Prospective Comparison of Toxicity and Cosmetic Outcome After Accelerated Partial Breast Irradiation With Conformal External Beam Radiotherapy or Single-Entry Multilumen Intracavitary Brachytherapy

Partial Breast Irradiation for Patients With Early-Stage Invasive Breast Cancer or Ductal Carcinoma In Situ: An ASTRO Clinical Practice Guideline

PURPOSE

This guideline provides evidence-based recommendations on appropriate indications and techniques for partial breast irradiation (PBI) for patients with early-stage invasive breast cancer and ductal carcinoma in situ.

METHODS

ASTRO convened a task force to address 4 key questions focused on the appropriate indications and techniques for PBI as an alternative to whole breast irradiation (WBI) to result in similar rates of ipsilateral breast recurrence (IBR) and toxicity outcomes. Also addressed were aspects related to the technical delivery of PBI, including dose-fractionation regimens, target volumes, and treatment parameters for different PBI techniques. The guideline is based on a systematic review provided by the Agency for Healthcare Research and Quality. Recommendations were created using a predefined consensus-building methodology and system for grading evidence quality and recommendation strength.

RESULTS

PBI delivered using 3-dimensional conformal radiation therapy, intensity modulated radiation therapy, multicatheter brachytherapy, and single-entry brachytherapy results in similar IBR as WBI with long-term follow-up. Some patient characteristics and tumor features were underrepresented in the randomized controlled trials, making it difficult to fully define IBR risks for patients with these features. Appropriate dose-fractionation regimens, target volume delineation, and treatment planning parameters for delivery of PBI are outlined. Intraoperative radiation therapy alone is associated with a higher IBR rate compared with WBI. A daily or every-other-day external beam PBI regimen is preferred over twice-daily regimens due to late toxicity concerns.

CONCLUSIONS

Based on published data, the ASTRO task force has proposed recommendations to inform best clinical practices on the use of PBI.

A postimplant dosimetry simulation framework for robustness evaluation in permanent breast seed implant brachytherapy

BACKGROUND

Permanent breast seed implant (PBSI) brachytherapy is a promising treatment that has the potential to be widely utilized with increased standardization, optimization, and robustness. Excellent early efficacy and very high patient acceptance were reported, however, to further evaluate and improve planning strategies, a framework to quantify plan robustness to implant uncertainties is necessary.

PURPOSE

In this study, we aim to quantify clinical seed displacement using an automated algorithm and develop and validate a PBSI post-implant dosimetry simulation framework to evaluate PBSI plan robustness to implant uncertainties.

METHODS AND MATERIALS

Clinical PBSI seed displacements were quantified for 63 consecutive patients. A PBSI simulator was developed in Matlab (2020) by resampling clinical seed displacements and computing a range of possible post-implant dosimetry outcomes under various seed displacement scenarios. Simulations were performed retrospectively on 63 previous clinical plans to evaluate plan robustness to seed displacement.

RESULTS

Mean seed displacement for the whole cohort was 10 ± 6 mm. A clinical seed displacement database was established and a user interface was developed for the simulation framework. For all clinical plans, the median (range) value of simulated median ETV V90 in various seed displacement scenarios was 97.8% (87.5-100%).

CONCLUSIONS

A PBSI postimplant dosimetry simulation framework was developed and validated. Simulation results showed that the current PTV planning margin is sufficient to provide adequate postimplant dose coverage of ETV. This simulator can be used to evaluate plan robustness to seed displacement and will facilitate future research in improving PBSI planning methods.

Partial breast irradiation compared with whole breast irradiation: a systematic review and meta-analysis

BACKGROUND

Early-stage breast cancer is among the most common cancer diagnoses. Adjuvant radiotherapy is an essential component of breast-conserving therapy, and several options exist for tailoring its extent and duration. This study assesses the comparative effectiveness of partial-breast irradiation (PBI) compared with whole-breast irradiation (WBI).

METHODS

A systematic review was completed to identify relevant randomized clinical trials and comparative observational studies. Independent reviewers working in pairs selected studies and extracted data. Randomized trial results were pooled using a random effects model. Prespecified main outcomes were ipsilateral breast recurrence (IBR), cosmesis, and adverse events (AEs).

RESULTS

Fourteen randomized clinical trials and 6 comparative observational studies with 17 234 patients evaluated the comparative effectiveness of PBI. PBI was not statistically significantly different from WBI for IBR at 5 years (RR = 1.34, 95% CI = 0.83 to 2.18; high strength of evidence [SOE]) and 10 years (RR = 1.29, 95% CI = 0.87 to 1.91; high SOE). Evidence for cosmetic outcomes was insufficient. Statistically significantly fewer acute AEs were reported with PBI compared with WBI, with no statistically significant difference in late AEs. Data from subgroups according to patient, tumor, and treatment characteristics were insufficient. Intraoperative radiotherapy was associated with higher IBR at 5, 10, and over than 10 years (high SOE) compared with WBI.

CONCLUSIONS

Ipsilateral breast recurrence was not statistically significantly different between PBI and WBI. Acute AEs were less frequent with PBI. This evidence supports the effectiveness of PBI among selected patients with early-stage, favorable-risk breast cancer who are similar to those represented in the included studies.

Factors Associated With Cosmetic Outcomes After Treatment With a Novel Form of Breast Intraoperative Radiation Therapy

INTRODUCTION

Precision breast intraoperative radiation therapy (PB-IORT) incorporates computed tomography-guided treatment planning and high dose rate brachytherapy to deliver a single dose of highly conformal radiational therapy. The purpose of this study is to determine factors associated with poor cosmetic outcomes after treatment with PB-IORT.

METHODS

The study included all consecutive participants enrolled in an ongoing phase II clinical trial that had completed a minimum of 12 mo of follow-up. A poor cosmetic outcome was defined as scoring "fair" or "poor" on the Harvard Cosmesis evaluation, or "some" or "very much" on any of the three general cosmesis categories. Statistical analysis was performed utilizing R.

RESULTS

The final cohort included 201 participants, of which 181 (90%) had an overall good/excellent cosmetic outcome. Group 1 consisted of 162 (81%) participants who reported only excellent/good cosmetic outcomes. Group 2 consisted of 39 (19%) participants who reported some aspect of a poor cosmetic outcome. On multivariable analysis, participants with ductal carcinoma in situ were significantly more likely to experience a poor cosmetic outcome (odds ratio 2.45, 95% confidence interval 1.03-5.82, P = 0.04), and those who received subsequent whole breast irradiation were also more likely to have a poor cosmetic outcome (odds ratio 10.20, 95% confidence interval CI 1.04-99.95, P = 0.04).

CONCLUSIONS

Patients with need for further radiation after PB-IORT are at increased risk for a poor cosmetic outcome. Larger balloon volume and distance between the skin do not have deleterious effects on cosmetic outcomes.

Delivery of Adjuvant Radiation in 5 Days or Less After Lumpectomy for Breast Cancer: A Systematic Review

BACKGROUND

Recent data have been published supporting the application of ultra-short radiation therapy (RT) regimens for women with early stage breast cancer following breast conserving surgery (BCS). What has remained controversial is whether and how to apply accelerated whole breast irradiation (AWBI) or accelerated partial breast irradiation (APBI) approaches in these patients, as well as the consideration of intraoperative RT (IORT) for this population.

METHODS

We performed a systematic review of the literature searching for randomized and prospective data published evaluating ultra-short RT delivered in 5-days or less with APBI, AWBI, or IORT.

RESULTS

We identified two randomized studies applying AWBI (n=5,011 patients) with 5 to 10 year follow up, which supported the use of ultra-short course AWBI (5 fractions in one week) as compared to hypofractionated WBI. We identified six randomized trials evaluating APBI (as compared to WBI) in 5 days or less (n= 8,415) with numerous (n=55) prospective studies as well, with the data supporting short course APBI as compared to WBI. Finally, we identified two randomized trials evaluating IORT; however, both trials demonstrated elevated rates of recurrence with IORT as compared to WBI.

CONCLUSIONS

The current body of data available for ultra-short adjuvant RT regimens delivered in 5-days or less after BCS overwhelming support their utilization. While data for both exists, APBI regimens have, by far, greater numbers of patients and longer follow-up as compared to AWBI. Also, given increased rates of recurrence seen with IORT with long-term follow-up, this should not be considered a standard approach at this time.

Accelerated partial breast irradiation with 3-dimensional conformal and image-guided intensity-modulated radiotherapy following breast conserving surgery - 7-Year results of a phase II trial

Purpose

To present the 7-year results of accelerated partial breast irradiation (APBI) using three-dimensional conformal (3D-CRT) and image-guided intensity-modulated radiotherapy (IG-IMRT) following breast-conserving surgery (BCS).

Patients and methods

Between 2006 and 2014, 104 patients were treated with APBI given by means of 3D-CRT using 3–5 non-coplanar, isocentric wedged fields, or IG-IMRT using kV-CBCT. The total dose of APBI was 36.9 Gy (9 × 4.1 Gy) using twice-a-day fractionation. Survival results, side effects and cosmetic results were assessed.

Results

At a median follow-up of 90 months three (2.9%) local recurrences, one (0.9%) regional recurrence and two (1.9%) distant metastases were observed. The 7-year local (LRFS), recurrence free survival was 98.9%. The 7-year disease-free (DFS), metastases free (MFS) and overall survival (OS) was 94.8%, 97.9% and 94.8%, respectively. Late side effects included G1 skin toxicity in 15 (14.4%), G1, G2, and G3 fibrosis in 26 (25%), 3 (2.9%) and 1 (0.9%) patients respectively. Asymptomatic (G1) fat necrosis occurred in 10 (9.6%) patients. No ≥ G2 or higher late side effects occurred with IMRT. The rate of excellent/good and fair/poor cosmetic results was 93.2% and 6.8%, respectively.

Conclusion

7-year results of APBI with 3D-CRT and IG-IMRT are encouraging. Toxicity profile and local tumor control are comparable to other series using multicatheter interstitial brachytherapy. Therefore, these external beam APBI techniques are valid alternatives to whole breast irradiation and brachytherapy based APBI.

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Phase II APBI trial using 3D-CRT or IG-IMRT.

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Twice-a-day fractionation, with a total dose of 36.9 Gy (9 × 4.1Gy).

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No Grade 2 or worst late side effects with IG-IMRT at median follow up of 90 months.

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These APBI techniques are valid alternatives to WBI or brachytherapy based APBI.

Defining dose constraints for catheter insertion sites to minimize toxicity after interstitial breast brachytherapy

PURPOSE

The purpose of this study was to define dose constraints for catheter insertion sites to minimize probability of prominent post-therapy skin marks after interstitial breast brachytherapy.

METHODS AND MATERIALS

Forty patients who had undergone interstitial breast brachytherapy were studied at followup at least 2 years after the procedure. Their implant marks were compared with background skin and areola and scored as Gr0 = invisible (same color as surrounding skin), Gr1 = darker than surrounding skin but lighter than areola or hypopigmentation, and Gr2 = same color as areola or darker. Highest point doses received in each plane of implant and their corresponding closest distances from clinical target volume, 85% isodose, and closest catheter dwell point were used for analysis. A logistic regression was performed to ascertain effects of various dosimetric parameters on the probability of Gr2 marks. Receiver operating characteristic curve was generated to derive cutoffs.

RESULTS

A total of 280 dose points were studied. Median values for various parameters were 1.4 Gy (0.24-3.74) for Dose max and 1.6 cm, 1.5 cm, and 1.0 cm for Dist CTV min, Dist Iso min, and Dist Dwell min, respectively. On logistic regression, increasing Dose max alone was associated with an increased likelihood of developing Gr2 marks. Each unit increase of Dose max increased probability of development of Gr2 skin marks by 5.0% (2.391-10.328). Receiver operating characteristic analysis also showed greatest odd ratio (8.0), sensitivity (74.8%), and specificity (73%) for Dose max.

CONCLUSIONS

It seems prudent to restrict dose to catheter insertion sites for better cosmesis.

Modern development of high-dose-rate brachytherapy

Brachytherapy is an invasive therapy with placement of radiation source into or near the tumor. The difference between planning target volume and clinical target volume is minimal, and the dose out of the tumor reduces rapidly due to the inverse-square law. High-dose-rate brachytherapy enables three-dimensional image guidance, and currently, tumor dose as well as doses of the surrounding normal structures can be evaluated accurately. High-dose-rate brachytherapy is the utmost precision radiation therapy even surpassing carbon ion therapy. Biological disadvantages of high-dose rate have been overcome by the fractional irradiation. High-dose-rate brachytherapy is indispensable in the definitive radiation therapy of cervical cancer. Also in prostate cancer and breast cancer, high-dose-rate brachytherapy plays a significant role. Brachytherapy requires techniques and skills of radiation oncologists at the time of invasive placement of the radiation source into the tumor area. Education of young radiation oncologists is most urgent and important.

Analysis of breast cosmetic effects 3 years after breast-conserving surgery and intraoperative radiotherapy with and without adjuvant whole breast irradiation

INTRODUCTION

Intraoperative radiotherapy (IORT) based on low-kV photons may be an option for early breast cancer patients. Following Targit trial results some of those patients should undergo whole breast irradiation (WBRT) additionally.

MATERIAL AND METHODS

Since April 2010, IORT has been applied to early breast cancer patients. One hundred and fifty patients were prospectively followed up and examined to evaluate the side effects (pain, fibrosis, breast edema, telangiectasias). We present the results 3 years post-treatment. WBRT was given to 82 (54.7%) patients.

RESULTS

Tumor cavity fibrosis grade II and more was observed in 18 (12%) patients, as grade III only in 2 (1.33%) patients. Breast tissue fibrosis outside tumor cavity grade II was observed only in 2 (1.33%) patients. Breast edema was present in 10 (6.66%) patients. WBRT administration led to increased frequency of higher grade tumor cavity fibrosis (P < .0001), breast fibrosis (P < .0001), breast edema (P = .003), and occurrence of telangiectasias (P = .03), with no influence on pain reported by patients. In case of WBRT, tumor location (P = .026) and size of the irradiated breast (P = .015) were independent risk factors for higher degree of breast fibrosis, as seroma evacuation 6 months post-WBRT (P = .036) was the only independent risk factor for higher level of tumor cavity fibrosis in multiple regression.

CONCLUSIONS

The cosmetic result after IORT is good and comparable to other accelerated partial breast irradiation techniques. Administration of WBRT post-IORT in breast cancer patients increases the level of fibrotic changes, breast edema and telangiectasias 3 years post-treatment, but with no influence on pain.

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.

Cosmetic assessment in brachytherapy (interventional radiotherapy) for breast cancer: A multidisciplinary review

PURPOSE

This review was to focus on breast brachytherapy cosmetic assessment methods state of the art and to define the advantages and disadvantages related to.

METHODS AND MATERIALS

We conducted a literature review of the major experience on breast brachytherapy cosmetic assessment methods in several databases (PubMed, Scopus, and Google Scholar databases). To identify the relevant works, a task force screened citations at title and abstract level to identify potentially relevant paper. An expert board reviewed and approved the text. The assessment systems were classified into three main groups: (1) the Oncological Toxicity Scales, (2) the Independent Patients Perspective Measures, (3) the Patient-Related Outcome Measures. Each cosmetic assessment method was evaluated following six parameters: (1) anatomical site, (2) advantages, (3) disadvantages, (4) subjective/objective, (5) quantitative/qualitative, (6) computers or pictures needs.

RESULTS

Eleven assessment methods were selected. Three methods were classified as Oncological Toxicity Scale, six in the Independent Patients Perspective Measures classification, and two as Patient-Related Outcome Measures. Six methods are subjective, while eight are objective. Four systems are classified as quantitative, four as qualitative while three both. Five systems need informatics support. Moreover, each method was discussed individually reporting the main characteristics and peculiarities.

CONCLUSIONS

Cosmesis is one major end point for the patient who has a malignancy of low lethal potential. In modern personalized medicine, there is a need for standardized cosmetic outcome assessments to analyze and compare the results of treatments. No gold standard methods currently exist. The result of this review is to summarize the various cosmesis methods, defining the strengths and weaknesses of each one and giving a line in research and clinical practice.