The American Brachytherapy Society consensus statement for accelerated partial breast irradiation

Invasive lobular breast cancer: Focus on prevention, genetics, diagnosis, and treatment

Invasive lobular cancer (ILC) is the most common of the breast cancer special types, accounting for up to 15% of all breast malignancies. The distinctive biological features of ILC include the loss of the cell adhesion molecule E-cadherin, which drives the tumor's peculiar discohesive growth pattern, with cells arranged in single file and dispersed throughout the stroma. Typically, such tumors originate in the lobules, are more commonly bilateral compared to invasive ductal cancer (IDC) and require a more accurate diagnostic examination through imaging. They are luminal in molecular subtype, and exhibit estrogen and progesterone receptor positivity and HER2 negativity, thus presenting a more unpredictable response to neoadjuvant therapies. There has been a significant increase in research focused on this distinctive breast cancer subtype, including studies on its pathology, its clinical and surgical management, and the high-resolution definition of its genomic profile, as well as the development of new therapeutic perspectives. This review will summarize the heterogeneous pattern of this unique disease, focusing on challenges in its comprehensive clinical management and on future insights and research objectives.

Cost-effectiveness of intraoperative radiation therapy versus intensity-modulated radiation therapy for the treatment of early breast cancer: a disinvestment analysis

BACKGROUND

Adjuvant radiotherapy represents a key component in curative-intent treatment for early-stage breast cancer patients. In recent years, two accelerated partial breast irradiation (APBI) techniques are preferred for this population in our organization: electron-based Intraoperative radiation therapy (IORT) and Linac-based External Beam Radiotherapy, particularly Intensity-modulated radiation therapy (IMRT). Recently published long-term follow-up data evaluating these technologies have motivated a health technology reassessment of IORT compared to IMRT.

METHODS

We developed a Markov model to simulate health-state transitions from a cohort of women with early-stage breast cancer, after lumpectomy and adjuvant APBI using either IORT or IMRT techniques. The cost-effectiveness from a private health provider perspective was assessed from a disinvestment point of view, using life-years (LYs) and recurrence-free life-years (RFLYs) as measure of benefits, along with their respective quality adjustments. Expected costs and benefits, and the incremental cost-effectiveness ratio (ICER) were reported. Finally, a sensitivity and scenario analyses were performed to evaluate the cost-effectiveness using lower IORT local recurrence and metastasis rates in IORT patients, and if equipment maintenance costs are removed.

RESULTS

IORT technology was dominated by IMRT in all cases (i.e., fewer benefits with greater costs). Despite small differences were found regarding benefits, especially for LYs, costs were considerably higher for IORT. For sensitivity analyses with lower recurrence and metastasis rates for IORT, and scenario analyses without equipment maintenance costs, IORT was still dominated by IMRT.

CONCLUSIONS

For this cohort of patients, IMRT was, at least, non-inferior to IORT in terms of expected benefits, with considerably lower costs. As a result, IORT disinvestment should be considered, favoring the use of IMRT in these patients.

Novel Form of Breast Intraoperative Radiation Therapy with CT-Guided High-Dose-Rate Brachytherapy: Interim Results of a Prospective Phase-II Clinical Trial

BACKGROUND

Precision breast intraoperative radiation therapy (PB-IORT) is a novel method of IORT that uses customized CT-based treatment plans and high-dose-rate (HDR) brachytherapy. We conducted a phase-II multi-institution trial to evaluate the efficacy of PB-IORT.

STUDY DESIGN

Between 2015 and 2022, 3 centers enrolled women aged 45 years and older with invasive or in situ carcinoma measuring 3 cm or smaller and N0 status (n = 358). Breast-conserving surgery was performed, and a multilumen balloon catheter was placed in the lumpectomy bed. CT images were used to create customized HDR brachytherapy plans that delivered 12.5 Gy to the tumor bed. The primary outcome assessed was the 5-year rate of index quadrant tumor recurrence. An interim analysis was conducted after one-third of eligible participants completed 5 years of follow-up. This trial is registered with clinicaltrials.gov (NCT02400658).

RESULTS

The cohort comprised 153 participants with a median age of 64 years and median follow-up time of 5.9 years. The estimated 5-year index quadrant tumor recurrence rate and overall survival were 5.08% (95% CI 2.23 to 9.68) and 95.1%, respectively. Locoregional (ipsilateral breast and axilla) and distant recurrence rates were each 1.96%. Seven deaths occurred during the first 5 years of follow-up, with only 1 attributable to breast cancer. Overall, 68.6% of patients experienced any adverse effects, and 4 cases of breast-related severe toxicities were observed.

CONCLUSIONS

This study presents the results of a planned interim analysis of a phase-II trial investigating PB-IORT and demonstrates the efficacy and safety of single-fraction, CT-based, HDR brachytherapy after breast-conserving surgery. These findings provide valuable insights into the use of PB-IORT as a treatment modality.

Experience with intraoperative radiation therapy in an urban cancer center

BACKGROUND/OBJECTIVE

Intra-operative radiation therapy (IORT) is a newer partial breast irradiation technique that has been well studied in 2 large randomized trials, the TARGIT-A and ELIOT trials. We initiated our IORT program in 2018 in the context of a registry trial, and aim to report our early results thus far.

METHODS

We instituted an IORT practice using Intrabeam® low energy 50kVp x-rays for selected breast cancer cases in 2018. Patients were enrolled on our institutional registry protocol which allowed for IORT in ER + patients with grade 1-2 DCIS ≤ 2.5 cm or invasive disease ≤ 3.5 cm in patients of at least 45 years of age.

RESULTS

Between January 2018 and December 2021, 181 patients with clinical stage 0-IIA ER + breast cancer were evaluated. One hundred sixty-seven patients ultimately received IORT to 172 sites. The majority of patients received IORT at the time of initial diagnosis and surgery (160/167; 95.8%). Re-excision post IORT occurred in 16/167 patients (9.6%) due to positive margins. Adjuvant RT to the whole breast +/- LN was ultimately given to 23/167 (13.8%) patients mainly due to positive sentinel LN found on final pathology (12/23; 52%); other reasons were close margins for DCIS (3/23; 13%), tumor size (3/23; 4.3%), and multifactorial (5/23; 17.4%). Five patients (3%) had post-operative complications of wound dehiscence. There were 3 local recurrences (1.6%) at a median follow-up of 27.9 months (range: 0.7- 54.8 months).

CONCLUSIONS

IORT has been proven to be a safe and patient-centered form of local adjuvant RT for our population, in whom compliance with a longer course of external beam radiation can be an issue. Long term efficacy remains to be evaluated through continued follow up. In the era of COVID-19 and beyond, IORT has been an increasingly attractive option, as it greatly minimizes toxicities and patient visits to the clinic.

TRIAL REGISTRATION

All patients were prospectively enrolled on an institutional review board-approved registry trial (IRB number: 2018-9409).

What Is Known about Breast Cancer in Young Women?

Breast cancer (BC) is the second leading cause of cancer-related death in women under the age of 40 years worldwide. In addition, the incidence of breast cancer in young women (BCYW) has been rising. Young women are not the focus of screening programs and BC in younger women tends to be diagnosed in more advanced stages. Such patients have worse clinical outcomes and treatment complications compared to older patients. BCYW has been associated with distinct tumour biology that confers a worse prognosis, including poor tumour differentiation, increased Ki-67 expression, and more hormone-receptor negative tumours compared to women >50 years of age. Pathogenic variants in cancer predisposition genes such as BRCA1/2 are more common in early-onset BC compared to late-onset BC. Despite all these differences, BCYW remains poorly understood with a gap in research regarding the risk factors, diagnosis, prognosis, and treatment. Age-specific clinical characteristics or outcomes data for young women are lacking, and most of the standard treatments used in this subpopulation currently are derived from older patients. More age-specific clinical data and treatment options are required. In this review, we discuss the epidemiology, clinicopathologic characteristics, outcomes, treatments, and special considerations of breast cancer in young women. We also underline future directions and highlight areas that require more attention in future studies.

Special Techniques of Adjuvant Breast Carcinoma Radiotherapy

Modern radiotherapy techniques are designed to permit reduced irradiation of healthy tissue, resulting in a diminished risk of adverse effects and shortened recovery times. Several randomized studies have demonstrated the benefits of increased dosage to the tumor bed area in combination with whole breast irradiation (WBI). Conventional WBI treatment following breast-conserving procedures, which required 5-7 weeks of daily treatments, has been reduced to 3-4 weeks when using hyperfractionated regimens. The dosage administration improves local control, albeit with poorer cosmesis. The method of accelerated partial breast irradiation (APBI) shortens the treatment period whilst reducing the irradiated volume. APBI can be delivered using intraoperative radiation, brachytherapy, or external beam radiotherapy. Currently available data support the use of external beam partial breast irradiation in selected patients. Modern radiotherapy techniques make it possible to achieve favorable cosmesis in most patients undergoing immediate breast reconstruction surgery, and studies confirm that current methods of external beam radiation allow an acceptable coverage of target volumes both in the reconstructed breast and in the regional lymphatic nodes.

H&N and Skin (HNS) GEC-ESTRO Working Group critical review of recommendations regarding prescription depth, bolus thickness and maximum dose in skin superficial brachytherapy with flaps and customized moulds

The aim of this publication is the assessment of the existing guidelines for non-melanoma skin cancer (NMSC) superficial brachytherapy (BT) and make a critical review based on the existing literature about the maximum dose prescription depth, bolus thickness and maximum skin surface dose (D_max) of the published clinical practice. A systematic review of NMSC superficial BT published articles was carried out by the GEC-ESTRO Head & Neck and Skin (HNS) Working Group (WG). 10 members and 2 external reviewers compared the published clinical procedures with the recommendations in the current guidelines and examined the grade of evidence. Our review verified that there is a large variation among centres with regards to clinical practice in superficial BT and identified studies where published parameters such as maximum dose prescription depth, bolus thickness and D_max exceed the constraints recommended in the guidelines, while showing excellent results in terms of local control, toxicity and cosmesis. This review confirmed that current recommendations on skin superficial BT do not include published experience on tumours treated with superficial BT that require dose prescription depth beyond the recommended 5mm under the skin surface and that the existing literature does not provide sufficient evidence to relate dosimetry of superficial BT to patient reported outcome measures. The GEC-ESTRO HNS WG considers acceptable to prescribe superficial BT dose at a depth above 5mm beyond the skin surface, and modify the bolus thickness to optimize the treatment plan and adjust the acceptable maximum dose on the skin surface, all pending clinical situation.

ACR-ABS-ASTRO Practice Parameter for the Performance of Low-Dose-Rate Brachytherapy

AIM/OBJECTIVES/BACKGROUND

The American College of Radiology (ACR), the American Brachytherapy Society (ABS), and the American Society for Radiation Oncology (ASTRO) have jointly developed the following practice parameter for the performance of low-dose-rate (LDR) brachytherapy. LDR brachytherapy is the application of radioactive sources in or on tumors in a clinical setting with therapeutic intent. The advantages of LDR brachytherapy include improving therapeutic ratios with lower doses to nontarget organs-at-risk and higher doses to a specific target.

METHODS

This practice parameter was developed according to the process described under the heading. The Process for Developing ACR Practice Parameters and Technical Standards on the ACR website (https://www.acr.org/Clinical-Resources/Practice-Parameters-and-Technical-Standards) by the Committee on Practice Parameters-Radiation Oncology of the Commission on Radiation Oncology, in collaboration with ABS and ASTRO.

RESULTS

This practice parameter was developed to serve as a tool in the appropriate application of this evolving technology in the care of cancer patients or other patients with conditions where radiation therapy is indicated. It addresses clinical implementation of LDR brachytherapy including personnel qualifications, quality assurance standards, indications, and suggested documentation. This includes a contemporary literature search.

CONCLUSIONS

This practice parameter is a tool to guide the use of LDR brachytherapy and does not assess relative clinical indication for LDR brachytherapy when compared with other forms of brachytherapy or external beam therapy, but to focus on the best practices required to deliver LDR brachytherapy safely and effectively, when clinically indicated. Comparative costs of versus other modalities therapy may also need to be considered.

TARGIT-R (Retrospective): 5-Year Follow-Up Evaluation of Intraoperative Radiation Therapy (IORT) for Breast Cancer Performed in North America

BACKGROUND

Intraoperative radiation therapy (IORT) has been investigated for patients with low-risk, early-stage breast cancer. The The North American experience was evaluated by TARGIT-R (retrospective) to provide outcomes for patients treated in "real-world" clinical practice with breast IORT. This analysis presents a 5-year follow-up assessment.

METHODS

TARGIT-R is a multi-institutional retrospective registry of patients who underwent lumpectomy and IORT between the years 2007 and 2013. The primary outcome of the evaluation was ipsilateral breast tumor recurrence (IBTR).

RESULTS

The evaluation included 667 patients with a median follow-up period of 5.1 years. Primary IORT (IORT at the time of lumpectomy) was performed for 72%, delayed IORT (after lumpectomy) for 3%, intended boost for 8%, and unintended boost (primary IORT followed by whole-breast radiation) for 17% of the patients. At 5 years, IBTR was 6.6% for all the patients, with 8% for the primary IORT cohort and 1.7% for the unintended-boost cohort. No recurrences were identified in the delayed IORT or intended-boost cohorts. Noncompliance with endocrine therapy (ET) was associated with higher IBTR risk (hazard ratio [HR], 3.67). Patients treated with primary IORT who were complaint with ET had a 5-year IBTR rate of 3.9%.

CONCLUSION

The local recurrence rates in this series differ slightly from recent results of randomized IORT trials and are notably higher than in previous published studies using whole-breast radiotherapy for similar patients with early-stage breast cancer. Understanding differences in this retrospective series and the prospective trials will be critical to optimizing patient selection and outcomes going forward.

A comparison of long-term clinical outcomes of accelerated partial breast irradiation using interstitial brachytherapy as per GEC-ESTRO, ASTRO, updated ASTRO, and ABS guidelines

PURPOSE

The purpose of this study is to evaluate long-term clinical outcomes of women treated with accelerated partial breast irradiation (APBI) using multicatheter interstitial brachytherapy (MIB-APBI) with risk groups defined by Groupe Européen de Curie-thérapie and the European Society for Radiotherapy & Oncology (GEC-ESTRO), American Society for Radiation Oncology (ASTRO), updated ASTRO, and American Brachytherapy Society (ABS) guidelines and to elucidate the most appropriate guideline that could differentiate outcomes among its risk groups.

METHODS AND MATERIALS

Two hundred forty women underwent MIB-APBI during July 2000 to March 2013. Comparisons of long-term clinical outcomes (local control [LC], disease-free survival [DFS], cause-specific survival [CSS], and overall survival [OAS]) stratified by the risk groups proposed by the aforementioned patient selection guidelines were carried out on a prospectively maintained database.

RESULTS

At a median follow-up of 114 months, 10-year LC, DFS, and OAS were 90%, 81%, and 83.5%, respectively, for the entire group. There was no statistically significant difference in the LC rates for risk groups by ESTRO, ASTRO, updated ASTRO and ABS guidelines. The 10-year DFS and OAS for GEC-ESTRO low-, intermediate-, and high-risk group was 75%, 88%, and 60% (p = 0.02) and 86%, 93%, and 62% (p = 0.001), respectively. Ten-year DFS and OAS in the ABS 2018-acceptable and ABS 2018-unacceptable group were 78% and 67% (p = 0.01) and 88% and 69% (p = 0.001), respectively. No significant difference in any of the outcomes was observed with risk groups suggested by ASTRO or updated ASTRO consensus guidelines.

CONCLUSIONS

None of the current patient selection guidelines for APBI could differentiate LC (main APBI endpoint) among its risk groups, whereas GEC-ESTRO and ABS guideline could differentiate DFS and OAS.

Development of an HDR-BT QA tool for source position verification

PURPOSE

This study aimed to develop a high-dose-rate brachytherapy (HDR-BT) quality assurance (QA) tool for verification of source positions, and to report on its effectiveness.

METHODS

We fabricated a cuboid phantom measuring 30 × 30×3 cm³ with spaces to embed Fletcher-Williamson tandem and ovoid applicators. Lead-based, cylindrically shaped radiopaque markers, which scatter radiation and blacken the Gafchromic^® RTQA2 films placed on the applicators, were inserted into the phantom to determine the applicator tip and reference source positions. A three-dimensional image-guided brachytherapy (3D-IGBT) plan was generated, and the source positions on the film and radiation treatment planning system (RTPS) were verified with the tool. Source position errors were evaluated as the distance in the applicator axis direction between the source position and the center position of two radiopaque marker pairs.

RESULTS

Source position errors on the film and RTPS were in good agreement with one another and were all within 0.5 mm for all applicators. Offset values of each applicator were in good agreement with the value determined in treatment planning (6 mm). The expanded measurement uncertainty of our QA tool was estimated to be 0.87 mm, with a coverage factor k of 2.

CONCLUSIONS

Our new HDR-BT QA tool developed for comprehensive source position verification will be useful for cross checking actual source positions and planned source positions on the RTPS.

Who are the optimal candidates for partial breast irradiation?

At the 2017 St. Gallen International Expert Consensus Conference on the Primary Therapy for Early Breast Cancer, the consensus panel recognized "partial breast irradiation as an option for women meeting the low-risk criteria put forward by the American Society for Radiation Oncology/European Society for Radiotherapy and Oncology (ASTRO/ESTRO) guideline," although acknowledging that there was less evidence for this approach. Partial breast irradiation is defined as irradiation localized to the surgical resection cavity only as opposed to the entire breast. Accelerated partial breast irradiation (APBI) involves intensive treatment in a short time period. The methods vary, and three available APBI options are brachytherapy, external beam and intra-operative irradiation. The long-term follow-up results from two large-scale, well-designed phase III randomized clinical trials have been released. However, further discussion of the optimal treatment candidates and delivery method is needed before the clinical application of APBI as a mainstream breast conservation treatment.

The ABS brachytherapy schools

The American Brachytherapy Society brachytherapy schools have been pivotal in teaching and evolving the art of brachytherapy over the past decades. Founded in 1995, the schools have consistently provided content for the major disease sites including gynecologic, prostate, and breast with ocular, vascular, head and neck, pediatric, intraluminal, systemic, and intraoperative approaches more selectively addressed. In addition, Physics schools, either coupled with clinical schools or as stand-alone venues, have provided an essential educational component for practicing physicists, a pivotal part of the brachytherapy team. Celebrating 25 years in existence, this historical overview of the American Brachytherapy Society brachytherapy schools is a tribute to the many teachers who have shared their expertise, to the many students who have been enthusiastic and interactive participants, and the staff who have made it all possible, with the reward of perpetuating the important and timely art of brachytherapy.

A reliable skin toxicity predictor in permanent breast seed implant brachytherapy

PURPOSE

To establish skin dose-outcome relationships using a reliable metric in permanent breast seed implant (PBSI).

METHODS

Sixty-seven consecutive patients who underwent PBSI at our institution were included. Skin doses were calculated using two skin dose indices: maximum point dose to the skin surface, D_max, and D_0.2cc for a 2-mm internal skin rind (a surrogate to the dose to 1 cm² area of skin) from CT-based postoperative treatment plans. Toxicity data were extracted from patients' charts and photographs. The associations between skin dose and skin toxicity were investigated using the analysis of variance, and the predictive performance of skin dose measures was evaluated using receiver operating characteristic curves.

RESULTS

For acute reactions, 49.3% of patients had Grade 1, 4.5% Grade 2, and 1.5% Grade 3 toxicity. For telangiectasia at 3 years, very minor and minimally apparent telangiectasia was observed in 25% of patients. Moderate but asymptomatic telangiectasia was observed in 9.1% of cases. Both metrics were significantly associated with the occurrence of acute toxicity and telangiectasia at 3 years (p < 0.01). The predictive values for D_max and D_0.2cc were 0.779 and 0.763, respectively, (p < 0.0001) for acute skin toxicity and 0.786 and 0.810 for telangiectasia (p < 0.0002). Extreme dose outliers (up to 878 Gy) and a high variability were observed for D_max but not for D_0.2cc, illustrating the superior reliability of D_0.2cc.

CONCLUSION

D_0.2cc, as an alternate skin dose measure to D_max, is a robust metric for measuring skin dose that is simple to calculate, yet is clinically relevant and not prone to inaccuracies inherent to point dose measurement.

The use of hyaluronic acid hydrogel as a tumour bed marker in breast-conserving therapy

PURPOSE

To evaluate usefulness of hyaluronic acid (HA) hydrogel as a tumour bed marker in breast conserving therapy (BCT). To analyze inter- (Inter-OV) and intraobserver (Intra-OV) variability of contouring boost target volume (CTV_boost) in external beam radiotherapy (EBRT).

MATERIALS AND METHODS

Thirty-two patients in the HA group and 30 patients in the control group with an early stage breast cancer were included in the study. During the surgery 1-3 ml of HA hydrogel was injected into breast to mark the tumour bed for every patient in the HA group. Moreover, surgical clips were placed underneath the lumpectomy cavity. Patients in the control group were marked only by metal markers. Three radiation oncologists delineated CTV_boost twice for every patient. Three parameters were calculated to quantify contouring variability: coefficient of variation for volumes (COV_V), center of mass displacement (CoMd) and conformity index (CI).

RESULTS

There were no significant differences between mean values of COV_V for HA and control group, neither for Intra-OV (0.14 vs 0.13) nor Inter-OV (0.19 vs 0.18) calculations. The mean CoMd were 6.1 mm and 9.1 mm for Inter-OV calculations and 3.9 mm and 6.4 mm for Intra-OV in the HA and the control group respectively. The mean CI for Intra-OV improved from 0.61 to 0.65 and from 0.47 to 0.56 for Inter-OV in the control and HA group respectively.

CONCLUSION

HA hydrogel used as a tumour bed marker improves tumour bed visibility and reduces inter- and intraobserver variability of EBRT boost target volume delineations.

COVID-19 impact on timing of brachytherapy treatment and strategies for risk mitigation

PURPOSE

The purpose of this study was to highlight the importance of timely brachytherapy treatment for patients with gynecologic, breast, and prostate malignancies, and provide a framework for brachytherapy clinical practice and management in response to the COVID-19 pandemic.

METHODS AND MATERIALS

We review amassing evidence to help guide the management and timing of brachytherapy for gynecologic, breast, and prostate cancers. Where concrete data could not be found, peer-reviewed expert opinion is provided.

RESULTS

There may be a significant negative impact on oncologic outcomes for patients with gynecologic malignancies who have a delay in the timely completion of therapy. Delay of prostate or breast cancer treatment may also impact oncologic outcomes. If a treatment delay is expected, endocrine therapy may be an appropriate temporizing measure before delivery of radiation therapy. The use of shorter brachytherapy fractionation schedules will help minimize patient exposure and conserve resources.

CONCLUSIONS

Brachytherapy remains a critical treatment for patients and may shorten treatment time and exposure for some. Reduced patient exposure and resource utilization is important during COVID-19. Every effort should be made to ensure timely brachytherapy delivery for patients with gynecologic malignancies, and endocrine therapy may help temporize treatment delays for breast and prostate cancer patients. Physicians should continue to follow developing institutional, state, and federal guidelines/recommendations as challenges in delivering care during COVID-19 will continue to evolve.

Accelerated partial breast irradiation with interstitial multicatheter brachytherapy after breast-conserving surgery for low-risk early breast cancer

Patients with low-risk invasive ductal carcinoma treated with breast-conserving surgery (BCS) were included in a multicatheter brachytherapy APBI protocol. The primary endpoint was ipsilateral breast recurrence. Between December 2008–December 2017, 186 low-risk breast cancer patients were treated with APBI using interstitial multicatheter brachytherapy and followed prospectively. At 5-years of follow-up, cumulative local recurrence (LR) and cause-specific survival was 1.1% (95% CI 0.3–1.9) and 98.3% (95% CI 97.3–99.3%) respectively. No grade 3 adverse effects were observed. Postoperative APBI using multicatheter brachytherapy after BCS in early breast cancer patients have excellent rates of local control and survival, without significant toxicity.

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Low risk early breast cancer patients have low rate of recurrences.

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APBI with interstitial multicatheter brachytherapy in low risk early breast cancer patients have excellent rates of local control and survival.

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Reducing time of treatment.

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Reducing adverse effects.

Margin assessment before intraoperative radiotherapy during breast conserving surgery-Does the addition of MarginProbe decrease the need for addition of fractionated whole breast radiation?

When performing Breast Conserving Surgery (BCS) with Intraoperative Radiation Therapy (IORT), positive resection margin necessitates not only re-lumpectomy-but also the addition of fractionated whole breast radiation. This retrospective study of 106 patients undergoing BCS and IORT aims to evaluate intraoperative margin assessment use in our center, and the contribution of the MarginProbe device (MP) to achieving negative surgical margins. Eleven out of 106 lumpectomy specimens had a total of 17 margins positive for tumor cells. Intraoperative gross pathology identified 6 (43%) involved margins, MarginProbe detected 8 (50%), and their combined use allowed for detection of 12 (70.5%) involved margins. In conclusion, the adjunctive use of intraoperative gross pathology and MarginProbe reduced the number of lumpectomies with positive resection margins by more than 50%, decreasing the need for re-lumpectomy and the addition of whole breast radiation.

First Experience in Korea of Stereotactic Partial Breast Irradiation for Low-Risk Early-Stage Breast Cancer

Purpose: Accelerated partial breast irradiation (A-PBI) in Korean women has been considered impracticable, owing to small breast volume and lack of high-precision radiotherapy experience. We present the first experience of stereotactic-PBI (S-PBI) with CyberKnife M6 to investigate feasibility of use and early toxicities in Korean women with early breast cancers.

Materials and Methods: A total of 104 breasts receiving S-PBI at our institution between September 2017 and October 2018 were reviewed. Patients were selected based on the American Society for Radiation Oncology (ASTRO), American Brachytherapy Society, American Society of Breast Surgeons, and Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology guidelines. A dose of 30 Gy in 5 fractions (NCT01162200) was used. Gold fiducials were routinely inserted near the tumor bed for tracking. Constraints regarding organs-at-risk followed the NSABP-B39/RTOG 0413 protocol.

Results: Median follow-up was for 13 months. Patients were categorized as “suitable” (71.2%) or “cautionary” (28.8%) according to 2017 the ASTRO guidelines. No tracking failure of inserted gold fiducials occurred. Median planning target volume (PTV) and PTV-to-whole breast volume ratio was 73.6 mL (interquartile range, 58.8–103.9 mL) and 17.0% (13.3–19.1%), respectively. Median PTV V_95%, PTV D_max, and ipsilateral breast V_50% were 97.8% (96.2–98.8%), 105.3% (104.2–106.4%), and 35.5% (28.3–39.8%), respectively. No immediate post-S-PBI toxicity ≥ grade 2 was reported, except grade 2 induration in three breasts. All patients remain disease-free to date.

Conclusion: The first use of S-PBI in Korean women was feasible and safe for selected early breast cancer. Based on these results, we have initiated a prospective study (NCT03568981) to test S-PBI in whole-breast irradiation for low-risk early breast cancer.

DEGRO practical guideline for partial-breast irradiation

Purpose

This consensus statement from the Breast Cancer Working Group of the German Society for Radiation Oncology (DEGRO) aims to define practical guidelines for accelerated partial-breast irradiation (APBI).

Methods

Recent recommendations for relevant aspects of APBI were summarized and a panel of experts reviewed all the relevant literature. Panel members of the DEGRO experts participated in a series of conferences, supplemented their clinical experience, performed a literature review, and formulated recommendations for implementing APBI in clinical routine, focusing on patient selection, target definition, and treatment technique.

Results

Appropriate patient selection, target definition for different APBI techniques, and basic rules for appropriate APBI techniques for clinical routine outside of clinical trials are described. Detailed recommendations for APBI in daily practice, including dose constraints, are given.

Conclusion

Guidelines are mandatory to assure optimal results of APBI using different techniques.

Radiochromic film in vivo dosimetry predicts early the risk of acute skin toxicity for brachytherapy partial breast irradiation

Brachytherapy accelerated partial breast irradiation (APBI) is well tolerated, but reported acute toxicities including moist desquamation rates range from 7% to 39%. Moist desquamation is correlated to long-term skin toxicity and high skin dose is the main risk factor. This study uses radiochromic films for in vivo skin dosimetry of low dose rate (LDR) APBI brachytherapy and prediction of skin toxicity. Patients participating in a clinical trial assessing skin toxicity of LDR seed brachytherapy were included in this study. Following the seed implantation procedure, patients were asked to wear a customized oval shaped radiochromic film on the skin projection of the planned target volume (PTV) for 24 h. Exposed films were collected, and maximum point doses were measured. In addition, maximum doses to a small skin volume (D_0.2cc) were calculated on the pre- and post-implant CT-scan. Acute skin toxicities (redness, pigmentation, induration and dermatitis) were scored by the treating physician for 2 months during follow-up visits. Skin dose measurements and acute toxicity were available for 18 consecutive patients. The post-implant calculated maximum skin doses (D_0.2cc), 60.8 Gy (SD ± 41.0), were on average 30% higher than those measured in vivo (D_max-film), 46.6 Gy (SD ± 19.3), but those values were highly significantly correlated (Spearman's rho 0.827, p < 0.001). Also, dermatitis and induration were significantly correlated with higher in vivo measured and post-implant calculated skin dose. Pre-implant dosimetry was not correlated with measured or post-implant skin dose or side effects. Radiochromic films can reliably diagnose excess dose to the skin during the first 24 h and predict skin toxicity, which enables preventative measures. Trial registration: Nederlands Trial Register (www.trialregister.nl), NTR6549, the trial was registered prospectively on 27 June 2017. ABR number: NL56210.078.16.

Dosimetric Limitations in Treating Breast Cancer with Accelerated Partial Breast Irradiation Using Strut Adjusted Volume Implant (SAVI)

We present one case of accelerated partial breast irradiation (APBI) using strut adjusted volume implant (SAVI) where there were limitations in delivering the dose as per the standard guidelines. The device was placed close to both the chest wall and the skin with little tissue surrounding the tip. Two plans were made in an attempt to achieve the standard therapeutic doses without over-treating the chest wall or the skin. Similar cases reported in the literature were reviewed. The dosimetry of the two plans was compared to the cases discussed in the literature.

Could a Personalized Strategy Using Accelerated Partial Breast Irradiation be an Advantage for Elderly Patients? A Systematic Review of the Literature and Multidisciplinary Opinion

Introduction. Elderly patients are underrepresented from a majority of clinical trials and the choice of the best treatment becomes a challenge. The optimal treatment should be personalized and based on a multidisciplinary approach that includes radiation oncologists, surgeons, geriatricians, medical oncologists, social workers, and support services. The global evaluation of the patients and the creation of nomograms may facilitate the definition of long-term treatment benefits minimizing the use of unnecessary therapy. Material and Method. A systematic research using PubMed, Scopus, and Cochrane library was performed to identify full articles analyzing the efficacy of APBI in elderly patients with breast cancer. ClinicalTrials.gov was searched for ongoing or recently completed trials, and PROSPERO was searched for ongoing or recently completed systematic reviews.

Multicentric breast cancer with heterogeneous histopathology: a multidisciplinary review

Multiple synchronous (multifocal or multicentric) ipsilateral breast cancers with heterogeneous histopathology are a rare clinical occurrence, however, their incidence is increasing due to the use of MRI for breast cancer screening and staging. Some studies have demonstrated poorer clinical outcomes for this pattern of breast cancer, but there is no evidence to guide clinical practice. In this multidisciplinary review, we reflect on pathology and molecular characteristics, imaging findings, surgical management including conservation and reconstructive options and approach to the axilla, and the role of chemotherapy and radiotherapy. Multidisciplinary discussions appear decisive in planning an appropriate surgical choice and defining the correct systemic treatment tailored to each clinical condition.

Dynamic Modulated Brachytherapy (DMBT) Balloon Applicator for Accelerated Partial Breast Irradiation

PURPOSE

To propose a novel high-dose-rate brachytherapy applicator for balloon-based dynamic modulated brachytherapy (DMBT) for accelerated partial breast irradiation (APBI) and to demonstrate its dosimetric advantage compared to the widely used Contura applicator.

METHODS AND MATERIALS

The DMBT balloon device consists of a fixed central channel enabling real-time, in vivo dosimetry and an outer motion-dynamic, adjustable-radius channel capable of moving to any angular position within the balloon. This design allows placement of dwell positions anywhere within the balloon volume, guaranteeing optimal placement and generation of the applicator and treatment plan, respectively. Thirteen clinical treatment plans for patients with early-stage breast cancer receiving APBI after lumpectomy using Contura were retrospectively obtained under institutional review board approval. New treatment plans were created by replacing the Contura with the DMBT device. DMBT plans were limited to 4 angular positions and an outer channel radius of 1.5 cm. The new plans were optimized to limit dose to ribs and skin while maintaining target coverage similar to that of the clinical plan.

RESULTS

Similar target coverage was obtained for the DMBT plans compared with clinical Contura plans. Across all patients the mean (standard deviation) reductions in D0.1 cc to the ribs and skin were 6.70% (6.28%) and 5.13% (6.54%), respectively. A threshold separation distance between the balloon surface and the organ at risk (OAR), below which dosimetric changes of greater than 5% were obtained, was observed to be 12 mm for ribs and skin. When both OARs were far from the balloon, DMBT plans were of similar quality to Contura plans, as expected.

CONCLUSIONS

This study demonstrates the superior ability of the APBI DMBT applicator to spare OARs while achieving target coverage comparable to current treatment plans, especially when in close proximity. The DMBT balloon may enable new modes of dynamic high-dose-rate treatment delivery and allow for ultrahypofractionated dose regimens to be safely used.

Six-Year Results From a Phase I/II Trial for Hypofractionated Accelerated Partial Breast Irradiation Using a 2-Day Dose Schedule

BACKGROUND

To report 6-year outcomes from a phase I/II trial using balloon-based brachytherapy to deliver APBI in 2 days.

METHODS

A total of 45 patients with early-stage breast cancer received adjuvant APBI in 2 days with high-dose rate (HDR) brachytherapy totaling 2800 cGy in 4 fractions (700 cGy BID) using a balloon-based applicator as part of a prospective phase I/II clinical trial. All patients had negative margins and skin spacing ≥8 mm. We evaluated toxicities (CTCAE v3) as well as ipsilateral breast tumor recurrence (IBTR), regional nodal failure (RNF), distant metastasis, disease-free survival, cause-specific survival, and overall survival.

RESULTS

Median age and tumor size were 66 years old (48 to 83) and 0.8 cm (0.2 to 2.3 cm), respectively. Four percent of patients were N1 (n=2) and 73% were estrogen receptor (ER) positive (n=32). Median follow-up was 6.2 years (2.4 to 8.0 y). Nearly all toxicities at 6 years were grade 1 to 2 except 1 instance of grade 3 telangiectasia (2%). Eleven percent (n=5) of patients had chronic asymptomatic fat necrosis whereas asymptomatic seromas were noted on mammogram in 13% of cases (n=6). Cosmesis at last follow-up was good or excellent in 91% of cases (n=40) and fair in 9% (n=4). Two of the previously reported rib fractures healed with conservative measures. There were no IBTR or RNF (6 y IBTR/RNF rate 0%); however, 2 patients experienced distant metastasis (4% at 6 y). The 6-year actuarial disease-free survival, cause-specific survival, and overall survival were 96%, 100%, and 93%, respectively.

CONCLUSIONS

Hypofractionated 2-day APBI using brachytherapy resulted in excellent clinical outcomes with acceptable chronic toxicities.

Partial versus whole breast irradiation: Side effects, patient satisfaction and costs

PURPOSE

Since accelerated partial breast irradiation has demonstrated non-inferiority to whole breast irradiation regarding recurrence rate in patients with early stage breast cancer, our objective was to compare its impact on short-term adverse events, patient satisfaction and costs.

MATERIALS AND METHODS

Patients with early stage breast cancer treated by breast-conserving surgery between 2007 and 2012 were included: 48 women who received three-dimensional conformal accelerated partial breast irradiation in a multicentre phase-II trial were paired with 48 patients prospectively treated with whole breast irradiation. Adverse events, and patients' opinions concerning cosmesis, satisfaction and pain, were gathered 1 month after treatment. Direct and indirect costs were collected from the French National Health Insurance System perspective until the end of radiotherapy.

RESULTS

When comparing its impact, skin reactions occurred in 37% of patients receiving three-dimensional conformal accelerated partial breast radiotherapy and 60% of patients receiving whole breast irradiation (P=0.07); 98% were very satisfied in the group three-dimensional conformal accelerated partial breast radiotherapy versus 46% in the group treated with whole breast irradiation (P<0.001); direct costs were significantly lower in the group treated with partial breast irradiation (mean cost: 2510€ versus 5479€/patient), due to less radiation sessions.

CONCLUSION

In patients with early-stage breast cancer, partial irradiation offered a good alternative to whole breast irradiation, as it was less expensive and satisfactory. These, and the clinical safety and tolerance results, need to be confirmed by long-term accelerated partial breast irradiation results in on-going phase III trials.

Effectiveness of different accelerated partial breast irradiation techniques for the treatment of breast cancer patients: Systematic review using indirect comparisons of randomized clinical trials

AIM

This systematic review was conducted to compare the effectiveness of different accelerated partial breast irradiation (APBI) techniques for the treatment of breast cancer patients.

BACKGROUND

Numerous (APBI) techniques are available for clinical practice.

METHODS AND MATERIALS

Systematic review of randomized controlled trials of APBI versus whole breast irradiation (WBI). The data from APBI studies were extracted for the analyses. Indirect comparisons were used to compare different APBI techniques.

RESULTS

Ten studies fulfilled the inclusion criteria. A total of 4343 patients were included, most of them with tumor stage T1-T2 and N0. Regarding APBI techniques, six trials used external beam radiation therapy; one intraoperative electrons; one intraoperative low-energy photons; one brachytherapy; and one external beam radiation therapy or brachytherapy. The indirect comparisons related to 5-years local control and 5-years overall survival were not significantly different between APBI techniques.

CONCLUSIONS

Based on indirect comparisons, no differences in clinical outcomes were observed among diverse APBI techniques in published clinical trials that formally compared WBI to APBI. However wide confidence intervals and high risk of inconsistency precluded a sound conclusion. Further head-to-head clinical trials comparing different APBI techniques are required to confirm our findings. Studies comparing different techniques using individual participant data and/or real-life data from population-based studies/registries could also provide more robust results.

Post-implant analysis in permanent breast seed implant: automated plan reconstruction using simulated annealing

Purpose

Post-implant analysis in permanent breast seed implant (PBSI) brachytherapy is an important component of the quality assurance process that indicates dosimetric quality relevant to patient outcome, indicating salvage therapy if inadequate, as well as providing feedback to the brachytherapy team to improve future treatments. To measure geometric indices on implant quality, plan reconstruction must be performed to correlate each planned and post-implant seed location. In this work, a simulated-annealing-based algorithm is developed to perform this plan reconstruction automatically.

Material and methods

The plan reconstruction algorithm was developed in MATLAB, taking the patient pre-treatment and post-implant (Day 0) plan and associated contours as inputs. For 19 treated patients, a reconstruction was obtained that defined the correspondence between each planned and post-implant seed. The simulated-annealing algorithm was used to reconstruct each patient 10 times to assess the variability in convergence. Manual reconstructions performed by at least two independent observers to obtain consensus were defined as the ground truth; these were compared to the automatic reconstructions obtained by the algorithm. Metrics on seed placement accuracy and needle strand angulation were calculated for the patients.

Results

The algorithm performed reconstructions on 19 patients (1235 seeds) with ground-truth reconstructions, obtaining 97 ± 8% correct matches. This strong performance indicates the ability to incorporate this algorithm into the clinical quality assurance workflow.

Conclusions

The plan reconstruction algorithm developed herein performed very well in a 19-patient cohort. This algorithm can be incorporated into the clinical process to assist in the assessment of center-specific seed placement accuracy and can be used to gather implant metrics in an automated, standardized fashion for future PBSI trials.

Ductal carcinoma in situ and intraoperative partial breast irradiation: Who are the best candidates? Long-term outcome of a single institution series

AIMS

To report the long-term outcome of a single institution series of pure ductal carcinoma in situ (DCIS) treated with accelerated partial irradiation using intraoperative electrons (IOERT).

METHODS

From 2000 to 2010, 180 DCIS patients, treated with quadrantectomy and 21 Gy IOERT, were analyzed in terms of ipsilateral breast recurrences (IBRs) and survival outcomes by stratification in two subgroups. The low-risk group included patients who fulfilled the suitable definition according to American Society of Radiation Oncology (ASTRO) Guidelines (size ≤2.5 cm, grade 1-2 and surgical margins ≥3 mm) (Suitable), while the remaining ones formed the high-risk group (Non-Suitable).

RESULTS

Eighty-four and 96 patients formed the Suitable and Non-Suitable groups, respectively. In the whole population, the cumulative incidence of IBR at 5, 7 and 10 years was 19%, 21%, and 25%, respectively. In the Suitable group, the cumulative incidence of IBR remained constant at 11% throughout the years, while in the Non-Suitable group increased from 26% at 5 years to 36% at 10 years (p < 0.0001). When hormonal positivity and HER2 absence of expression were added to the selection of the Suitable group, the cumulative incidence of IBR dropped and stabilized at 4% at 10 years. None died of breast cancer. In the whole population, 5-year and 10-year overall survival rate was 98% and 96.5%, respectively, without any difference between the two groups.

CONCLUSIONS

The overall and by group IBR rates were high and stricter criteria are required for acceptable local control for Suitable DCIS. Because of the concerns raised, IOERT should not be used in clinical practice.

Long-term results of multicatheter interstitial high-dose-rate brachytherapy for accelerated partial-breast irradiation

PURPOSE

The purpose of this study was to report the long-term results of women treated in one center with accelerated partial-breast irradiation (APBI) with interstitial high-dose-rate (HDR) brachytherapy.

MATERIALS AND METHODS

We analyzed data from women treated in one center with adjuvant interstitial HDR brachytherapy for early-stage breast cancer. Treatment regimen was homogeneous for all women with treatment dose 32Gy in 8 fractions twice daily given to the tumor bed with interstitial HDR brachytherapy.

RESULTS

About 364 women were treated with interstitial HDR brachytherapy as APBI from March 2000 to March 2014. Mean age at diagnosis was 62 years. Stage distribution was as follows: T1a = 12%, T1b = 33%, T1c = 40%, T2 = 14%, and Tis = 1%. 97% of patients were N0. 88% had invasive ductal carcinoma. 86% had positive hormone receptor status. 14 ipsilateral breast tumor recurrences were identified with 12 deemed local recurrences and 2 deemed to be second ipsilateral primaries. Actuarial 5-year and 10-year overall survival rates were 95.1% and 92.2%, respectively. Actuarial 5-year and 10-year local relapse-free survival rates were 96.2% and 88.8%, respectively.

CONCLUSIONS

The results of this previously unreported series of women treated with a homogeneous APBI method exclusively with interstitial HDR brachytherapy present further data justifying that in appropriately selected women, APBI with interstitial brachytherapy provides rates of local control and survival comparable with whole-breast irradiation.

Injection of radiopaque hydrogel at time of lumpectomy improves the target definition for adjuvant radiotherapy

BACKGROUND AND PURPOSE

During oncoplastic breast-conserving surgery (BCS), the surgical cavity is closed to reduce seroma formation. This makes the radiotherapy target definition using clips challenging, leading to poor inter-observer agreement and potentially geographical misses. We hypothesize that injecting a radiopaque hydrogel in the lumpectomy cavity before closure improves radiotherapy target definition and agreement between observers.

MATERIALS AND METHODS

Women undergoing BCS in a single university hospital were prospectively accrued in the study. Three to 9 ml of iodined PolyEthylene Glycol (PEG) hydrogel and clips were inserted in the lumpectomy cavity. A CT-scan was performed at 4 to 6 weeks. CT images of BCS patients with standard clips only were used as control group, matched on age, specimen weight, and distance between clips. Six radiation oncologists delineated the tumor bed volumes and rated the cavity visualization scores (CVS). The primary endpoint was the agreement between observers measured using a Conformity Index (Cx).

RESULTS

Forty-two patients were included, 21 hydrogel procedures and 21 controls, resulting in 315 observer pairs. The feasibility of the intervention was 100%. The median Cx was higher in the intervention group (Cx = 0.70, IQR [0.54-0.79]) than in the control group (Cx = 0.54, IQR [0.42-0.66]), p < 0.00, as were the CVS (3.5 [2.5-4.5] versus 2.5 [2-3.5], p < 0.001). The rate of surgical site infections was similar to literature.

CONCLUSIONS

The use of radiopaque PEG enables to identify the lumpectomy cavity, resulting in a high inter-observer agreement for radiotherapy target definition. This intervention is easy to perform and blend well into current practice.

Accelerated partial breast irradiation with perioperative multicatheter interstitial brachytherapy-A feasibility study

PURPOSE

To assess the feasibility of high-dose-rate perioperative multicatheter interstitial brachytherapy to deliver accelerated partial breast irradiation (APBI) in selected patients with early breast cancer.

METHODS AND MATERIALS

Perioperative multicatheter interstitial brachytherapy for APBI has been used at our department since 2012 for patients with low-risk breast cancer. Interstitial catheters were inserted perioperatively via hollow needles immediately following tumorectomy with sentinel node biopsy. APBI started on Day 6 after surgery. The prescribed dose was 34 Gy (10 fractions of 3.4 Gy bid). Hormonal therapy was prescribed in all cases.

RESULTS

Between June 2012 and December 2017, 125 patients were scheduled for APBI. Of these, APBI was not performed in 12 patients (9.6%) due to adverse prognostic factors identified on the definitive biopsy. We observed wound dehiscence in 2/113 cases (1.8%), inflammatory complications requiring antibiotics in 7/113 cases (6.2%), transient Grade I radiodermatitis in 6/113 patients (4.4%), and seroma which resolved spontaneously in 3/113 patients (2.7%). With median followup of 39 months (range 3.3-75.3) no relapses were observed. No late complications in Radiation Therapy Oncology Group Grade 3 or higher were documented. Cosmetic outcome in patients with followup > 2 years was excellent or good in 92%.

CONCLUSION

Our preliminary results show that the perioperative multicatheter interstitial high-dose-rate brachytherapy for APBI in selected patients with early breast cancer is feasible. This treatment schedule reduces treatment duration, spares the patients of repeated anesthesia, and enables precise application of the afterloading tubes under direct visual control.

Preliminary toxicity results using partial breast 3D-CRT with once daily hypo-fractionation and deep inspiratory breath hold

BACKGROUND

To evaluate the clinical outcomes of patients treated with 3D conformal Hypo-fractionated, deep Inspiratory breath-hold (DIBH), Partial breast radiotherapy, termed "HIP." HIP was implemented to merge the schedule of once-daily breast hypofractionation with partial breast treatment.

METHODS

We identified 38 breast cancers in 37 patients from 2013 to 2014 treated at our institution with HIP following lumpectomy for early stage breast cancer. Patients received a hypo-fractionated course (≤ 20 fractions) of once daily radiation to the partial breast (lumpectomy cavity + margin) utilizing DIBH regardless of laterality. Clinical and treatment-related characteristics were obtained, including target volume and organ at risk (OAR) dosimetric characteristics. Patients were followed clinically and with at least yearly mammograms for up to 36 months (range 5-36 months). Acute and late toxicity was scored using the Common Terminology Criteria for Adverse Events (CTCAE) v4.03.

RESULTS

Patients received a median dose of 42.56 Gy in 16 Fractions (Fx) (range 40.05-53.2 Gy; and 15-20 Fx). OAR doses were low, with a mean heart dose of 0.37 Gy, an ipsilateral lung V20 mean of 4%, and a contralateral lung V5 of 1%. Acute toxicity (≤ grade 2) was present in 79% (n = 30) of the cases, with dermatitis being the most common finding (63%). Late grade 1-2 toxicity was present in 42% (n = 16) of the cases, with hyperpigmentation being the most common finding (n = 9). There were no severe acute or late toxicities (≥ grade 3). At a median follow up of 21 months, there were no local, regional, or distant failures.

CONCLUSIONS

We report limited toxicity in this low risk cohort of patients with early stage breast cancer treated with HIP, a unique and logical combination of 3-D conformal external beam radiotherapy, moderate hypo-fractionation, and DIBH.

Inverse planning and inverse implanting for breast interstitial brachytherapy. Introducing a new anatomy specific breast interstitial template (ASBIT)

An innovative template, based on thoracic cage surface reconstructions for breast interstitial brachytherapy was developed. Hybrid-inverse-planning-optimisation-based implantations and brachytherapy plans, using three custom anthropomorphic breast phantoms, were utilised for its validation. A user independent, inverse planning and inverse implanting technique is proposed.

ESTRO-ACROP guideline: Interstitial multi-catheter breast brachytherapy as Accelerated Partial Breast Irradiation alone or as boost - GEC-ESTRO Breast Cancer Working Group practical recommendations

PURPOSE

This consensus statement from the Breast Cancer Working Group of Groupe Européen de Curiethérapie of European Society for Radiotherapy and Oncology (GEC-ESTRO) aims at generating practical guidelines for multi-catheter image-guided brachytherapy in the conservative management of breast cancer patients used for either Accelerated Partial Breast Irradiation (APBI) or for a breast boost.

METHODS

Recent advances in techniques of multi-catheter brachytherapy were summarized and all the relevant literature was reviewed by a panel of experts. Panel members of the GEC-ESTRO experts participated in a series of conferences, supplemented their clinical experience, were surveyed to determine their current practices and patterns, performed a literature review, and formulated recommendations for implementing APBI with multi-catheter brachytherapy, focusing on treatment planning issues, catheter insertion, dosimetry and quality assurance. This document was reviewed and approved by the full panel, the GEC-ESTRO executive board and by the ACROP (Advisory Committee on Radiation Oncology Practice).

RESULTS

Three-dimensional (3D) treatment planning, catheter insertion techniques, dosimetry and methods of quality assurance for APBI and boost with multi-catheter image-guided brachytherapy after breast conserving surgery are described. Detailed recommendations for daily practice including dose constraints are given.

CONCLUSIONS

Recent standards and guidelines for the use of APBI with different multi-catheter image-guided brachytherapy techniques have been defined. Different techniques are used to insert the catheters. Guidelines are mandatory to assure precise catheter insertion for coverage of the target volume and to guarantee high-quality dosimetry. The same rules apply for brachytherapy based boost irradiation for breast cancer after whole breast irradiation as well as for partial breast re-irradiation.

Should molecular subtype be recommended as one of the selection criteria for accelerated partial breast irradiation? Preliminary results from an Asian cohort

Purpose

The purpose of this study was to report clinical outcomes in patients treated with accelerated partial breast irradiation (APBI), stratified as per molecular subtype and American Society for Therapeutic Radiology and Oncology/Groupe Européen de Curiethérapie and European Society for Radiotherapy & Oncology (ASTRO/GEC-ESTRO) patient selection criteria in order to determine whether molecular subtype should be recommended as one of the selection criteria for APBI.

Material and methods

157 early-stage breast cancers patients, treated with APBI using multi-catheter interstitial brachytherapy with ≥ 6 months follow-up were included. Molecular subtype was assigned based on estrogen/progesterone receptor (ER/PR), Her2neu and tumor grade. Patients were stratified into ASTRO and GEC-ESTRO risk groups, as per updated ASTRO consensus statement (CS) and GEC-ESTRO recommendation, respectively. The Kaplan-Meier method was used to calculate the time to event data of clinical outcomes.

Results

With a median follow-up of 35 months, local control (LC) and locoregional control (LRC) were not significantly different among the different molecular subtypes (p = 0.19, p = 0.41, respectively). None of the APBI guidelines predicted risk of local or locoregional recurrence. Re-analyzing the data by replacing ER status with molecular subtype in the ASTRO-CS did not show any significant difference in LC/LRC across the various categories. Her2neu subtype was associated with significantly lower disease-free survival, cause specific survival, and overall survival than the luminal subtypes.

Conclusions

None of the mentioned APBI guidelines predicted local or locoregional recurrence risk in our study population. Additional follow-up will be needed to recommend inclusion of molecular subtype (or at least HER2 receptor status) in the patient selection criteria for APBI.

Outcomes by molecular subtype after accelerated partial breast irradiation using single-entry catheters

PURPOSE

Tumor biology is being recognized as an important indicator of prognosis and risk of locoregional recurrence. Here, we determine actuarial recurrence rates by approximated molecular subtype for women treated with single-entry catheter accelerated partial breast irradiation (sAPBI).

METHODS AND MATERIALS

One thousand four hundred eighty-six women with invasive cancer having known ER, PR, and Her2 status and at least 1-year of followup were treated using MammoSite, Contura, or SAVI sAPBI from 2002 to 2014 at our institution. Actuarial recurrence rates were determined for the following four approximated molecular subtypes using the Kaplan-Meier method: luminal A (n = 1081), luminal B (n = 164), Her2 (n = 123), and triple-negative breast cancer (TNBC; n = 118).

RESULTS

With a median followup time of 3.3 years (range 1-13.6 years), the 5-year in-breast tumor recurrence rate was 2.6% overall, 2.1% for luminal A, 1.5% for luminal B, 4.9% for Her2, and 5.4% for TNBC. Luminal A and B subtypes, as compared with the more aggressive Her2 and TNBC subtypes combined, demonstrated lower 5-year in-breast tumor recurrence (2.1% vs. 5.1%, p = 0.021). The 5-year regional nodal recurrence rate was 1.4% overall, 1.4% for luminal A, 0% for luminal B, 1% for Her2, and 4.2% for TNBC. The 5-year locoregional control is 97.3% for luminal breast cancers and 93.8% for the more aggressive Her2 and TNBC subtypes collectively.

CONCLUSIONS

Luminal cancers demonstrated excellent 5-year locoregional control with sAPBI. Although caution should be used when treating patients with the more aggressive Her2 and TNBC subtypes, these subtypes have demonstrated higher LRR with mastectomy and whole-breast irradiation. Further randomized comparisons are needed to determine the optimal treatment for these higher risk patients.

A multi-institutional analysis of intraoperative radiotherapy for early breast cancer: Does age matter?

BACKGROUND

Single-session intraoperative radiation therapy (IORT) minimizes treatment demands associated with traditional whole breast radiation therapy (WBRT) but outcomes on local disease control and morbidity among the elderly is limited.

METHODS

A multi-institutional retrospective registry was established from 19 centers utilizing IORT from 2007 to 2013. Patient, tumor, and treatment variables were analyzed for ages <70 and ≥70.

RESULTS

We evaluated 686 patients (<70 = 424; ≥70 = 262) who were margin and lymph node negative. Patients <70 were more likely to have longer operative time, oncoplastic closure, higher rates of IORT used as planned boost, and receive chemotherapy and post-operative WBRT. Wound complication rates were low and not significantly different between age groups. Median follow-up was 1.06 (range 0.51-1.9) years for < 70 and 1.01 (range 0.5-1.68) years for ≥ 70. There were 5 (0.73%) breast recurrences (4 in <70 and 1 ≥ 70, p = 0.65) and no axillary recurrences during follow-up.

CONCLUSIONS

IORT was associated with a low rate of wound complication and local recurrence on short-term follow-up in this cohort.