Are We Missing Acute Toxicities Associated With Hypofractionated Breast Irradiation? A Report From a Large Multicenter Cohort Study.

PURPOSE: The efficacy and long-term safety of hypofractionated whole breast irradiation (HF-WBI) have been established through multiple randomized trials, yet data about acute toxicities remain more limited. Since 2013, our group has prospectively collected acute toxicity data from weekly treatment evaluations and additional assessment after completion. In 2016, we intentionally shifted the posttreatment assessment follow-up visit from 1 month to 2 weeks to evaluate for missed acute toxicity occurring in that immediate posttreatment window. Here, we report whether 2-week follow-up has resulted in increased detection of acute toxicities compared with 4-week follow-up. METHODS AND MATERIALS: We prospectively compared acute toxicity for patients treated with HF-WBI between January 1, 2013, and August 31, 2015 (4 week follow-up cohort) to patients treated between January 1, 2016, and August 31, 2018 (2 week follow-up cohort). Analyses included a multivariable model that adjusted for other factors known to correlate with toxicity. We prospectively defined acute toxicity as maximum breast pain (moderate or severe rating) and/or occurrence of moist desquamation reported 7 days before the completion of radiation therapy (RT) until 42 days after completion. RESULTS: A total of 2689 patients who received postlumpectomy radiation and boost were analyzed; 1862 patients in the 2-week follow-up cohort and 827 in the 4-week follow-up cohort. All acute toxicity measures assessed were statistically similar between follow-up cohorts when compared in an unadjusted fashion. Overall acute composite toxicity was 26.4% and 27.7% for patients in the 4-week follow-up and 2-week follow-up cohorts, respectively. Overall acute composite toxicity remained similar between follow-up cohorts in a multivariable, adjusted model and was significantly related to patient's age, body mass index, smoking status, and treatment technique (intensity-modulated RT vs 3-dimensional conformal radiation therapy) but not follow-up cohort. CONCLUSIONS: An earlier posttreatment follow-up for HF-WBI patients did not reveal a significant increased incidence of acute toxicities at 2 weeks compared with 4 weeks. This study provides physicians and patients with additional data on the safety and tolerability of HF-WBI for early stage breast cancer.

Factors Associated With Cardiac Radiation Dose Reduction After Hypofractionated Radiation Therapy for Localized, Left-Sided Breast Cancer in a Large Statewide Quality Consortium.

PURPOSE: Limiting cardiac radiation dose is important for minimizing long-term cardiac toxicity in patients with left-sided early-stage breast cancer. METHODS AND MATERIALS: Prospectively collected dosimetric data were analyzed for patients undergoing moderately hypofractionated radiation therapy to the left breast within the Michigan Radiation Oncology Quality Consortium from 2016 to 2022. The mean heart dose (MHD) goal was progressively tightened from ≤2 Gy in 2016 to MHD ≤ 1.2 Gy in 2018. In 2021, a planning target volume (PTV) coverage goal was added, and the goal MHD was reduced to ≤1 Gy. Multivariate logistic regression models were developed to assess for covariates associated with meeting the MHD goals in 2016 to 2020 and the combined MHD/PTV coverage goal in 2021 to 2022. RESULTS: In total, 4165 patients were analyzed with a median age of 64 years. Overall average cardiac metric compliance was 91.7%. Utilization of motion management increased from 41.8% in 2016 to 2020 to 46.5% in 2021 to 2022. Similarly, use of prone positioning increased from 12.2% to 22.2% in these periods. On multivariate analysis in the 2016 to 2020 cohort, treatment with motion management (odds ratio [OR], 5.20; 95% CI, 3.59-7.54; P < .0001) or prone positioning (OR, 3.21; 95% CI, 1.85-5.57; P < .0001) was associated with meeting the MHD goal, while receipt of boost (OR, 0.25; 95% CI, 0.17-0.39; P < .0001) and omission of hormone therapy (OR, 0.65; 95% CI, 0.49-0.88; P = .0047) were associated with not meeting the MHD goal. From 2021 to 2022, treatment with motion management (OR, 1.89; 95% CI, 1.12-3.21; P = .018) or prone positioning (OR, 3.71; 95% CI, 1.73-7.95; P = .0008) was associated with meeting the combined MHD/PTV goal, while larger breast volume (≥1440 cc; OR, 0.34; 95% CI, 0.13-0.91; P = .031) was associated with not meeting the combined goal. CONCLUSIONS: In our statewide consortium, high rates of compliance with aggressive targets for limiting cardiac dose were achievable without sacrificing target coverage.

Large institutional experience of early outcomes and dosimetric findings with postoperative stereotactic partial breast irradiation in breast cancer.

PURPOSE: To analyze the dosimetric and toxicity outcomes of patients treated with postoperative stereotactic partial breast irradiation (S-PBI). METHODS: We identified 799 women who underwent S-PBI at our institution between January 2016 and December 2022. The most commonly used dose-fraction and technique were 30 Gy in 5 fractions (91.7 %) and a robotic stereotactic radiation system with real-time tracking (83.7 %). The primary endpoints were dosimetric parameters and radiation-related toxicities. For comparison, a control group undergoing ultra-hypofractionated whole breast irradiation (UF-WBI, n = 468) at the same institution was selected. RESULTS: A total of 815 breasts from 799 patients, with a median planning target volume (PTV) volume of 89.6 cm3, were treated with S-PBI. Treatment plans showed that the mean and maximum doses received by the PTV were 96.2 % and 104.8 % of the prescription dose, respectively. The volume of the ipsilateral breast that received 50 % of the prescription dose was 32.3 ± 8.9 %. The mean doses for the ipsilateral lung and heart were 2.5 ± 0.9 Gy and 0.65 ± 0.39 Gy, respectively. Acute toxicity occurred in 175 patients (21.5 %), predominantly of grade 1. Overall rate of late toxicity was 4 % with a median follow-up of 31.6 months. Compared to the UF-WBI group, the S-PBI group had comparably low acute toxicity (21.5 % vs. 25.2 %, p = 0.12) but significantly lower dosimetric parameters for all organs-at-risks (all p < 0.05). CONCLUSION: In this large cohort, S-PBI demonstrated favorable dosimetric and toxicity profiles. Considering the reduced radiation exposure to surrounding tissues, external beam PBI with advanced techniques should at least be considered over traditional WBI-based approaches for PBI candidates.

Axillary Treatment and Chronic Breast Cancer-Related Lymphedema: Implications for Prospective Surveillance and Intervention From a Randomized Controlled Trial.

PURPOSE: The PREVENT randomized trial assessed progression to chronic breast cancer-related lymphedema (cBCRL) after intervention triggered by bioimpedance spectroscopy (BIS) or tape measurement (TM). This secondary analysis identifies cBCRL risk factors on the basis of axillary treatment. METHODS: Between June 2014 and September 2018, 881 patients received sentinel node biopsy (SNB; n = 651), SNB + regional node irradiation (RNI; n = 58), axillary lymph node dissection (ALND; n = 85), or ALND + RNI (n = 87). The primary outcome was the 3-year cBCRL rate requiring complex decongestive physiotherapy (CDP). RESULTS: After a median follow-up of 32.8 months (IQR, 21-34.3), 69 of 881 patients (7.8%) developed cBCRL. For TM, 43 of 438 (9.8%) developed cBCRL versus 26 of 443 (5.9%) for BIS (P = .028). The 3-year actuarial risk of cBCRL was 4.4% (95% CI, 2.7 to 6.1), 4.2% (95% CI, 0 to 9.8), 25.8% (95% CI, 15.8 to 35.8), and 26% (95% CI, 15.3 to 36.7). Rural residence increased the risk in all groups. For SNB, neither RNI (SNB, 4.1% v SNB + RNI, 3.4%) nor taxane (4.4%) increased cBCRL, but risk was higher for patients with a BMI of ≥30 (6.3%). For SNB + RNI, taxane use (5.7%) or supraclavicular fossa (SCF) radiation (5.0%) increased cBCRL. For ALND patients, BMI ≥25 or chemotherapy increased cBCRL. For ALND + RNI, most patients received SCF radiation and taxanes, so no additional risk factors emerged. CONCLUSION: The extent of axillary treatment is a significant risk factor for cBCRL. Increasing BMI, rurality, SCF radiation, and taxane chemotherapy also increase risk. These results have implications for a proposed risk-based lymphedema screening, early intervention, and treatment program.

Outcome of different radiotherapy strategies after breast conserving surgery in patients with ductal carcinoma in situ (DCIS).

BACKGROUND: Adjuvant radiotherapy (RT) after breast-conserving surgery for DCIS lowers the relative local recurrence risk by half. To identify a low-risk group with the minimal benefit of RT could avoid side effects and spare costs. In this study, the outcome was compared for different RT-strategies using data from the randomized SweDCIS trial. MATERIAL AND METHODS: Five strategies were compared in a Swedish setting: RT-to-none or all, RT to high-risk women defined by DCISionRT, modified Radiation Therapy Oncology Group (RTOG) 9804 criteria, and Swedish Guidelines. Ten-year recurrence risks and cost including adjuvant RT and local recurrence treatment cost were calculated. RESULTS: The mean age at recurrence was 64.4 years (36-90) and the mean cost for treating a recurrence was $21,104. In the SweDCIS cohort (n = 504), 59 women developed DCIS, and 31 invasive recurrence. Ten-year absolute local recurrence risk (invasive and DCIS) according to different strategies varied between 18.6% (12.5-23.6%) and 7.8% (5.0-12.6%) for RT-to-none or to-all, with an additional cost of $2614 US dollars per women and $24,201 per prevented recurrence for RT-to-all. The risk differences between other strategies were not statistically significant, but the larger proportion receiving RT, the fewer recurrences. DCISionRT spared 48% from RT with 8.1% less recurrences compared to RT-to-none, and a cost of $10,534 per prevented recurrence with additional cost depending on the price of the test. RTOG 9804 spared 39% from RT, with 9.7% less recurrences, $9525 per prevented recurrence and Swedish Guidelines spared 13% from RT, with 10.0% less recurrences, and $21,521 per prevented recurrence. CONCLUSION: It seems reasonable to omit RT in pre-specified low-risk groups with minimal effect on recurrence risk. Costs per prevented recurrence varied more than two-fold but which strategy that could be considered most cost-effective needs to be further evaluated, including the DCISionRT-test price.

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

PURPOSE: Shorter courses of breast radiotherapy are offered as an alternative to 4 weeks of whole-breast irradiation after lumpectomy, including brachytherapy. A prospective phase 2multi-institution clinical trial to study 3-fraction accelerated partial breast irradiation delivered by brachytherapy was conducted. METHODS AND MATERIALS: The trial treated selected breast cancers after breast-conserving surgery with brachytherapy applicators that delivered 22.5 Gy in 3 fractions of 7.5 Gy. The planning treatment volume was 1 to 2 cm beyond the surgical cavity. Eligible women were age ≥45 years with unicentric invasive or in situ tumors ≤3 cm excised with negative margins and with positive estrogen or progesterone receptors and no metastases to axillary nodes. Strict dosimetric parameters were required to be met and follow up information was collected from the participating sites. RESULTS: Two hundred patients were prospectively enrolled; however, a total of 185 patients who were enrolled were followed for a median of 3.63 years. Three-fraction brachytherapy was associated with low chronic toxicity. There was excellent or good cosmesis in 94% of patients. There were no grade 4 toxicities. Grade 3 fibrosis at the treatment site was present in 1.7% and 32% percent had grades 1 or 2 fibrosis at the treatment site. There was 1 rib fracture. Other late toxicities included 7.4% grade 1 hyperpigmentation, 2% grade 1 telangiectasias, 1.7% symptomatic seromas, 1.7% abscessed cavities, and 1.1% symptomatic fat necrosis. There were 2 (1.1%) ipsilateral local recurrences, 2 (1.1%) nodal recurrences and no distant recurrences. Other incidents included one contralateral breast cancer and 2 second malignancies (lung). CONCLUSIONS: Ultra-short breast brachytherapy is feasible and has excellent toxicity and could be an alternative to standard 5-day, 10 fraction accelerated partial breast irradiation in eligible patients. Patients from this prospective trial will continue to be followed to evaluate long-term outcomes.

Breast brachytherapy: Building a bright future on the foundation of a rich history of advancement in technology, technique, and patient-centered care.

For over 20 years, the concept of accelerated partial breast irradiation (APBI) has received considerable attention. Initially concentrating on the appropriateness of APBI as an alternative treatment to whole breast radiotherapy, investigation and innovation evolved towards dose delivery and technique appropriateness. The purpose of this article is to review the pertinent literature that supports the role brachytherapy serves in delivering APBI and the recognized brachytherapy techniques for dose delivery. Publications establishing techniques utilizing multicatheter brachytherapy, single-entry brachytherapy applicators, permanent breast seed implantation brachytherapy, noninvasive breast brachytherapy and electronic brachytherapy are described. The use of brachytherapy for repeat breast conservation therapy is additionally reviewed. A historical perspective and potential direction of future investigation and innovation are presented.

Current Diagnostic Tools for Breast Cancer-Related Lymphedema.

PURPOSE OF REVIEW: Breast cancer-related lymphedema (BCRL) can have a significant impact on breast cancer survivors quality of life. The purpose of this review is to evaluate diagnostic tools for the assessment of BCRL. RECENT FINDINGS: Multiple BCRL diagnostic tools are available, though older diagnostic tools have low sensitivity, limiting the ability for sub-clinical BCRL diagnosis while BIS and perometry have increased sensitivity and the ability to diagnose BCRL sub-clinically. Prospective studies have demonstrated such an approach coupled to early intervention is associated with low rates of chronic BCRL while a recently published randomized trial demonstrated that prospective surveillance with BIS coupled with early intervention reduced rates of chronic BCRL as compared to circumference measurements with compression garments. Prospective and randomized data support the use of prospective surveillance for BCRL. The strongest data available comes from the PREVENT trial and supports prospective BCRL surveillance with bioimpedance spectroscopy coupled to early intervention with a compression sleeve.

Bioimpedance spectroscopy for breast cancer-related lymphedema assessment: clinical practice guidelines.

PURPOSE: Breast cancer-related lymphedema (BCRL) represents a significant concern for patients following breast cancer treatment, and assessment for BCRL represents a key component of survivorship efforts. Growing data has demonstrated the benefits of early detection and treatment of BCRL. Traditional diagnostic modalities are less able to detect reversible subclinical BCRL while newer techniques such as bioimpedance spectroscopy (BIS) have shown the ability to detect subclinical BCRL, allowing for early intervention and low rates of chronic BCRL with level I evidence. We present updated clinical practice guidelines for BIS utilization to assess for BCRL. METHODS AND RESULTS: Review of the literature identified a randomized controlled trial and other published data which form the basis for the recommendations made. The final results of the PREVENT trial, with 3-year follow-up, demonstrated an absolute reduction of 11.3% and relative reduction of 59% in chronic BCRL (through utilization of compression garment therapy) with BIS as compared to tape measurement. This is in keeping with real-world data demonstrating the effectiveness of BIS in a prospective surveillance model. For optimal outcomes patients should receive an initial pre-treatment measurement and subsequently be followed at a minimum quarterly for first 3 years then biannually for years 4-5, then annually as appropriate, consistent with previous guidelines; the target for intervention has been changed from a change in L-Dex of 10 to 6.5. The lack of pre-operative measure does not preclude inclusion in the prospective surveillance model of care. CONCLUSION: The updated clinical practice guidelines present a standardized approach for a prospective model of care using BIS for BCRL assessment and supported by evidence from a randomized controlled trial as well as real-world data.

Cost-Effectiveness Analysis of Ultra-Hypofractionated Whole Breast Radiation Therapy Alone Versus Hormone Therapy Alone or Combined Treatment for Low-Risk ER-Positive Early Stage Breast Cancer in Women Aged 65 Years and Older.

PURPOSE: The optimal management of early-stage, low-risk, hormone-positive breast cancer in older women remains controversial. Recent trials have shown that 5-fraction ultrahypofractionated whole-breast irradiation (U-WBI) has similar outcomes to longer courses, reducing the cost and inconvenience of treatment. We performed a cost-utility analysis to compare U-WBI to hormone therapy alone or their combination. METHODS AND MATERIALS: We simulated 3 different treatment approaches for women age 65 years or older with pT1-2N0 ER-positive invasive ductal carcinoma treated with lumpectomy with negative margins using a Markov microsimulation model. The strategies were U-WBI performed with a 3-dimensional conformal technique over 5 fractions without a boost ("radiation therapy [RT] alone"), adjuvant hormone therapy (anastrozole for 5 years) without RT ("aromatase-inhibitor [AI] alone"), or the combination of the 2. The combination strategy was calibrated to match trial results, and the relative effectiveness of the RT alone and AI alone strategies were inferred from previous randomized trials. The primary endpoint was the cost-effectiveness of the 3 strategies over a lifetime horizon as measured by the incremental cost-effectiveness ratio (ICER), with a value of $100,000/quality-adjusted life-year deemed "cost-effective." RESULTS: The model results compared with the prespecified target outcomes. On average, RT alone was the least expensive strategy ($14,775), with AI alone slightly more ($14,998), and combination therapy the costliest ($19,802). RT alone dominated AI alone (the incremental cost-effectiveness ratio [ICER] -$5089). Combination therapy, compared with RT alone, was slightly more expensive than our definition of cost-effective (ICER $113,468) but was cost-effective compared with AI alone (ICER $54,451). Probabilistic sensitivity analysis demonstrated RT alone to be cost-effective in 50% of trials, with combination therapy in 36% and AI alone in 14%. CONCLUSIONS: U-WBI alone appears the more cost-effective de-escalation strategy for these low-risk patients, compared with AI alone. Combining U-WBI and AI appears more costly but may be preferred by some patients.

Stereotactic Partial Breast Irradiation: What Does the Future Hold?

Breast irradiation has evolved significantly over the last several decades. Accelerated partial breast and stereotactic breast irradiation have evolved as strategies to reduce irradiated volumes, preserve appropriate oncologic control, and improve cosmetic outcome. The sequencing and/or combination of stereotactic partial breast irradiation with novel systemic agents is of great interest to the oncologic community. Here we explore the landscape of modern trials and opine on the future of partial breast irradiation.

An Estimate of Local Failure in the TARGIT-A Trial of Pre-pathology Intraoperative Radiation Therapy for Early Breast Cancer.

PURPOSE: TARGIT-A was a pragmatic randomized noninferiority trial including women with early-stage breast cancer treated postlumpectomy with either external beam radiation therapy (EBRT) or 50 kV x-rays delivered intraoperatively with or without EBRT, as indicated. The long-term update of the pre-pathology cohort did not include a 10-year estimate of the primary endpoint of local failure (although tabular 5-year data was provided). Here, we used the data from the pre-pathology manuscript to estimate the cumulative incidence of local failure. METHODS AND MATERIALS: Using digitizer software and the published survival curves, we extracted the Kaplan-Meier rate of local recurrence-free survival and overall survival. The extracted data were calibrated to the published point-estimates to within ±0.5%. The data were then fit to parametric survival models, and overall survival and local recurrence-free survival curves were subtracted to give the estimate of local failure in the presence of the competing risk of death. Bootstrap resampling was used to assess for parameter uncertainty in the modeling process. RESULTS: Our analysis estimated that the risk of local failure at 10 years in the TARGIT-A pre-pathology cohort is approximately 1.7% with EBRT (95% confidence interval [CI], 0%-4.3%) and 5.5% in the pragmatic risk-adapted TARGIT strategy (95% CI, 2.9%-8.0%). A weighted average estimate suggests that the risk of local failure in low-risk women treated with TARGIT alone is approximately 6.6% at 10 years (95% CI, 3.3%-10.0%), with an estimated difference of 4.9% (95% CI, 0.6%-9.2%) compared with EBRT. CONCLUSIONS: These data allow for contextualization and informed decisions when considering megavoltage EBRT, kilovoltage intraoperatively, or omission of radiation therapy entirely.

A Novel Biosignature Identifies Patients With DCIS With High Risk of Local Recurrence After Breast Conserving Surgery and Radiation Therapy.

PURPOSE: There is an unmet need to identify women diagnosed with ductal carcinoma in situ (DCIS) with a low risk of in-breast recurrence (IBR) after breast conserving surgery (BCS), which could omit radiation therapy (RT), and also to identify those with elevated IBR risk remaining after BCS plus RT. We evaluated a novel biosignature for a residual risk subtype (RRt) to help identify patients with elevated IBR risk after BCS plus RT. METHODS AND MATERIALS: Women with DCIS treated with BCS with or without RT at centers in the US, Australia, and Sweden (n = 926) were evaluated. Patients were classified into 3 biosignature risk groups using the decision score (DS) and the RRt category: (1) Low Risk (DS ≤2.8 without RRt), (2) Elevated Risk (DS >2.8 without RRt), and (3) Residual Risk (DS >2.8 with RRt). Total and invasive IBR rates were assessed by risk group and treatment. RESULTS: In patients at low risk, there was no significant difference in IBR rates with or without RT (total, P = .8; invasive IBR, P = .7), and there were low overall 10-year rates (total, 5.1%; invasive, 2.7%). In patients with elevated risk, IBR rates were decreased with RT (total: hazard ratio [HR], 0.25; P < .001; invasive: HR, 0.28; P = .005); 10-year rates were 20.6% versus 4.9% (total) and 10.9% versus 3.1% (invasive). In patients with residual risk, although IBR rates decreased with RT after BCS (total: HR, 0.21; P < .001; invasive: HR, 0.29; P = .028), IBR rates remained significantly higher after RT compared with patients with elevated risk (HR, 2.5; 95% CI, 1.2-5.4; P = .018), with 10-year rates of 42.1% versus 14.7% (total) and 18.3% versus 6.5% (invasive). CONCLUSIONS: The novel biosignature identified patients with 3 distinct risk profiles: Low Risk patients with a low recurrence risk with or without adjuvant RT, Elevated Risk patients with excellent outcomes after BCS plus RT, and Residual Risk patients with an elevated recurrence risk remaining after BCS plus RT, warranting potential intensified or alternative treatment approaches.

A fully automatic framework for evaluating cosmetic results of breast conserving therapy.

The breast cosmetic outcome after breast conserving therapy is essential for evaluating breast treatment and determining patient's remedy selection. This prompts the need of objective and efficient methods for breast cosmesis evaluations. However, current evaluation methods rely on ratings from a small group of physicians or semi-automated pipelines, making the processes time-consuming and their results inconsistent. To solve the problem, in this study, we proposed: 1. a fully-automatic Machine Learning Breast Cosmetic evaluation algorithm leveraging the state-of-the-art Deep Learning algorithms for breast detection and contour annotation, 2. a novel set of Breast Cosmesis features, 3. a new Breast Cosmetic dataset consisting 3k+ images from three clinical trials with human annotations on both breast components and their cosmesis scores. We show our fully-automatic framework can achieve comparable performance to state-of-the-art without the need of human inputs, leading to a more objective, low-cost and scalable solution for breast cosmetic evaluation in breast cancer treatment.

Partial breast irradiation: An updated consensus statement from the American brachytherapy society.

PURPOSE: In recent years, results with mature follow-up have been reported for several Phase III trials randomizing women to receive whole breast irradiation (WBI) versus varying modalities of partial breast irradiation (PBI). It is important to recognize that these methods vary in terms of volume of breast tissue treated, dose per fraction, and duration of therapy. As such, clinical and technical guidelines may vary among the various PBI techniques. METHODS: Members of the American Brachytherapy Society with expertise in PBI performed an extensive literature review focusing on the highest quality data available for the numerous PBI options offered in the modern era. Data were evaluated for strength of evidence and published outcomes were assessed. RESULTS: The majority of women enrolled on randomized trials of WBI versus PBI have been age >45 years with tumor size <3 cm, negative margins, and negative lymph nodes. The panel also concluded that PBI can be offered to selected women with estrogen receptor negative and/or Her2 amplified breast cancer, as well as ductal carcinoma in situ, and should generally be avoided in women with extensive lymphovascular space invasion. CONCLUSIONS: This updated guideline summarizes published clinical trials of PBI methods. The panel also highlights the role of PBI for women facing special circumstances, such as history of cosmetic breast augmentation or prior breast irradiation, and discusses promising novel modalities that are currently under study, such as ultrashort and preoperative PBI. Updated consensus guidelines are also provided to inform patient selection for PBI and to characterize the strength of evidence to support varying PBI modalities.