Updates on the APBI-IMRT-Florence Trial (NCT02104895) Technique: From the Intensity Modulated Radiation Therapy Trial to the Volumetric Modulated Arc Therapy Clinical Practice

Comparison of Acute and Late Toxicities With Daily Versus Every-Other-Day 5-Fraction Partial Breast Radiation Therapy

PURPOSE

Partial breast irradiation (PBI) delivered with intensity modulated radiation therapy over 5 fractions every other day represents an attractive, convenient method of delivering adjuvant radiation therapy for well-selected patients without compromising oncologic or toxicity outcomes. Condensing this regimen to a week of treatment through consecutive daily delivery may further increase patient convenience, though a comparison of toxicities between daily and every other day regimens is limited.

METHODS AND MATERIALS

We retrospectively reviewed 507 patients from an institutional registry undergoing PBI for ductal carcinoma in situ (DCIS) or early-stage breast cancer (T1-2N0/x) from 2015 to 2022. All patients received 30 Gy in 5 fractions with intensity modulated radiation therapy. Acute (toxicity within 90 days of treatment) and chronic toxicity were recorded.

RESULTS

Of the 507 patients, 351 were treated every other day, and 159 were treated daily. Median follow-up was longer in the every-other-day group (2.4 vs 1.9 years, P < .001). With regards to acute toxicity, there was slightly reduced grade 1 to 2 dermatitis with daily treatment (39% every other day vs 35% daily, P = .06), while rates of fatigue (18% every other day vs 20% daily, P = .09) were similar. Rates of chronic toxicities were comparable between the two approaches, with no differences in the rates of chronic hyperpigmentation (14% every other day vs 14% daily, P = .97), telangiectasias (1% every other day vs 1% daily, P = .92), mild fibrosis/induration (13% every other day vs 13% daily, P = .91), and lymphedema (0% every other day vs 1% daily, P = .31).

CONCLUSIONS

Overall, 5-fraction PBI delivered daily appears to be well tolerated with similar acute and chronic toxicity to every other day fractionation.

Ultrahypofractionated partial breast irradiation following oncoplastic surgery: secondary analysis of a phase II trial

PURPOSE

Although partial breast irradiation (PBI) is accepted as an effective and cosmesis-preserving technique for low-risk early-stage breast cancer following standard lumpectomy, data supporting PBI following oncoplastic surgery are sparse. We report prospective data in efforts to determine whether PBI can be safely utilized after oncoplastic surgery.

METHODS

Patients with low-risk stage 0-1 breast cancer following successful lumpectomy with optional oncoplastic reconstruction were enrolled on a phase II trial. Patients were treated with a modified Florence regimen to 30 Gy in 5 fractions on the Varian Edge radiosurgery system using IMRT or VMAT. Presurgical MRI, post-operative seroma and surgical clips were used to assist target delineation. The effect of oncoplastic surgery on radiation dosimetry and Breast Cancer Treatment Outcome Scale scores were assessed using student's t-test for continuous variables and chi-square for categorical variables.

RESULTS

From 2018 to 2022, 50 patients with 52 tumors were enrolled with 48% undergoing oncoplastic reconstruction. Although median PTV volumes were numerically larger in the oncoplastic group (266 cc vs. 223 cc), there were no statistically significant differences in PTV volumes, ratio of PTV to whole breast or mean heart or lung doses (p > 0.05). Mean baseline BCTOS aesthetic scores were 1.35 for standard lumpectomy vs. 2.52 for oncoplastic (p = 0.003). At long-term follow-up > 2 years, mean BCTOS aesthetic scores were 1.29 for standard lumpectomy vs. 1.35 for oncoplastic (p = 0.71). At a median follow-up of 46 months, there were no local recurrences.

CONCLUSIONS

When utilizing pre-treatment MRI, surgical clips and a relatively large PTV, PBI after oncoplastic surgery was safe and effective for appropriately selected patients. In combination with oncoplastic surgery, partial breast irradiation achieves excellent long-term cosmesis that improves over time.

A robust planning approach for respiratory motion in accelerated partial breast irradiation using volumetric modulated arc therapy

Accelerated partial breast irradiation (APBI) is an alternative treatment for early-stage breast cancer. This study aimed to evaluate the effectiveness of the virtual bolus (VB) method and robust planning against respiratory motion in volumetric modulated arc therapy (VMAT)-APBI. VMAT plans were generated with 30 Gy in 5 fractions for 16 patients. Four treatment plans were developed and compared: a standard optimization (SO) plan without robust methods, a pseudo-skin flash strategy using a 5 mm VB (with densities of 0.4 and 1.0 g/cm3, VB04 and VB10), and a robust optimization (RO) plan to minimize penalties in worst-case scenarios. The isocenter was shifted 1-5 mm in each translational direction in robust analysis, and perturbed dose calculations were performed. All dose constraints for the target in SO and VB plans were within acceptable limits, but the dose evaluation volume V95% in the RO plan was lower than in other plans (P < 0.05). The clinical target volume V95% of the RO plan was significantly higher than in VB04 and VB10 (P < 0.05). The RO plan showed the best performance for organs at risk, followed by SO and VB plans, which resulted in higher doses. The RO plan exhibited the smallest change (±2%) in dose distribution due to respiratory motion. By contrast, the SO plan lacked robustness owing to absence of sufficient fluence in the air surrounding the planning target volume outside of the skin surface. The RO plan offers superior target coverage, maximum dose, and robustness compared to SO and VB methods.

Fat necrosis after accelerated partial breast irradiation or hypofractionated whole breast irradiation: A case-control study

PURPOSE

This study aimed to compare the incidence of fat necrosis after accelerated partial breast irradiation (APBI) vs hypofractionated whole breast irradiation (WBI) in patients with early-stage breast cancer.

MATERIALS AND METHODS

Data from early-stage breast cancer patients who underwent breast-conserving surgery and adjuvant radiotherapy between 2009 and 2022 were retrospectively collected. Radiation therapy consisted of APBI of 30 Gy in 5 daily fractions (Fx) (delivered in one week, consecutively) to the tumour bed or WBI (42.4 Gy in 16 Fx). Reports on fat necrosis were extracted from yearly mammograms and breast ultrasound imaging. The primary endpoint was the incidence of radiologically detected fat necrosis.

RESULTS

A total of 536 patients were included among the APBI and WBI cohorts, with 268 and 268 patients respectively. The three-year Kaplan-Meier actuarial rate of fat necrosis was 32.8% (95% CI: 30.0% - 35.6%) for APBI and 22.3% (95% CI: 19.7% - 24.9%) for WBI patients. Univariate Kaplan-Meier survival analysis revealed a Hazard Ratio of 1.6 [95% CI: 1.1 - 2.2; p = 0.0055] for the fat necrosis rate within the APBI group compared to WBI. Multivariate Cox proportional hazard regression confirmed significant associations between fat necrosis and APBI (HR = 2.2 95% CI: 1.2 - 4.0; p = 0.01).

CONCLUSIONS

The occurrence of radiologically diagnosed fat necrosis was higher in the APBI group compared to the WBI. Further investigations aiming to identify a lower-dose schedule with comparable efficacy to 30 Gy in 5 Fx but fewer toxicities, particularly for high-risk patients, are warranted.

Technical feasibility of delivering a simultaneous integrated boost in partial breast irradiation

Feasibility of volumetric modulated arc therapy (VMAT) for partial breast irradiation (PBI) with simultaneous integrated boost (SIB) to tumour bed was investigated. Four plans were created for 10 patients: 30 Gy/5 fractions, 26 Gy/5 fractions with 30 Gy SIB, 40.05 Gy/15 fractions, and 40.05 Gy/15 fractions with 48 Gy SIB. SIB in the 5 fraction arm had reduced ipsilateral breast dose relative to uniform dose. SIB in the 15 fraction arm had noninferior conformity compared to uniform dose. Addition of SIB did not increase other organ-at-risk doses or plan complexity. VMAT PBI with SIB was feasible for both fractionation regimens.

Comparative Analysis of Dosimetry: IMRT versus 3DCRT in Left-Sided Breast Cancer Patients with Considering Some Organs in Out - of - Field Borders

Purpose

The local management approach for node-positive breast cancer has undergone substantial evolution. Consequently, there exists a pressing need to enhance our treatment strategies by placing greater emphasis on planning and dosimetric factors, given the availability of more conformal techniques and delineation criteria, achieving optimal goals of radiotherapy treatment. The primary aim of this article is to discuss how the extent of regional nodal coverage influences the choice between IMRT and 3D radiation therapy for patients.

Patients and Methods

A total of 15 patients diagnosed with left breast cancer with disease involved lymph nodes were included in this study. Delivering the recommended dose required the use of a linear accelerator (LINAC) with photon beams energy of 6 mega voltage (6MV). Each patient had full breast radiation using two planning procedures: intensity-modulated radiotherapy (IMRT) and three-dimensional radiotherapy (3D conformal). Following the guidelines set forth by the Radiation Therapy Oncology Group (RTOG), the planned treatment coverage was carefully designed to fall between 95% and 107% of the recommended dose. Additionally, Dose Volume Histograms (DVHs) were generated the dose distribution within these anatomical contours.

Results and Conclusion

The DVH parameters were subjected to a comparative analysis, focusing on the doses absorbed by both Organs at Risk (OARs) and the Planning Target Volume (PTV). The findings suggest that low doses in IMRT plan might raise the risk of adverse oncological outcomes or potentially result in an increased incidence of subsequent malignancies. Consequently, the adoption of inverse IMRT remains limited, and the decision to opt for this therapy should be reserved for situations where it is genuinely necessary to uphold a satisfactory quality of life. Additionally, this approach helps in reducing the likelihood of developing thyroid problems and mitigates the risk of injuries to the supraclavicular area and the proximal head of the humerus bone.

Stereotactic body radiotherapy using CyberKnife versus interstitial brachytherapy in accelerated partial breast irradiation on left-sided breast: A comparison of dosimetric characteristics and preliminary clinical results

INTRODUCTION

We compared the dosimetric characteristics of the target and organs at risk (OARs) as well as the preliminary clinical outcomes between two accelerated partial breast irradiation (APBI) techniques.

METHODS

Forty-four patients diagnosed with left-sided early breast cancer who underwent APBI using either interstitial brachytherapy (IB) or stereotactic body radiation therapy (SBRT) with CyberKnife (CK) were retrospectively reviewed. The dosimetric parameters of the target and OARs were compared. Preliminary clinical outcomes, including tumor control and acute toxicity, were analyzed.

RESULTS

Treatment plans with CK demonstrated a better cardiac dose-sparing effect. Radiation doses to the heart at V150cGy for the CK and IB groups were 24.4 % and 60.4 %, respectively (p < 0.001), while the mean heart doses for the CK and IB groups were 107.4 cGy and 204 cGy, respectively (p < 0.001). The heart D1c.c. and the ipsilateral lung received a lower dose in the IB group, without any significant differences. The median follow-up time in the CK and IB groups was 28.6 and 61.3 months, respectively. No patients died from either breast cancer or cardiac events during follow-up. A locoregional recurrence event at the neck occurred in one patient within the IB group.

CONCLUSIONS

APBI planned by CK was shown to have a better dose-sparing effect on the heart, as well as better conformity and homogeneity to the target. CK is a non-invasive treatment which showed minimal acute toxicity and promising tumor control.

Master Breast Radiation Planning: Simple Guide for Radiation Oncology Residents

This article focuses on various aspects of breast radiation treatment planning, from simulation to field design. It covers the most common techniques including tangents, mono isocentric, dual isocentric, electron-photon match, and VMAT. This can serve as a guide for radiation oncology residents and medical students to advance their understanding of key aspects of breast radiation treatment and planning processes.

Organ-sparing techniques and dose-volume constrains used in breast cancer radiation therapy - Results from European and Latin American surveys

Background

Advances in local and systemic therapies have improved the outcomes of patients with breast cancer (BC), leading to a possible increased risk for postoperative radiation therapy (RT) late adverse events. The most adequate technologies and dose constraints for organs at risk (OAR) in BC RT have yet to be defined.

Methods

An online survey was distributed to radiation oncologists (ROs) practicing in Europe and Latin America including the Caribbean (LAC) through personal contacts, RO and BC professional groups' networks. Demographic data and clinical practice information were collected.

Results

 The study included 585 responses from ROs practicing in 57 different countries. The most frequently contoured OAR by European and LAC participants were the whole heart (96.6 % and 97.7 %), the ipsilateral (84.3 % and 90.8 %), and contralateral lung (71.3 % and 77.4 %), whole lung (69.8 % and 72.9 %), and the contralateral breast (66.4 % and. 83.2 %). ESTRO guidelines were preferred in Europe (33.3 %) and the RTOG contouring guideline was the most popular in LAC (62.2 %), while some participants used both recommendations (13.2 % and 19.2 %). IMRT (68.6 % and 59.1 %) and VMAT (65.6 % and 60.2 %) were the preferred modalities used in heart sparing strategies, followed by deep inspiration breath-hold (DIBH) (54.8 % and 37.4 %) and partial breast irradiation (PBI) (41.6 % and 24.6 %). Only a small percentage of all ROs reported the dose-volume constraints for OAR used in routine clinical practice. A mean heart dose (Heart-Dmean) between 4 and 5 Gy was the most frequently reported parameter (17.2 % and 39.3 %).

Conclusion

 The delineation approaches and sparing techniques for OAR in BC RT vary between ROs worldwide. The low response rate to the dose constraints subset of queries reflects the uncertainty surrounding this topic and supports the need for detailed consensus recommendations in the clinical practice.

Long-term results of intraoperative multicatheter breast implant (IOMBI) for accelerated partial breast irradiation (APBI) on early breast cancer patients

BACKGROUND AND PURPOSE

Multicatheter breast brachytherapy is a standard technique for accelerated partial breast irradiation (APBI) in early breast cancer patients. Intraoperative multicatheter breast implant (IOMBI) followed by perioperative high-dose-rate brachytherapy (PHDRBT) offers a novel and advantageous approach. We present long-term oncological, toxicity, and cosmesis outcomes for a well-experienced single institution.

MATERIALS AND METHODS

Eligible women aged ≥ 40 years with clinically and radiologically confirmed unifocal invasive or in situ ≤ 3 cm breast tumors underwent IOMBI during breast-conserving surgery. Patients meeting APBI criteria by definitive pathologic results received 3.4 Gy × 10fx with PHDRBT. Patients not suitable for APBI received PHDRBT-boost followed by WBRT.

RESULTS

A total of 171 patients underwent IOMBI during BCS, 120 patients (70.1 %) were suitable for APBI and 51 (29.8 %) for anticipated PHDRBT-boost. The median age was 61 years (range: 40-78), the median tumor size was 1.1 cm (range: 0.2-3.5), with a histological diagnosis of invasive ductal carcinoma in 78.9 % and ductal in situ in 21.1 %. A median of 9 catheters (range: 4-14) were used. For APBI, the median CTV and V100 were 40.8 cc (range: 8.6-99) and 35.4 cc (range: 7.2-94). The median of healthy breast tissue irradiated represents 7.2 % (range: 2.3-28 %) and the median local treatment duration was 10 days (range: 7-16). With a median follow-up of 8.8 years (range: 0.3-16.25), the 8-year local, locoregional, and distant control rates were 99 %, 98.1 %, and 100 %. G1-G2 late-toxicity rate was 53.4 %. Long-term cosmetic evaluation was excellent-good in 90.8 %.

CONCLUSION

IOMBI&PHDRBT program reports excellent long-term oncological outcomes, with a reduction from unnecessary irradiation exposure which translates into low long-term toxicity and good cosmesis outcomes, especially on well-selected APBI patients.

Effectiveness and toxicity of five-fraction prone accelerated partial breast irradiation

PURPOSE

Our institution was an early adopter of 5-fraction accelerated partial breast irradiation (ABPI) to treat women with early-stage breast cancer. This study reports long-term oncologic and cosmetic outcomes.

METHODS

We included patients receiving APBI 600 cGy × 5 fx delivered every other day or every day between 2010 and 2022. Logistic regression models were used to identify factors associated with development of late toxicities, clinician, and patient-rated cosmesis. Kaplan-Meier methodology was used to calculate overall survival (OS), disease-free survival (DFS), and locoregional recurrence-free survival (LR-RFS).

RESULTS

442 patients received APBI either daily (56%) or every other day (44%) in the prone position (92%). At a median follow-up of 48 months (range: 5.96-155 months), 12 (2.7%) patients developed a local recurrence (LR). Out of 258 patients with > 3-month toxicity data available, the most common late grade ≥ 2 adverse event was breast fibrosis (6.2%). On multivariate analysis, daily APBI treatment (vs every other day) did not correlate with an increased risk of any late grade ≥ 2 toxicity though it did correlate with a lower risk of any late grade ≥ 2 fibrosis. Overall, at a median follow-up of 80 months, the rates of good-excellent physician and patient-rated cosmesis were 95% and 85%, respectively, with no difference between patients treated on consecutive vs. every other day. On multivariate analysis, patients who did not receive any adjuvant therapy were at increased risk of developing a LR. Five-year OS, LRFS, and DFS were 97.2%, 97.7%, and 89.5%, respectively.

CONCLUSIONS

Five-fraction APBI delivered primarily in the prone position either daily or every other day was effective with low rates of local recurrence, minimal toxicity, and excellent cosmesis at long-term follow-up.

Omission of radiation therapy after breast conserving surgery for older women at low-risk of local recurrence: One option among many

This editorial discusses the evolving landscape of early-stage breast cancer treatment, emphasizing the need to tailor therapies based on disease biology and genomic approaches. The focus is on the reconsideration of postoperative radiation therapy (RT) for older patients with low-risk, hormone receptor-positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) breast cancer. Recent trials show modest long-term local recurrence rates with the omission of RT after BCS in certain cases, challenging the traditional approach. The commentary calls for continued research on predictive tests for treatment response and advocates for a multidisciplinary approach to decision-making, considering factors like quality of life. The nuanced risk/benefit ratio of RT in older patients is explored, emphasizing the importance of comprehensive assessment for optimal therapy.

Accelerated Partial Breast Irradiation Using 5 Daily Fractions: A Prospective, Phase 2, Multicenter Trial of Cosmetic Outcomes and Toxicity-ACCEL Final Results

PURPOSE

This study investigated the cosmetic degradation and toxicity for an accelerated partial breast irradiation (APBI) prescription delivered in 5 fractions over 1 week and compared the outcomes with those of whole breast irradiation (WBI).

METHODS AND MATERIALS

The trial was a multicenter, single-arm, phase 2 prospective cohort study. Eligible women 50 years of age or older with estrogen receptor-positive and human epidermal growth factor receptor 2-negative invasive ductal carcinoma or ductal carcinoma in situ after breast-conserving surgery received 27 Gy in 5 daily fractions of APBI. The primary endpoint was noninferiority of 2-year cosmesis using the RAPID trial's WBI arm as the control arm. A global consensus cosmetic score using a European Organisation for Research and Treatment of Cancer rating scale score of excellent, good, fair, or poor for each patient at baseline and 2 years was generated by a panel of 5 radiation oncologists using photographs of treated and untreated breasts.

RESULTS

From 2016 to 2019, 298 eligible women were enrolled. By the 2-year follow-up, 76 patients had been lost or withdrawn and 3 had died, resulting in 219 patients available for complete, 2-year photographic cosmetic evaluation. The median follow-up for all participants was 4.7 years (IQR, 3.8-5.5 years). No patient had a fair or poor cosmetic score at the 2-year evaluation. Cosmesis was better or unchanged for 97% of patients and worse for 3% (excellent to good), and no cosmetic failures occurred. The confidence intervals were 0.88 (0.86-0.90) and 1.00 (0.99-1.00) for the RAPID and ACCEL trials, respectively.

CONCLUSIONS

Cosmetic degradation with 5 daily treatments of the ACCEL trial's APBI intervention is noninferior to the WBI arm of the RAPID trial.

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.

Toxicity of external beam accelerated partial-breast irradiation (APBI) in adjuvant therapy of early-stage breast cancer: prospective randomized study

BACKGROUND

Accelerated partial breast irradiation (APBI) is an alternative breast-conserving therapy approach where radiation is delivered in less time compared to whole breast irradiation (WBI), resulting in improved patient convenience, less toxicity, and cost savings. This prospective randomized study compares the external beam APBI with commonly used moderate hypofractionated WBI in terms of feasibility, safety, tolerance, and cosmetic effects.

METHODS

Early breast cancer patients after partial mastectomy were equally randomized into two arms- external APBI and moderate hypofractionated WBI. External beam technique using available technical innovations commonly used in targeted hypofractionated radiotherapy to minimize irradiated volumes was used (cone beam computed tomography navigation to clips in the tumor bed, deep inspiration breath hold technique, volumetric modulated arc therapy dose application, using flattening filter free beams and the six degrees of freedom robotic treatment couch). Cosmetics results and toxicity were evaluated using questionnaires, CTCAE criteria, and photo documentation.

RESULTS

The analysis of 84 patients with a median age of 64 years showed significantly fewer acute adverse events in the APBI arm regarding skin reactions, local and general symptoms during a median follow-up of 37 months (range 21-45 months). A significant difference in favor of the APBI arm in grade ≥ 2 late skin toxicity was observed (p = 0.026). Late toxicity in the breast area (deformation, edema, fibrosis, and pain), affecting the quality of life and cosmetic effect, occurred in 61% and 17% of patients in WBI and APBI arms, respectively. The cosmetic effect was more favorable in the APBI arm, especially 6 to 12 months after the radiotherapy.

CONCLUSION

External APBI demonstrated better feasibility and less toxicity than the standard regimen in the adjuvant setting for treating early breast cancer patients. The presented study confirmed the level of evidence for establishing the external APBI in daily clinical practice.

TRIAL REGISTRATION

NCT06007118.

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.

Cosmetic Outcome and Toxicity After Stereotactic Accelerated Partial Breast Irradiation in Early Breast Cancer: A Prospective Observational Cohort Study

PURPOSE

The aim of this work was to prospectively evaluate the toxicity and cosmetic outcomes of 5-fraction, stereotactic, accelerated partial breast irradiation (APBI).

METHODS AND MATERIALS

This prospective observational cohort study enrolled women who underwent APBI for invasive carcinoma or carcinoma in situ of the breast. APBI was delivered using a CyberKnife M6 robotic radiosurgery system at 30 Gy in 5 nonconsecutive, once-daily fractions. Women undergoing whole breast irradiation (WBI) were also enrolled for comparison. Patient-reported and physician-assessed adverse events were recorded. Breast fibrosis was measured using a tissue compliance meter, and breast cosmesis was assessed using BCCT.core (an automatic, computer-based software). Outcomes were collected until 24 months posttreatment according to the study protocol.

RESULTS

In total, 204 patients (APBI, n = 103; WBI, n = 101) were enrolled. Regarding patient-reported outcomes, the APBI group reported significantly less skin dryness (6.9% vs 18.3%; P = .015), radiation skin reaction (9.9% vs 23.5%; P = .010), and breast hardness (8.0% vs 20.4%; P = .011) at 6 months than the WBI group. On physician assessment, the APBI group had significantly less dermatitis at 12 months (1.0% vs 7.2%; P = .027) than the WBI group. Any severe toxicities after APBI were rare in patient-reported outcomes (score ≥3, 3.0%) and physician assessments (grade ≥3, 2.0%). In the uninvolved quadrants, measured fibrosis in the APBI group was significantly lower than that in the WBI group at 6 (P = .001) and 12 (P = .029) months but not at 24 months. In the involved quadrant, measured fibrosis in the APBI group was not significantly different from that in the WBI group at any time. Cosmetic outcomes in the APBI group were mostly excellent or good (77.6%) at 24 months, and there was no significant cosmetic detriment from the baseline.

CONCLUSIONS

Stereotactic APBI was associated with less fibrosis in the uninvolved breast quadrants than WBI. Patients showed minimal toxicity and no detrimental effects on cosmesis after APBI.

One-week external beam partial breast irradiation: survival and toxicity outcomes

PURPOSE

According to ASTRO and ESTRO guidelines, external beam Partial Breast Irradiation (PBI) is a valid option for early-stage breast cancer patients. Nevertheless, there is lack of consensus about the best treatment schedule.

METHODS

We retrospectively analysed data of female patients treated at our institution from 2013 to 2022 with adjuvant "one-week" partial breast irradiation. Clinical Target Volume (CTV) was an isotropic expansion of 15 mm from the tumour bed (identified as the breast tissue between surgical clips). The treatment schedule was 30 Gy delivered with Volumetric Modulated Arc Therapy in 5 daily fractions. The primary endpoint was Local Control (LC). Disease-Free Survival (DFS), Overall Survival (OS) and safety were secondary endpoints.

RESULTS

Three hundred and forty-four patients with a median age of 69 (33-87) years were included in the study. After a median follow-up of 34 (7-105) months, 7 patients (2.0%) developed a local recurrence. Three-year LC, DFS and OS actuarial rates were 97.5% (95% CI 96.2%-98.8%), 95.7% (95% CI 94.2%-97.2%), and 96.9% (95% CI 95.7%-98.1%), respectively. Ten (2.9%) patients experienced grade 2 late toxicities. Five (1.5%) patients reported late cardiac major events. Three (0.9%) late pulmonary toxicities were detected. One hundred and five (30.5%) patients reported fat necrosis. Good or excellent cosmetic evaluation following the Harvard Scale was reported in 252 (96.9%) cases by the physicians, while in 241 (89.2%) cases by the patients.

CONCLUSION

"One-week" PBI is effective and safe, and this schedule is a valid option for highly selected early breast cancer patients.

Advances in Radiotherapy for Breast Cancer

Breast cancer is the most prevalent cancer in women, and the second leading cause of cancer death in women in the United States. Radiation therapy is an important component in the multimodal management of breast cancer, including early stage and locally advanced breast cancers, as well as metastatic cases. Breast cancer radiation therapy has seen significant advancements over the past 20 years. This article discusses the latest advances in the radiotherapeutic management of breast cancer, especially focusing on the technological advances in radiation treatment planning and techniques that have exploited the understanding of radiation biology.

Five Fraction External Beam Partial Breast Irradiation: A User's Guide

OBJECTIVE

Mature follow up from multiple randomized trials have demonstrated the safety and efficacy of external beam partial breast irradiation (PBI) for appropriately selected patients with early stage breast cancer. Despite this evidence, external beam PBI remains underutilized. In this user guide we outline patient selection, workflow, and address possible challenges to aid in implementation of evidence-based external beam PBI.

MATERIALS AND METHODS

Review of the current guidelines for PBI suitability, surgical considerations, treatment technique, simulation, contouring, and treatment planning, citing the latest published literature to support PBI utilization.

RESULTS

Prospective data supports the use of 30 Gy in 5 fractions delivered with intensity modulated radiation therapy on a daily or every other day basis for a significant proportion of early stage breast cancer patients. The surgical cavity must be clearly visualized on treatment planning scan, recommend 3-5 weeks post-operatively, and the recommended clinical target volume expansion on the surgical cavity is 0.5-1.0 cm. A planning target volume expansion, based on motion management and image guidance, of 0.5-1.0 cm should be used. Organ at risk dose constraints of heart V3Gy ≤10% and contralateral breast Dmax ≤1 Gy are often achievable.

CONCLUSIONS

Five fraction external beam PBI is a highly effective treatment with very limited toxicity for patients with early stage breast cancer following breast conserving surgery. Commonly utilized intensity modulated treatment planning techniques with plan delivery on standard linear accelerators results significant normal tissue sparing and makes implementation feasible at most radiation oncology centers.

Accelerated Partial Breast Irradiation: Florence Phase 3 Trial Experience and Future Perspectives

Accelerated partial breast irradiation Florence phase 3 trial is a single-center study comparing intensity-modulated based accelerated partial breast irradiation (PBI, 30 Gy in 5 fractions) and whole breast irradiation (50 Gy in 25 fractions) followed by a tumor bed boost (10 Gy in 5 fractions). This easy-to-deliver PBI approach showed excellent long-term disease control with favorable safety and cosmetic outcome profiles. A plateau has been probably reached concerning the reduction of the number of fractions in the postoperative PBI setting. A 5-fraction schedule is the standard regimen and probably the appropriate compromise in terms of efficacy, safety, and quality of life, also considering the negative results of most intraoperative single-fraction PBI trials. A new frontier is now open on the potential benefit of preoperative PBI delivery, although concerns remain on the optimal dose, fractionation, and technique. Hereby we report the accelerated PBI Florence phase 3 trial experience and future perspectives.