Ultra-Hypofractionation for Whole-Breast Irradiation in Early Breast Cancer: Interim Analysis of a Prospective Study

Volumetric Modulated Arc Therapy for 26 Gy in 5 Fractions Whole Breast Irradiation for Breast Cancer

Purpose

To report the dosimetric and toxicity outcomes of patients treated with 26 Gy in 5 fractions ultrahypofractionated (uHF) whole breast irradiation (WBI) using volumetric arc therapy (VMAT).

Methods and Materials

We identified 476 consecutive patients who underwent WBI using VMAT-uHF between 2020 and 2021. Study endpoints included acute toxicity and dosimetric parameters for target volume and organs at risk. The dosimetric results were compared with a historical cohort at the same institution who were treated with moderately hypofractionated WBI using 3-dimensional (3D)-conformal radiation therapy (3D-CRT, n = 392), with the total dose rescaled to 26 Gy.

Results

VMAT-uHF achieved a mean D95% and Dmax of the planning target volume of 96.2% and 102.8% of the prescribed dose, respectively. The VMAT-uHF group demonstrated significantly superior planning target volume coverage and improved dose homogeneity, with a 30.6% higher D95 and a 0.7% lower Dmax compared with the 3D-CRT group (both P < .05). Mean doses for the ipsilateral lung and heart were 3.12 ± 4.59 Gy and 0.92 ± 0.25 Gy, respectively, showing differences of < 0.3 Gy compared with the 3D-CRT group. The VMAT-uHF group exhibited a significantly lower left anterior descending artery Dmax (-3.73 Gy), while the contralateral breast showed a higher Dmean (+1.43 Gy), compared with the 3D-CRT group. Acute toxicity following VMAT-uHF was predominantly mild, with grade 1 toxicity observed in 114 out of 120 patients. No additional toxicities were reported after a median follow-up of 21.2 months.

Conclusions

The application of VMAT in ultrahypofractionation can enhance target coverage while maintaining radiation doses to organs at risk low, albeit with an increase in contralateral breast dose compared with 3D-CRT. Given the low toxicity profile observed in our cohort with VMAT-uHF, the clinical significance of these dosimetric differences requires further investigation.

Exploring the feasibility of preoperative tumor-bed boost, oncoplastic surgery, and adjuvant radiotherapy schedule in early-stage breast cancer: a phase II clinical trial

BACKGROUND

Oncoplastic breast-conserving surgery (OBCS) improves satisfaction in patients who would fare otherwise sub-optimal cosmetic outcomes while bringing challenges in tumor-bed identification during adjuvant radiotherapy. The ultra-hypofractionated breast radiotherapy further shortens treatment sessions from moderately hypofractionated regimens. To circumscribe the difficulty in tumor-bed contouring and the additional toxicity from larger boost volumes, the authors, propose to move forward with the boost session preoperatively from the adjuvant radiation part. Thus, the present study aims to evaluate the feasibility of a new treatment paradigm of preoperative primary-tumor boost before breast-conserving surgery (BCS) or OBCS followed by adjuvant ultra-hypofractionated whole-breast irradiation (u-WBRT) for patients with early-stage breast cancer.

METHODS

There was a phase II study. Patients younger than 55 years old, with a biopsy confirmed mono-centric breast cancer, without lymph node involvement were enrolled. A preoperative primary-tumor boost was given by a single 10 Gy in 1 fraction, and BCS or OBCS was conducted within 2 weeks afterwards. Adjuvant u-WBRT (26 Gy/5.2 Gy/5 f) was given in 6 weeks postoperatively without any boost, after the full recovery from surgery. Surgical complications and patient-reported outcomes, as assessed via Breast-Q questionnaires, were documented. A propensity score matching approach was employed to identify a control group at a 1:1 ratio for BREAST-Q outcomes comparison.

RESULTS

From May 2022 to September 2023, 36 patients were prospectively enrolled. Surgical complications were observed in seven cases (19.4%), including three cases with Clavien-Dindo (CD) grade 1-2 and four cases with CD grade 3 complications. All but four patients (11.1%) started the planned u-WBRT within 1 week after the predefined due dates postoperatively (≤49 days). Four patients (11.1%) developed grade 2 radiodermatitis after chemotherapy initiation. Compared to the study group, the control patients reported higher scores in chest physical well-being ( P =0.045) and in their attitudes towards arm swelling ( P =0.01). No significant difference was detected in the other of domains (Satisfaction with Breasts, Sexual and Psychosocial Well-Being, and Adverse Effects of Radiation). With a median follow-up period of 9.8 months (2.4-18.9 months), none had any sign of relapse.

CONCLUSION

This Phase II clinical trial confirmed the technical and safety feasibility of a novel radiation schedule in patients undergoing BCS or OBCS. According to the BREAST-Q questionnaire, patients who underwent novel radiation schedules reported lower satisfaction in chest physical well-being. A randomized controlled trial is necessary to further investigate these findings. Additionally, long-term follow-up is required to assess oncological outcomes.

Feasibility and Safety of the "One-Week Breast Radiation Therapy" Program

AIMS

FAST-Forward and UK-FAST-trials have demonstrated the safety and efficacy of five-fraction breast adjuvant radiation therapy (RT) and have become the standard of care for selected early breast cancer patients. In response to the additional burden caused by the COVID-19 pandemic, we implemented "One-Week Breast RT," an innovative program delivering five-fraction whole breast RT in a complete 5-day workflow. The primary objective of this study was to demonstrate the feasibility and safety of our program. The secondary objective was to evaluate cosmetic results.

MATERIAL AND METHODS

A total of 120 patients treated from February 2021 to March 2022, received whole breast RT without lymph node irradiation nor boost, with 26 Gy in five fractions over one week. Inverse planning with restricted optimization parameters offers systematic deep inspiration breath-hold aimed to provide treatment plans compliant with FAST-Forward recommendations. Toxicity and cosmetic evaluations were prospectively registered prior (pre-RT), at the end (end-RT), and 6 months after RT (6 months) based on Common Terminology Criteria for Adverse Events v. 4.03 and Harvard scale.

RESULTS

With a median age of 70 years (interquartile range (IQR): 66-74) and a median follow-up of 6 months (IQR: 6.01-6.25), most patients (93.3%) completed their RT in one week from baseline to the end of the treatment consultation. The most common acute toxicities (at end-RT) were skin-related: radio-dermatitis (72%), induration (35%), hyperpigmentation (8%), and breast edema (16%). The rate of radio-dermatitis decreased from end-RT to 6 months (71.7% vs 5.4%, P< 0.001). No patient experienced grade ≥3 toxicity. At 6 months, cosmetic results were generally good or excellent (94.1%).

CONCLUSION

This study confirms the feasibility and acute safety of the "One-Week Breast RT" in real life. Favorable toxicity profiles and good cosmetic outcomes are in line with FAST-Forward results. A prospective national cohort, aimed at decreasing treatment burden, maintaining safety, efficacy, and improving RT workflow efficiency with longer follow-up is ongoing.

Acute adverse events of ultra-hypofractionated whole-breast irradiation after breast-conserving surgery for early breast cancer in Japan: an interim analysis of the multi-institutional phase II UPBEAT study

BACKGROUND

The applicability of ultra-hypofractionated (ultra-HF) whole-breast irradiation (WBI) remains unknown in Japanese women. This study aimed to evaluate the safety and efficacy of this approach among Japanese women and report the results of an interim analysis performed to assess acute adverse events (AEs) and determine whether it was safe to continue this study.

METHODS

We enrolled Japanese women with invasive breast cancer or ductal carcinoma in situ who had undergone breast-conserving surgery, were aged ≥ 40 years, had pathological stages of Tis-T3 N0-N1, and had negative surgical margins. Ultra-HF-WBI was delivered at 26 Gy in five fractions over one week. When the number of enrolled patients reached 28, patient registration was paused for three months. The endpoint of the interim analysis was the proportion of acute AEs of grade ≥ 2 (Common Terminology Criteria for Adverse Events v5.0) within three months.

RESULTS

Of the 28 patients enrolled from seven institutes, 26 received ultra-HF-WBI, and 2 were excluded due to postoperative infections. No AEs of grade ≥ 3 occurred. One patient (4%) experienced grade 2 radiation dermatitis, and 18 (69%) had grade 1 radiation dermatitis. The other acute grade 1 AEs experienced were skin hyperpigmentation (n = 10, 38%); breast pain (n = 4, 15%); superficial soft tissue fibrosis (n = 3, 12%); and fatigue (n = 1, 4%). No other acute AEs of grade ≥ 2 were detected.

CONCLUSIONS

Acute AEs following ultra-HF-WBI were within acceptable limits among Japanese women, indicating that the continuation of the study was appropriate.

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.

Ultra-hypofractionated one-week locoregional radiotherapy for patients with early breast cancer: Acute toxicity results

Purpose

Moderate hypofractionated radiotherapy is the standard of care for all patients with breast cancer, irrespective of stage or prior treatments. While extreme hypofractionation is accepted for early-stage tumours, its application in irradiating locoregional lymph nodes remains controversial.

Materials and methods

A prospective registry analysis from July 2020 to September 2023 included 276 patients with early-stage breast cancer treated with one-week ultra-hypofractionation (UHF) at 26 Gy in 5 fractions on the whole breast (58.3 %) or thoracic wall (41.7 %) and ipsilateral regional lymph nodes and simultaneous integrated boost (58.3 %). Primary endpoint was assessment of acute adverse events (AEs). Secondarily, onset of early-delayed toxicity was assessed. A minimum 6-month follow-up was required for assessing potential treatment-related early-delayed complications. Acute or late complications attributable to treatment were assessed at inclusion using the Common Terminology Criteria for Adverse Events (CTCAE) v5.0 criteria.

Results

With a median follow-up of 19 months (range 1-49 months), 159 (57.6 %) patients reported AEs, predominantly grade (G) 1 (n = 139, 50.4 %) and G2 (n = 20, 7.8 %). Skin acute toxicity was common (G1/2: 134, G3: 14), while breast oedema occurred in 10 patients (G1: 9, G2: 1), and 15.9 % reported breast pain (G1: 42, G2: 2). Ipsilateral arm oedema was observed in 1.8 % patients. For patients with a follow-up beyond 6 months (n = 213), 23.4 % patients reported G1/G2 skin AEs, 8.8 % had G1/G2 breast/chest wall oedema, and 8.9 % experienced arm lymphedema. There were no cases of brachial plexopathy or G3 toxicity in this group of patients.

Conclusions

One-week UHF adjuvant locoregional radiation is well-tolerated, displaying low-toxicity profiles comparable to other studies using similar irradiation schedules.

In vivo dose measurements for tangential field-in-field ultra-hypofractionated breast radiotherapy

INTRODUCTION

Ultra-hypofractionated radiotherapy (UHF-RT) mandates more accuracy in each part of the treatment cycle to maximize cure rates and minimize toxicities. In vivo dosimetry is a direct method for verifying overall treatment accuracy. This study evaluated uncertainties in the delivered dose of Hypofractionated (HF) and UHF Whole Breast Irradiation (WBI) and to analyze the accuracy of the workflow to pave the way for a wide-scale use of UHF-RT.

METHODS

Thirty-three breast cancer cases, including 16 HF-WBI and 17 UHF-WBI were treated with 3D conformal Radiotherapy (3D-CRT), where 79 fields were analyzed for dose verification. The measurement point was set at the beam entrance (1.5 cm depth). The expected dose at Dmax was calculated via TPS. Before in vivo measurements, diode detectors were tested and calibrated. We developed initial validation measurements for UHF-RT on an anthropomorphic breast phantom for the first time.

RESULTS

For RANDO phantom, the percentage difference between measured and calculated doses showed an average of -0.52 ± 5.4%, in addition to an excellent dose reproducibility within 0.6%. The overall in vivo measurements for studied cases showed that 83.5% of the measured doses were within ±5% and only 1.8% of the measured doses were greater than ±10% of the calculated doses. The percentage accuracy was slightly larger for UHF cohort (84.2%) compared to HF cohort (83.2%). The maximum percentage difference between them was less than 1%.

CONCLUSION

Breast in vivo dosimetry is an adequate tool for treatment verification that improves the accuracy of the treatment cycle. UHF-RT may contribute in reducing the long waiting lists, increasing patient convenience, and saving the available resources for breast cancer patients.

Large scale experience of two ultrahypofractionated 5 fractions regimes after breast conserving surgery from a single centre

PURPOSE

Ultra-hypofractionation breast radiotherapy is a safe alternative to moderate hypofractionation. This study reports the results of two ultrahypofractionated regimens used in clinical practice in a high-volume radiotherapy center in terms of efficacy and of tolerance.

METHODS

we included all patients treated in an adjuvant setting with five fractions after breast conserving surgery (BCS), for a histologically-confirmed invasive or in situ breast carcinoma. Radiotherapy regimens after BCS were either a 5-week schedule with 5 weekly fractions of 5,7 Gy or a one-week schedule with 5 daily fractions of 5,2 Gy. Adverse events were recorded and local-relapse free survival (LRFS), locoregional-relapse free survival (LRRFS), metastasis-free survival (MFS), for breast-cancer specific survival (BCSS) and overall survival (OS) were evaluated.

RESULTS

Between December 2014 and December 2022, 396 patients (400 breasts) were treated with ultrahypofractionated radiotherapy. Five-year LRFS was 98.8% (95% confidence interval: 97.1%-100%), and 5-year OS was 96.0% (95%CI: 92.6-99.5%). Age was statistically associated with OS in univariate analysis (HR: 1.16, 95%CI: 1.04-1.42, p = .01). Four patients (1.0%) experienced acute grade 3 radiation-induced adverse events, and 8 patients (2.3%) acute grade 2 toxicities. Twenty-three patients (5.8%) experienced late toxicity, all of them being graded as grade 1. The use of the 5.7 Gy-weekly-fraction regimen and the delivery of a tumor bed boost were significantly associated with acute radiodermatitis (p < .01; p = .02; respectively) and late fibrosis (p < .01; p = .049; respectively).

CONCLUSIONS

ultrahypofractionated radiotherapy was associated with an excellent tumor control rate in our 'real-life' cohort with low-risk breast cancer patients. However, delivery of a tumor bed boost and using weekly 5.7-Gy fractions were associated with an increased risk of acute and late cutaneous toxicities.

Acute skin toxicity of ultra-hypofractionated whole breast radiotherapy with simultaneous integrated boost for early breast cancer

Background

Whole-breast irradiation (WBI) after breast conserving surgery (BCS) is indicated to improve loco-regional control and survival. Former studies showed that addition of tumor bed boost in all age groups significantly improved local control although no apparent impact on overall survival but with an increased risk of worse cosmetic outcome. Even though shortened regimens in 3 weeks are considered the standard, recent studies have shown the non-inferiority of a treatment regimen of 5 fractions in one-week in both locoregional control and toxicity profile, although simultaneous integrated boost (SIB) in this setting has been scarcely studied.

Materials and Methods

From March-2020 to March-2022, 383 patients with early breast cancer diagnosis and a median age of 56 years-old (range 30-99)were included in a prospective registry of ultra-hypofractionated WBI up to a total dose of 26 Gy in 5.2 Gy/fraction with a SIB of 29 Gy in 5.8 Gy/fraction in 272 patients (71%), 30-31 Gy in 6-6.2 Gy/fraction in 111 patients (29%) with close/focally affected margins. Radiation treatment was delivered by conformal 3-D technique in 366 patients (95%), VMAT in 16patients (4%) and conformal 3-D with deep inspiration breath hold (DIBH) in 4patients (1%). Ninety-three per cent of patients received endocrine therapy and 43% systemic or targeted chemotherapy. Development of acute skin complications was retrospectively reviewed.

Results

With a median follow-up of 18 months (range 7-31), all patients are alive without evidence of local, regional or distant relapse. Acute tolerance was acceptable, with null o mild toxicity: 182 (48%) and 15 (4%) patients developed skin toxicity grade 1 and 2 respectively; 9 (2%) and 2 (0.5%) patients breast edema grade 1and 2 respectively. No other acute toxicities were observed. We also evaluated development of early delayed complications and observed grade 1 breast edema in 6 patients (2%); grade 1 hyperpigmentation in 20 patients (5%); and grade 1 and 2 breast induration underneath boost region in 10(3%) and 2 patients (0.5%) respectively. We found a statistically significant correlation between the median PTVWBI and presence of skin toxicity (p = 0.028) as well as a significant correlation between late hyperpigmentation with the median PTVBOOST (p = 0.007) and the ratio PTVBOOST/PTVWBI (p = 0.042).

Conclusion

Ultra-hypofractionated WBI + SIB in 5 fractions over one-week is feasible and well tolerated, although longer follow-up is necessary to confirm these results.