Brachytherapy-based partial breast irradiation is associated with low rates of complications and excellent cosmesis

Intraoperative Radiation Therapy as a Safe Alternative to Whole Breast Radiation for Treatment of Minimally Invasive Breast Cancers: A Retrospective Cohort Study

BACKGROUND

Intraoperative radiation therapy (IORT) in select populations is a viable alternative to whole breast radiation therapy (WBRT) in the treatment of biopsy-proven localized invasive and non-invasive breast cancer. We aim to assess recurrence and complication rates following IORT in lumpectomy patients at a community hospital in Baltimore City.

METHODS

An IRB-approved retrospective cohort study was conducted on consecutive cases of lumpectomy with IORT from 2013 through 2020 by a single surgeon. Patient demographics, tumor and operative characteristics, and complications were retrieved from electronic medical records. Primary outcomes were postoperative complications and local recurrence rates.

RESULTS

The final cohort included 117 patients with mean follow-up time of 2.60 + 1.78 years. Mean age was 69.84 + 8.77 years. Thirty-three (28.21%) of patients developed a seroma. Odds of seroma formation were mildly significant for skin spacing [OR: 1.18, 95% CI: (1.02-1.37)] and balloon fill volume [1.04 (1.00-1.08)], but not for age, BMI, diabetes, former or current smoking status, history of WBRT, tumor size, or balloon size. Three (2.6%) patients had local recurrence. Odds of local recurrence were mildly significant for increased tumor size [1.14 (1.04-1.24)] and not significant for any other covariates.

CONCLUSIONS

IORT exposure did not confer higher rates of complications and the local recurrence rate mirrored that of the general population undergoing lumpectomy and WBRT. This study demonstrates the need for equitable treatment options based on individual needs: IORT is a safe alternative to WBRT in certain subpopulations, especially those with physical, social, or personal limitations preventing participation in a 3- to 7-week time commitment of WBRT.

Recent Advances in Optimizing Radiation Therapy Decisions in Early Invasive Breast Cancer

Adjuvant whole breast irradiation after breast-conserving surgery is a well-established treatment standard for early invasive breast cancer. Screening, early diagnosis, refinement in surgical techniques, the knowledge of new and specific molecular prognostic factors, and now the standard use of more effective neo/adjuvant systemic therapies have proven instrumental in reducing the rates of locoregional relapses. This underscores the need for reliably identifying women with such low-risk disease burdens in whom elimination of radiation from the treatment plan would not compromise oncological safety. This review summarizes the current evidence for radiation de-intensification strategies and details ongoing prospective clinical trials investigating the omission of adjuvant whole breast irradiation in molecularly defined low-risk breast cancers and related evidence supporting the potential for radiation de-escalation in HER2+ and triple-negative clinical subtypes. Furthermore, we discuss the current evidence for the de-escalation of regional nodal irradiation after neoadjuvant chemotherapy. Finally, we also detail the current knowledge of the clinical value of stromal tumor-infiltrating lymphocytes and liquid-based biomarkers as prognostic factors for locoregional relapse.

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.

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.

Advances in Breast Cancer Radiotherapy: Implications for Current and Future Practice

Radiation therapy (RT) is an essential component in the management of breast cancer. Following breast-conserving surgery (BCS), adjuvant RT is the standard of care for most patients. Traditionally, RT was delivered with standard whole breast irradiation (WBI) over 5-7 weeks following BCS. However, WBI regimens have evolved; hypofractionated WBI now represents the standard approach, reducing the duration of treatment to 3-4 weeks. Over the past year, five-fraction WBI regimens have also emerged as standard of care for some patients based on data from the FAST and FAST-Forward trials. An alternative to WBI that is also available for patients with early-stage breast cancer following BCS is partial breast irradiation, which can reduce the duration of treatment and the volume of breast tissue irradiated. Outcomes from multiple randomized trials with over a 10-year follow-up have demonstrated the safety and efficacy of partial breast irradiation approaches. Single-fraction intraoperative RT has also been evaluated in two prospective trials although the outcomes available, as well as current guidelines, do not support its utilization outside of prospective studies. For patients requiring RT to the regional lymph nodes, data have demonstrated the safety of hypofractionated approaches for those undergoing BCS or mastectomy without reconstruction. Future directions for early-stage breast cancer radiotherapy include the study of even shorter regimens and studies evaluating the omission of RT versus omission of endocrine therapy for favorable-risk patients. Furthermore, studies are also underway evaluating shorter courses of radiation in patients undergoing breast reconstruction and the use of tumor genomics to identify appropriate patients for omission of radiation with limited nodal involvement.

Microbiome in human cancers

A microbiome is defined as the aggregate of all microbiota that reside in human digestive system and other tissues. This microbiota includes viruses, bacteria, fungi that live in various human organs and tissues like stomach, guts, oesophagus, mouth cavity, urinary tract, vagina, lungs, and skin. Almost 20 % of malignant cancers worldwide are related to microbial infections including bacteria, parasites, and viruses. The human body is constantly being attacked by microbes during its lifetime and microbial pathogens that have tumorigenic effects in 15-20 % of reported cancer cases. Recent scientific advances and the discovery of the effect of microbes on cancer as a pathogen or as a drug have significantly contributed to our understanding of the complex relationship between microbiome and cancer. The aim of this study is to overview some microbiomes that reside in the human body and their roles in cancer.

Ultra-Short Fraction Schedules as Part of De-intensification Strategies for Early-Stage Breast Cancer

Adjuvant radiation therapy (RT) following breast-conserving surgery (BCS) represents a standard approach for most patients treated with breast-conserving therapy (BCT) for early-stage breast cancer. The first-generation of adjuvant RT schedules delivered daily treatment to the whole breast over 5-7 weeks. Although efficacious, this presented patients with a protracted course of treatment, reducing compliance and quality of life. While hypofractionated whole-breast irradiation (WBI) has become the standard, and part of the second-generation of RT regimens, it still requires 3-4 weeks. Concurrently, partial-breast irradiation (PBI) has also been explored as a technique to complete RT in a much shorter time period (1-3 weeks). There are now seven trials confirming the efficacy of this shorter treatment approach compared with standard WBI. In an effort to further reduce treatment duration, ultra-short WBI and PBI regimens have recently emerged as the third-generation of breast radiation schedules, allowing for the completion of treatment in 5 days or less. With respect to WBI, recent data from the FAST-Forward trial (which evaluated five fractions of WBI delivered in 1 week) demonstrated no difference in clinical outcomes at 5 years, with limited difference in toxicity, compared with hypofractionated 3-week WBI. Regarding PBI, published data on five-fraction regimens delivered in 2 weeks have also demonstrated comparable outcomes at 10 years, with reduced toxicities with long-term follow-up. This report will review additional ongoing studies evaluating even shorter courses of adjuvant RT treatment (one to five fractions), including single-fraction PBI or WBI.

Modern Approaches for Breast Brachytherapy

Breast brachytherapy represents a radiation technique that can be utilized as both monotherapy and as a tumor bed boost following breast conserving surgery. As monotherapy, the rationale for brachytherapy is that the majority of residual disease and therefore recurrences occur in close proximity to the lumpectomy cavity; for boost treatment, brachytherapy represents a technique that provided a more conformal approach prior to 3D treatment planning, and more recently can be used in conjunction with oncoplastic surgery. Multiple guidelines are available to assist clinicians with patient selection for accelerated partial breast irradiation (APBI), and recent guidelines support brachytherapy as an appropriate technique to deliver APBI. Modern breast brachytherapy can be performed with interstitial or applicator-based brachytherapy with multilumen and strut devices offering the ability to provide greater skin, chest wall, and normal breast sparing than previous devices. Novel strategies are being evaluated, including high dose rate perioperative/intraoperative radiotherapy, permanent breast seed implants, and noninvasive breast brachytherapy. Additionally, studies are evaluating shorter courses of brachytherapy. Multiple Level I studies are now available supporting interstitial brachytherapy to deliver APBI while prospective data and the National Surgical Adjuvant Breast and Bowel Project B-39/Radiation Therapy Oncology Group 0413 trial are available with applicator brachytherapy and provide standardized prescriptions, target volume definitions, and dosimetric goals.

Accelerated partial breast irradiation-Redefining the treatment target for women with early stage breast cancer

Following breast conserving surgery, the standard of care has been to deliver adjuvant radiation therapy directed to the whole breast (WBI) over a period of 3-7 weeks. Over the past decade, increasing data have supported the concept that treatment to the whole breast may not be required in selected patients, allowing for the emergence of partial breast irradiation (PBI). Multiple randomized trials with 5-10 years of follow-up have been published documenting the safety and efficacy associated with PBI using multiple techniques. Questions that remain to be answered include (a) what is the optimal PBI technique for each clinical scenario, (b) are there additional patients that can be effectively managed with PBI approaches, and (c) are there different techniques/dose schedules that allow for further reduction in treatment duration and/or toxicities? Partial breast irradiation represents a standard approach for appropriately selected patients. PBI provides comparable clinical outcomes to WBI while allowing for a reduction in the duration treatment and the potential for reduced toxicities. Future studies may also help to better define which patients require no radiation, PBI, hypofractionated WBI or conventional WBI, based upon patient, clinical, pathologic features as well as potentially using tumor genetics.

Development and psychometric evaluation of a Dutch-translated shorter Breast Cancer Treatment Outcome Scale (Dutch BCTOS-13)

PURPOSE

To create a Dutch translated short version of the Breast Cancer Treatment Outcome Scale (BCTOS) and validate it in patients who have completed both breast conserving surgery and adjuvant radiotherapy.

METHODS

The BCTOS consists of items comparing the treated with the untreated breast. After forward and backward translation, we tested the BCTOS-12 plus 5 additional items. Two-hundred breast cancer patients treated with breast conserving therapy (BCT) between January 2016 and December 2017, were asked to complete the BCTOS items twice with a 2 week interval. The EORTC QLQ-BR23 breast and arm symptoms subscales were completed once in parallel. Feasibility was assessed by missing or non-unique answer rates and content validity with floor and ceiling effect analysis. Construct validity was evaluated with 1) principal component analysis (PCA) 2) convergent validity and 3) known groups comparison (clinical validity differentiating between patients with and without locoregional side effects). From all potential items with good feasibility, content and construct validity, items were selected for the Dutch BCTOS based on clinical validity. The relation to the EORTC QLQ-BR23 subscales and reliability was tested for the new Dutch BCTOS.

RESULTS

Hundred and one of 200 (50.5%) approached patients participated in this study, with follow-up after surgery ranging from 5 to 29 months. Feasibility was high (1.5% missing answers). Content validity testing showed a floor effect > 20% in all 17 items. PCA showed that all items loaded well (> 0.4) into the assigned subscale and revealed two distinct subscales: cosmesis and function. Based on clinical validity, item "breast shape" was replaced by "breast elevation/position" and "overall skin appearance". Very good clinical validity (Cohen's d = 1.38) was found for the new Dutch BCTOS-13. Correlation to the EORTC QLQ-BR23 subscales was high (ICC = 0.65-0.85) for both subscales. Test-retest reliability (Cohen's d = 0.105) and internal consistency (Cronbach's α =0.90) were excellent.

CONCLUSIONS

Psychometric evaluation of a newly developed Dutch BCTOS-13 questionnaire in BCT patients showed excellent results, that were slightly better than the original BCTOS-22 and the shortened BCTOS-12. The good clinical validity makes the BCTOS-13 a useful tool to identify patients with unfavourable cosmetic and functional outcomes, requiring specific attention.

Accelerated partial breast radiotherapy: a review of the literature and future directions

Breast conservation therapy exemplifies the tailoring of medicine in the care of patients with cancer. Akin to improvements in surgical approaches, accelerated partial breast irradiation (APBI) tailors the treatment volume and duration to the needs of well selected patients. Here, we examine the evidence supporting APBI as well as the lessons in patient selection, dose and delivery techniques. Examination of historical techniques and their associated outcomes will support more correct patient selection and treatment delivery in an era where we await the reports of several large prospective trials.

Long term radiographic findings of breast brachytherapy: Implications of surgical volume

PURPOSE

Little is known about long-term radiographic findings after treatment with accelerated partial breast irradiation (APBI).

METHODS

Univariate and multivariate analysis of factors leading to formation and resolution of seroma were performed in patients treated with lumpectomy and APBI.

RESULTS

Post-treatment images of 129 patients were reviewed by one radiologist. Median surgical excision volume was 108.9 cc (range 20.5-681.9). Primary mode of imaging was mammogram. Median time from end of RT to first and last surveillance image was 6 and 54 months, respectively. Median number of images was 7 (range 3-12). Seroma was identified in 98 (76%) patients, with median maximum diameter of 3.9 cm. Forty (41%) patients experienced resolution of seroma, at a median time of 29 months (range 6-74). On univariate analysis, surgical excision volume was associated with seroma formation, and tumor stage and margin re-excision were significant on univariate and multivariate analysis. No factors were associated with seroma resolution.

CONCLUSION

Seroma formation after APBI resolves around 2.5 years for many patients, but persists for others possibly due to primary tumor and surgical excision volumes. With revised criteria on the definition of positive margins, smaller volumes may lead to decreased risk of seroma formation for future patients.

Accelerated partial breast irradiation: a review and evaluation of indications for treatment

Accelerated partial breast irradiation (APBI) represents a well-studied treatment modality for the delivery of adjuvant radiation therapy following breast-conserving surgery. Interstitial APBI represents the APBI technique with the longest follow-up to date; data from randomized trials and matched pair analyses demonstrate equivalent local control to traditional whole-breast irradiation with comparable rates of toxicity and improved cosmesis. While less mature, prospective data support the efficacy and safety of applicator-based brachytherapy with new multilumen applicators offering the potential for improved outcomes. External beam APBI represents a noninvasive technique; however, concerns regarding toxicity with this technique have emerged though newer techniques may mitigate these concerns. Multiple guidelines have been published based on traditional clinical and pathologic criteria to help physicians offer APBI to appropriately selected patients.

Dosimetric Comparison Between 3-Dimensional Conformal and Robotic SBRT Treatment Plans for Accelerated Partial Breast Radiotherapy

Accelerated partial breast irradiation is an attractive alternative to conventional whole breast radiotherapy for selected patients. Recently, CyberKnife has emerged as a possible alternative to conventional techniques for accelerated partial breast irradiation. In this retrospective study, we present a dosimetric comparison between 3-dimensional conformal radiotherapy plans and CyberKnife plans using circular (Iris) and multi-leaf collimators. Nine patients who had undergone breast-conserving surgery followed by whole breast radiation were included in this retrospective study. The CyberKnife planning target volume (PTV) was defined as the lumpectomy cavity + 10 mm + 2 mm with prescription dose of 30 Gy in 5 fractions. Two sets of 3-dimensional conformal radiotherapy plans were created, one used the same definitions as described for CyberKnife and the second used the RTOG-0413 definition of the PTV: lumpectomy cavity + 15 mm + 10 mm with prescription dose of 38.5 Gy in 10 fractions. Using both PTV definitions allowed us to compare the dose delivery capabilities of each technology and to evaluate the advantage of CyberKnife tracking. For the dosimetric comparison using the same PTV margins, CyberKnife and 3-dimensional plans resulted in similar tumor coverage and dose to critical structures, with the exception of the lung V5%, which was significantly smaller for 3-dimensional conformal radiotherapy, 6.2% when compared to 39.4% for CyberKnife-Iris and 17.9% for CyberKnife-multi-leaf collimator. When the inability of 3-dimensional conformal radiotherapy to track motion is considered, the result increased to 25.6%. Both CyberKnife-Iris and CyberKnife-multi-leaf collimator plans demonstrated significantly lower average ipsilateral breast V50% (25.5% and 24.2%, respectively) than 3-dimensional conformal radiotherapy (56.2%). The CyberKnife plans were more conformal but less homogeneous than the 3-dimensional conformal radiotherapy plans. Approximately 50% shorter treatment times and 50% lower number of delivered monitor units (MU) were achievable with CyberKnife-multi-leaf collimator than with CyberKnife-Iris. The CyberKnife-multi-leaf collimator treatment times were comparable to 3-dimensional conformal radiotherapy, however, the number of MU delivered was approximately 2.5 times larger. The suitability of 10 + 2 mm margins warrants further investigation.

Accelerated partial breast irradiation

Local therapies to treat newly diagnosed breast cancer include a lumpectomy with radiation therapy or a mastectomy. The 20-year data from studies about the safety and efficacy of lumpectomy with full-breast radiation therapy support the safety of this regimen and its role to decrease the risk of ipsilateral recurrence and increase long-term survivorship of women with breast cancer. Accelerated partial breast irradiation (APBI) provides radiation therapy to the tumor bed but spares the remaining breast tissue. APBI accelerates the time required to complete the therapy regimen, with a range of one intraoperative session to five consecutive days compared to five to seven weeks. Several techniques exist to administer APBI, including the insertion of a balloon into the lumpectomy space. Of interest is the widespread use of APBI in community and academic settings that has preceded outcomes of large, randomized clinical trials. Because of selection bias in a number of small, single-institution, nonrandomized studies, published data are of limited value to ensure APBI as a standard of care.

[State of the art and perspectives of accelerated partial breast irradiation in 2014]

In the frame of treatment de-escalation and personalization, accelerated partial breast irradiation is taking its place in the breast cancer therapeutic options. This study analyzed the results of phase III randomized trials having compared accelerated partial breast irradiation versus whole breast irradiation. Currently, among those trails, six proposed some results regarding efficacy and/or toxicity. Globally, the non-randomized studies confirmed the expected results showing a low rate of local recurrence and toxicity. The first results of the phase III randomized trials showed encouraging data in terms of local control while the toxicity varied mainly according to the accelerated partial breast irradiation technique used. However, the follow-up of the majority of these studies remains insufficient. The strict respect of accelerated partial breast irradiation indications likely represents one of the key factors of the therapeutic success. The next results could allow proposing a better definition of the accelerated partial breast irradiation selection criteria.

Progress and controversies: radiation therapy for invasive breast cancer

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

Patient preferences regarding intraoperative versus external beam radiotherapy following breast-conserving surgery

The TARGIT-A Trial is an international randomized, prospective trial comparing intraoperative radiotherapy (IORT) for equivalence to external beam radiotherapy (EBRT) following lumpectomy for invasive breast cancer in selected low-risk patients; early results suggest that outcomes are similar. In addition to effectiveness data and cost considerations, the preferences of patients should help inform practice. This study was undertaken to explore and quantify preference in choosing between IORT and the current standard, EBRT. Eligible subjects were current or past candidates for breast-conserving surgery and radiation being seen at the University of California, San Francisco Breast Care Center. A trade-off technique varying the risk of local recurrence for IORT was used to quantify any additional accepted risk that these patients would accept to receive either treatment. Patients were first presented with a slideshow comparing EBRT with the experimental IORT option before being asked their preferences given hypothetical 10-year local recurrence risks. Patients were then given a questionnaire on demographic, social and clinical factors. Data from 81 patients were analyzed. The median additional accepted risk to have IORT was 2.3 % (-9 to 39 %), mean 3.2 %. Only 7 patients chose to accept additional risk for EBRT; 22 accepted IORT at no additional risk; and the remaining 52 chose IORT with some additional risk. Patients weigh trade-offs of risks and benefits when presented with medical treatment choices. Our results show that the majority of breast cancer patients will accept a small increment of local risk for a simpler delivery of radiation. Further studies that incorporate outcome and side effect data from the TARGIT-A trial clarify the expected consequences of a local recurrence, and include an expanded range of radiation options that could help guide clinical decision making in this area.