patients who declined the cosmetic assessment, the rest of the 46 patients (83.64%) were all rated as good and well-satisfied with the appearance of the irradiated breast. No breast retraction and fibrosis were observed in any of the patients. Additionally, only 4 patients experienced grade 1 late toxicity (7.28%). None had grade 3 or higher late toxicity.

Conclusion

This is the first study to report the 10-year results of PBI after breast-conserving surgery in Chinese patients. Our study suggested that PBI had durable local control and maintained good cosmetic outcomes with minimal late toxicity at long term follow up for the early stage breast cancer patients.

Accelerated partial breast irradiation by brachytherapy: present evidence and future developments

Accelerated partial breast irradiation (APBI) delivers a short course of adjuvant RT after breast conserving surgery to only a limited part of the breast where the tumor was located. This procedure requires expertise, good communication, and close collaboration between specialized surgeons and attending radiation oncologists with adequate intraoperative tumor bed clip marking. However, APBI offers several intrinsic benefits when compared with whole breast irradiation (WBIR) including reduced treatment time (1 versus 4-6 weeks) and better sparing of surrounding healthy tissues. The present publication reviews the APBI level 1-evidence provided with various radiation techniques supplemented by long-term experience obtained from large multi-institutional phase II studies. Additionally, it offers an outlook on recent research with ultra-short or single-fraction APBI courses and new brachytherapy sources. Mature data from three randomized controlled trials (RCTs) clearly prove the noninferiority of APBI with 'only two techniques-1/MIBT (multicatheter interstitial brachytherapy) (two trials) and 2/intensity modulated radiotherapy (one trial)'-in terms of equivalent local control/overall survival to the previous standard 'conventionally fractionated WBIR'. However, MIBT-APBI techniques were superior in both toxicity and patient-reported outcomes (PROs) versus WBIR at long-term follow-up. Currently, in RCT-setting, alternative APBI techniques such as intraoperative electrons, 50-kV x-rays and three-dimensional conformal external beam radiotherapy (3D-CRT) failed to demonstrate noninferiority to conventionally fractionated WBIR. However, 3D-CRT-APBI compared noninferior to hypo-fractionated WBIR in preventing ipsilateral breast tumor recurrence (randomized RAPID-trial) but was associated with a higher rate of late radiation toxicity. Ultimately, MIBT remains the only APBI modality with noninferior survival/superior toxicity/PROs at 10-years and therefore should be prioritized over alternative methods in patients with breast cancer considered at low-risk for local recurrence according to recent international guidelines.

Three-Fraction Accelerated Partial Breast Irradiation (APBI) Delivered With Brachytherapy Applicators Is Feasible and Safe: First Results From the TRIUMPH-T Trial

PURPOSE

Shorter courses of accelerated partial-breast irradiation delivered as single-fraction intraoperative therapy are now offered as an alternative to 4 to 6 weeks of whole-breast irradiation after lumpectomy. However, this approach has potential shortcomings in patient selection and target volume definition and in dosimetric, radiobiological, and logistical issues. We designed a prospective, phase 2, multi-institution clinical trial to study 2- or 3-day accelerated partial breast irradiation delivered with brachytherapy applicators.

METHODS AND MATERIALS

This trial treats select breast cancers after breast-conserving surgery with brachytherapy applicators that deliver 22.5 Gy in 3 fractions of 7.5 Gy. The planning treatment volume was 1 to 1.5 cm beyond the surgical cavity. Eligible women were aged ≥45 years with unicentric invasive or in situ tumors ≤3.0 cm with positive estrogen or progesterone receptors and no metastasis to axillary nodes that have been excised with negative margins. Strict dosimetric parameters were required to be met before acceptance into the trial.

RESULTS

A group of 200 patients was prospectively enrolled and followed for a minimum of 6 months. Two- or 3-day brachytherapy was associated with low acute or subacute toxicity, 97.25% excellent or good cosmetic outcomes, and excellent local control in select breast cancers.

CONCLUSIONS

Ultrashort breast brachytherapy is dosimetrically feasible and can be delivered with excellent short-term tolerance and low toxicity.

Partial breast irradiation with interstitial multi-catheter high-dose-rate brachytherapy. Long-term results of a phase II prospective study

PURPOSE

We report the long-term results of phase II prospective study with accelerated partial breast irradiation (APBI) using interstitial multi-catheter high-dose-rate brachytherapy.

METHODS

240 patients received APBI (4Gy, twice daily; total dose 32Gy).

RESULTS

Median follow-up was 96months. Recurrences in the treated breast developed in 8 patients (3.3%) at a median of 73months after APBI. The 5- and 10-year cumulative incidences were respectively, 1.8% (95%CI: 0.6-4.3) and 6.6% (95%CI: 2.7-12.9). Regional recurrences developed in 5 patients (2%) at a median of 28months and distant metastases in 8 (3.3%) at a median of 32.5months. Breast cancer specific mortality occurred in 6 patients (2.5%) at a median of 60months. Acute toxicity developed in 71 (29.6%) patients (G1 in 60 and G2 in 11). Almost all were skin toxicity and hematomas. Late toxicity was observed in 90 patients (37.5%), G1 in 97 cases and G2 in 11. Some patients presented with more than one type of toxicity. Teleangectasia and fibrosis were the most common (48 and 44 cases respectively), followed by fat necrosis (in 18 patients) Tamoxifen emerged as the only risk factor for breast fibrosis (p=0.007). Cosmetic results were judged by the physicians as excellent in 174 (83.7%) patients, good in 25 (12%) fair in 8 (3.8%) and poor in 1 (0.5%); 174 patients (83.7%) judged outcomes as excellent, 26 (12.4%) as good, 7 (3.4%) as fair and 1 (0.5%) as poor. Physician/patient agreement was good (weighted k-value 0.72).

CONCLUSIONS

APBI with interstitial multi-catheter brachytherapy was associated with good outcomes, low relapse and toxicity rates. Few events during this long-term follow-up preclude identifying specific features of patients at risk of relapse and illustrate the need for a large data-base.

Accelerated partial breast irradiation: Past, present, and future

Accelerated partial breast irradiation (APBI) focuses higher doses of radiation during a shorter interval to the lumpectomy cavity, in the setting of breast conserving therapy for early stage breast cancer. The utilization of APBI has increased in the past decade because of the shorter treatment schedule and a growing body of outcome data showing positive cosmetic outcomes and high local control rates in selected patients undergoing breast conserving therapy. Technological advances in various APBI modalities, including intracavitary and interstitial brachytherapy, intraoperative radiation therapy, and external beam radiation therapy, have made APBI more accessible in the community. Results of early APBI trials served as the basis for the current consensus guidelines, and multiple prospective randomized clinical trials are currently ongoing. The pending long term results of these trials will help us identify optimal candidates that can benefit from ABPI. Here we provide an overview of the clinical and cosmetic outcomes of various APBI techniques and review the current guidelines for selecting suitable breast cancer patients. We also discuss the impact of APBI on the economics of cancer care and patient reported quality of life.

A review of the clinical experience in pulsed dose rate brachytherapy

Pulsed dose rate (PDR) brachytherapy is a treatment modality that combines physical advantages of high dose rate (HDR) brachytherapy with the radiobiological advantages of low dose rate brachytherapy. The aim of this review was to describe the effective clinical use of PDR brachytherapy worldwide in different tumour locations. We found 66 articles reporting on clinical PDR brachytherapy including the treatment procedure and outcome. Moreover, PDR brachytherapy has been applied in almost all tumour sites for which brachytherapy is indicated and with good local control and low toxicity. The main advantage of PDR is, because of the small pulse sizes used, the ability to spare normal tissue. In certain cases, HDR resembles PDR brachytherapy by the use of multifractionated low-fraction dose.

Accelerated partial breast irradiation with brachytherapy: patient selection and technique considerations

Accelerated partial breast irradiation (APBI) through breast brachytherapy is a relatively recent development in breast radiotherapy that has gained international favor because of its reduction in treatment duration and normal tissue irradiation while maintaining favorable cancer-specific and cosmetic outcomes. Despite the fact that several large national trials have not reported final results yet, many providers are currently offering APBI to select patients and APBI is listed as a treatment option for selecting patients in the National Comprehensive Cancer Network guidelines. Multiple consensus guidelines exist in selecting patients for APBI, some with conflicting recommendations. In this review, the existing patient selection guidelines are reported, compared, and critiqued, grouping them in helpful subcategories. Unique patient and technical selection factors for APBI with brachytherapy are explored.

Accelerated Partial Breast Irradiation in Clinical Practice

Accelerated partial breast irradiation (APBI) has been under clinical investigation for more than 15 years. There are several technical approaches that are clinically established, e.g. brachytherapy, intraoperative radiotherapy (IORT), or external-beam radiotherapy. The understanding of the underlying biology, optimal technical procedures, patient selection criteria, and imaging changes during follow-up has increased enormously. After completion of several phase III trials using brachytherapy or IORT, APBI is currently increasingly used either in phase IV studies, registries, or in selected patients outside of clinical studies. Consensus statements about suitable patients are available from several international and national societies like ASTRO, ESTRO, and DEGRO. One may expect that 15-25% of patients undergoing breast-conserving surgery may qualify for APBI, i.e. patients with small invasive ductal breast cancer without clinical lymph node involvement.

Comparison of planning techniques when air/fluid is present using the strut-adjusted volume implant (SAVI) for HDR-based accelerated partial breast irradiation

The presence of air/fluid surrounding implantable devices used for partial breast irradiation may significantly impact dose coverage to at-risk tissue. Of the 67 total patients retrospectively evaluated for this study, 32 (48%) had greater than 1 cc volume of air/fluid extending outside of the strut-adjusted volume implant (SAVI) device surface and were selected for comparison of planning approaches. The planning approaches utilized two different definitions of PTV_EVAL. One definition of a PTV_EVAL (PTV_EVALSAVI) was based on expanding 1 cm beyond the SAVI device only while accounting for the air/fluid using the NSABP Protocol B-39/RTOG Protocol 0413. The second PTV_EVAL definition (PTV_EVALCAV) was based on expanding 1 cm beyond the cavity (SAVI device plus air/fluid volume). The results indicate use of the B-39 formalism to account for air/fluid displacing the PTV_EVAL may overestimate the dose coverage to the at-risk tissue, especially for large contiguous volumes of air/fluid. Using the SAVI device to optimize dose covering the PTV_EVALCAV volume surrounding the cavity improves dosimetric coverage to at-risk tissue by 11.3% and 8.7% for V100 and V90, respectively, while the average V150 and V200 indices for PTV_EVALCAV increased by 9.1 cc and 5.0cc, respectively, and the average maximum rib and skin doses increased by 11.1% and 6.1%, respectively. The maximum skin dose, rib dose, V150, and V200 all met the planning objectives despite any increase in these parameters.

Outcome of a phase II prospective study on partial breast irradiation with interstitial multi-catheter high-dose-rate brachytherapy

BACKGROUND AND PURPOSE

Partial breast irradiation (PBI) is an alternative to whole-breast irradiation after breast-conserving surgery in selected patients. Until the results of randomized phase III studies are available, phase II studies inform about PBI. We report the 5 year results of a phase II prospective study with PBI using interstitial multi-catheter high-dose-rate brachytherapy (ClinicalTrials.gov Identifier: NCT00499057).

METHODS

Hundred patients received PBI (4 Gy, twice a day for 4 days, until 32 Gy). Inclusion criteria were: age ≥ 40years, infiltrating carcinoma without lobular histology, ductal in situ carcinoma, tumor size ≤ 2.5 cm, negative surgical margins and axillary lymph nodes.

RESULTS

At a median follow-up of 60 months late toxicity occurred in 25 patients; the 5-year probability of freedom from late toxicity was 72.6% (95% CI: 63.7-81.7). Tamoxifen was the only significant risk factor for late toxicity. Cosmetic results, judged by physicians and patients, were good/excellent in 98 patients. Three local relapses (1 true, 2 elsewhere) and 1 regional relapse occurred. The 5-year probability of local or regional relapse-free survival was 97.7% (95% CI: 91.1-99.4) and 99.0% (95% CI: 92.9-99.8), respectively.

CONCLUSION

PBI with interstitial multi-catheter brachytherapy is associated with low relapse and late toxicity rates.

Accelerated partial breast irradiation: the need for well-defined patient selection criteria, improved volume definitions, close follow-up and discussion of salvage treatment

Breast-conserving therapy, including whole breast irradiation, has become a well-established alternative to mastectomy in early-stage breast cancer patients, with similar survival rates and better cosmetic outcome. However, many women are still treated with mastectomy, due to logistical issues related to the long course of radiotherapy (RT). To reduce mastectomy rates and/or omission of RT after breast-conserving surgery, shorter, hypofractionated RT treatments have been introduced. More recently, the necessity of routinely treating the entire breast in all patients has been questioned, leading to the development of partial breast radiotherapy. With accelerated partial breast irradiation (APBI) these two approaches have been combined: the tumor bed with a 1-2 cm margin is irradiated either intra-operatively (single fraction) or postoperatively over 5-15 days. Different techniques have been developed, including interstitial brachytherapy, intra-cavity brachytherapy, intra-operative radiotherapy and external beam radiotherapy. These techniques are being evaluated in several ongoing phase III studies. Since its introduction, APBI has been the subject of continuous debate. ASTRO and GEC-ESTRO have published guidelines for patient selection for APBI, and strongly recommend that APBI be carried out within ongoing clinical trials. Recently, the patient selection criteria for APBI have also been up for debate, following the publication of results from different groups that do/do not confirm a difference in recurrence risk among the ASTRO defined risk groups. This paper reviews the different APBI techniques, current recommendations for patient selection, available clinical data and ongoing clinical trials. A case report is included to illustrate the need for careful follow-up of patients treated with APBI.

Accelerated partial breast irradiation using once-daily fractionation: analysis of 312 cases with four years median follow-up

BACKGROUND

There are limited data on accelerated partial breast irradiation (APBI) using external beam techniques. Moreover, there are recent reports of increased fibrosis and unacceptable cosmesis with APBI using external beam with BID fractionation. We adopted a once daily regimen of APBI with fractionation similar to that shown to be effective in a Canadian randomized trial of whole breast irradiation. It is unclear whether patients with DCIS or invasive lobular carcinoma (ILC) are suitable for APBI.

METHODS

The retrospective cohort included 310 patients with 312 tumors of T1-T2N0-N1micM0 invasive ductal carcinoma (IDC), ILC, or Tis (DCIS) treated with APBI via external beam. Most patients were treated using IMRT with 16 daily fractions of 270 cGy to a dose of 4320 cGy. The target volume included the lumpectomy cavity plus 1.0 cm to account for microscopic disease and an additional 0.5 to 1.0 cm for setup uncertainty and breathing motion. Ipsilateral breast failure (IBF) was pathologically confirmed as a local failure (LF) or an elsewhere failure (EF).

RESULTS

Median follow-up was 49 months. Among the 312 cases, 213 were IDC, 31 ILC, and 68 DCIS. Median tumor size was 1.0 cm. There were 9 IBFs (2.9%) including 5 LFs and 4 EFs. The IBF rates among patients with IDC, ILC, and DCIS were 2.4%, 3.2%, and 4.4%, respectively, with no significant difference between histologies. When patients were analyzed by the ASTRO APBI consensus statement risk groups, 32% of treated cases were considered suitable, 50% cautionary, and 18% unsuitable. The IBF rates among suitable, cautionary, and unsuitable patients were 4.0%, 2.6%, and 1.8%, respectively, with no significant difference between risk groups. Acute skin reactions were rare and long-term cosmetic outcome was very good to excellent.

CONCLUSIONS

External beam APBI with once daily fractionation has a low rate of IBF consistent with other published APBI studies. The ASTRO risk stratification did not differentiate a subset of patients with a higher rate of IBF. APBI may be an appropriate treatment for women with DCIS and ILC.

Surgical perspectives from a prospective, nonrandomized, multicenter study of breast conserving surgery and adjuvant electronic brachytherapy for the treatment of breast cancer

BACKGROUND

Accelerated partial breast irradiation (APBI) may be used to deliver radiation to the tumor bed post-lumpectomy in eligible patients with breast cancer. Patient and tumor characteristics as well as the lumpectomy technique can influence patient eligibility for APBI. This report describes a lumpectomy procedure and examines patient, tumor, and surgical characteristics from a prospective, multicenter study of electronic brachytherapy.

METHODS

The study enrolled 65 patients of age 45-84 years with ductal carcinoma or ductal carcinoma in situ, and 44 patients, who met the inclusion and exclusion criteria, were treated with APBI using the Axxent® electronic brachytherapy system following lumpectomy. The prescription dose was 34 Gy in 10 fractions over 5 days.

RESULTS

The lumpectomy technique as described herein varied by site and patient characteristics. The balloon applicator was implanted by the surgeon (91%) or a radiation oncologist (9%) during or up to 61 days post-lumpectomy (mean 22 days). A lateral approach was most commonly used (59%) for insertion of the applicator followed by an incision site approach in 27% of cases, a medial approach in 5%, and an inferior approach in 7%. A trocar was used during applicator insertion in 27% of cases. Local anesthetic, sedation, both or neither were administered in 45%, 2%, 41% and 11% of cases, respectively, during applicator placement. The prescription dose was delivered in 42 of 44 treated patients.

CONCLUSIONS

Early stage breast cancer can be treated with breast conserving surgery and APBI using electronic brachytherapy. Treatment was well tolerated, and these early outcomes were similar to the early outcomes with iridium-based balloon brachytherapy.