Partial-breast radiotherapy after breast conservation surgery for patients with early breast cancer (UK IMPORT LOW trial): 5-year results from a multicentre, randomised, controlled, phase 3, non-inferiority trial

Protocol for the T-REX-trial: tailored regional external beam radiotherapy in clinically node-negative breast cancer patients with 1-2 sentinel node macrometastases - an open, multicentre, randomised non-inferiority phase 3 trial

INTRODUCTION

Modern systemic treatment has reduced incidence of regional recurrences and improved survival in breast cancer (BC). It is thus questionable whether regional radiotherapy (RT) is still beneficial in patients with sentinel lymph node (SLN) macrometastasis. Postoperative regional RT is associated with an increased risk of arm morbidity, pneumonitis, cardiac disease and secondary cancer. Therefore, there is a need to individualise regional RT in relation to the risk of recurrence.

METHODS AND ANALYSIS

In this multicentre, prospective randomised trial, clinically node-negative patients with oestrogen receptor-positive, HER2-negative BC and 1-2 SLN macrometastases are eligible. Participants are randomly assigned to receive regional RT (standard arm) or not (intervention arm). Regional RT includes the axilla level I-III, the supraclavicular fossa and in selected patients the internal mammary nodes. Both groups receive RT to the remaining breast. Chest-wall RT after mastectomy is given in the standard arm, but in the intervention arm only in cases of widespread multifocality according to national guidelines. RT quality assurance is an integral part of the trial.The trial aims to include 1350 patients between March 2023 and December 2028 in Sweden and Norway. Primary outcome is recurrence-free survival (RFS) at 5 years. Non-inferiority will be declared if outcome in the de-escalation arm is not >4.5 percentage units below that with regional RT, corresponding to an HR of 1.41 assuming 88% 5-year RFS with standard treatment. Secondary outcomes include locoregional recurrence, overall survival, patient-reported arm morbidity and health-related quality of life. Gene expression analysis and tumour tissue-based studies to identify prognostic and predictive markers for benefit of regional RT are included.

ETHICS AND DISSEMINATION

The trial protocol is approved by the Swedish Ethics Authority (Dnr-2022-02178-01, 2022-05093-02, 2023-00826-02, 2023-03035-02). Results will be presented at scientific conferences and in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT05634889.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Long-Term Results of Intraoperative Radiation Therapy for Early Breast Cancer Using a Nondedicated Linear Accelerator

Purpose

To present the long-term results of intraoperative radiation therapy (IORT) for early breast cancer using a nondedicated linear accelerator.

Methods and Materials

The eligibility criteria were biopsy-proven invasive carcinoma, age ≥40 years, tumor size ≤3 cm, and N0M0. We excluded multifocal lesions and sentinel lymph node involvement. All patients had previously undergone breast magnetic resonance imaging. Breast-conserving surgery with margins and sentinel lymph node evaluation using frozen sections were performed in all cases. If there were no margins or involved sentinel lymph nodes, the patient was transferred from the operative suite to the linear accelerator room, where IORT was delivered (21 Gy).

Results

A total of 209 patients who were followed up for ≥1.5 years from 2004 to 2019 were included. The median age was 60.3 years (range, 40-88.6), and the mean pT was 1.3 cm (range, 0.2-4). There were 90.5% pN0 cases (7.2% of micrometastases and 1.9% of macrometastases). Ninety-seven percent of the cases were margin free. The rate of lymphovascular invasion was 10.6%. Twelve patients were negative for hormonal receptors, and 28 patients were HER2 positive. The median Ki-67 index was 29% (range, 0.1-85). Intrinsic subtype stratification was as follows: luminal A, 62.7% (n = 131); luminal B, 19.1% (n = 40); HER2 enriched 13.4% (n = 28); and triple negative, 4.8% (n = 10). Within the median follow-up of 145 months (range, 12.8-187.1), the 5-year, 10-year, and 15-year overall survival rates were 98%, 94.7%, and 88%, respectively. The 5-year, 10-year, and 15-year disease-free rates were 96.3%, 90%, and 75.6%, respectively. The 15-year local recurrence-free rate was 76%. Fifteen local recurrences (7.2%) occurred throughout the follow-up period. The mean time to local recurrence was 145 months (range, 12.8-187.1). As a first event, 3 cases of lymph node recurrence, 3 cases of distant metastasis, and 2 cancer-related deaths were recorded. Tumor size >1 cm, grade III, and lymphovascular invasion were identified as risk factors.

Conclusions

Despite approximately 7% of recurrences, we may infer that IORT may still be a reasonable option for selected cases. However, these patients require a longer follow-up as recurrences may occur after 10 years.

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.

Whole Breast Irradiation in Comparison to Endocrine Therapy in Early Stage Breast Cancer-A Direct and Network Meta-Analysis of Published Randomized Trials

BACKGROUND

Multiple randomized trials have established adjuvant endocrine therapy (ET) and whole breast irradiation (WBI) as the standard approach after breast-conserving surgery (BCS) in early-stage breast cancer. The omission of WBI has been studied in multiple trials and resulted in reduced local control with maintained survival rates and has therefore been adapted as a treatment option in selected patients in several guidelines. Omitting ET instead of WBI might also be a valuable option as both treatments have distinctly different side effect profiles. However, the clinical outcomes of BCS + ET vs. BCS + WBI have not been formally analyzed.

METHODS

We performed a systematic literature review searching for randomized trials comparing BCS + ET vs. BCS + WBI in low-risk breast cancer patients with publication dates after 2000. We excluded trials using any form of chemotherapy, regional nodal radiation and mastectomy. The meta-analysis was performed using a two-step process. First, we extracted all available published event rates and the effect sizes for overall and breast-cancer-specific survival (OS, BCSS), local (LR) and regional recurrence, disease-free survival, distant metastases-free interval, contralateral breast cancer, second cancer other than breast cancer and mastectomy-free interval as investigated endpoints and compared them in a network meta-analysis. Second, the published individual patient data from the Early Breast Cancer Trialists' Collaborative Group (EBCTCG) publications were used to allow a comparison of OS and BCSS.

RESULTS

We identified three studies, including a direct comparison of BCS + ET vs. BCS + WBI (n = 1059) and nine studies randomizing overall 7207 patients additionally to BCS only and BCS + WBI + ET resulting in a four-arm comparison. In the network analysis, LR was significantly lower in the BCS + WBI group in comparison with the BCS + ET group (HR = 0.62; CI-95%: 0.42-0.92; p = 0.019). We did not find any differences in OS (HR = 0.93; CI-95%: 0.53-1.62; p = 0.785) and BCSS (OR = 1.04; CI-95%: 0.45-2.41; p = 0.928). Further, we found a lower distant metastasis-free interval, a higher rate of contralateral breast cancer and a reduced mastectomy-free interval in the BCS + WBI-arm. Using the EBCTCG data, OS and BCSS were not significantly different between BCS + ET and BCS + WBI after 10 years (OS: OR = 0.85; CI-95%: 0.59-1.22; p = 0.369) (BCSS: OR = 0.72; CI-95%: 0.38-1.36; p = 0.305).

CONCLUSION

Evidence from direct and indirect comparison suggests that BCS + WBI might be an equivalent de-escalation strategy to BCS + ET in low-risk breast cancer. Adverse events and quality of life measures have to be further compared between these approaches.

Recent advances progress in radiotherapy for breast cancer after breast-conserving surgery: a review

Adjuvant radiotherapy after breast-conserving surgery has become an integral part of the treatment of breast cancer. In recent years, the development of radiotherapy technology has made great progress in this field, including the comparison of the curative effects of various radiotherapy techniques and the performance of the segmentation times. The choice of radiotherapy technology needs to be co-determined by clinical evidence practice and evaluated for each individual patient to achieve precision radiotherapy. This article discusses the treatment effects of different radiotherapy, techniques, the risk of second cancers and short-range radiation therapy techniques after breast-conserving surgery such as hypo fractionated whole breast irradiation and accelerated partial breast irradiation. The choice of radiotherapy regimen needs to be based on the individual condition of the patient, and the general principle is to focus on the target area and reduce the irradiation of the normal tissues and organs. Short-range radiotherapy and hypofractionated are superior to conventional radiotherapy and are expected to become the mainstream treatment after breast-conserving surgery.

Concurrent chemotherapy with partial breast irradiation in triple negative breast cancer patients may improve disease control compared with sequential therapy

Purpose

To report outcomes on a subset of patients with triple negative breast cancer (TNBC) treated on prospective trials with post-lumpectomy partial breast irradiation and concurrent chemotherapy (PBICC) and compare them to a retrospectively assessed similar cohort treated with whole breast irradiation after adjuvant chemotherapy (WBIaC).

Methods and materials

Women with T1-2, N0-1 invasive breast cancer with ≥ 2mm lumpectomy margins were offered therapy on one of two PBICC trials. PBI consisted of 40.5 Gy in 15 daily 2.7 Gy fractions delivered concurrently with the first 2 cycles of adjuvant chemotherapy. The comparison cohort received WBI to a median dose of 60.7 Gy, (including boost, range 42.5 - 66 Gy), after completion of non-concurrent, adjuvant chemotherapy. We evaluated disease-free survival (DFS), and local/loco-regional/distant recurrence-free survival (RFS). We compared survival rates using Kaplan-Meier curves and log-rank test of statistical significance.

Results

Nineteen patients with TNBC were treated with PBICC on prospective protocol, and 49 received WBIaC. At a median follow-up of 35.5 months (range 4.8-71.9), we observed no deaths in the PBICC cohort and 2 deaths in the WBIaC cohort (one from disease recurrence). With a median time of 23.4 (range 4.8 to 47) months, there were 7 recurrences (1 nodal, 4 local, 4 distant), all in the WBIaC group. At 5 years, there was a trend towards increased local RFS (100% vs. 85.4%, p=0.17) and loco-regional RFS (100% vs. 83.5, p=0.13) favoring the PBICC cohort. There was no significant difference in distant RFS between the two groups (100% vs. 94.4%, p=0.36). Five-year DFS was 100% with PBICC vs.78.9% (95% CI: 63.2 to 94.6%, p=0.08) with WBIaC.

Conclusion

This study suggests that PBICC may offer similar and possibly better outcomes in patients with TNBC compared to a retrospective cohort treated with WBIaC. This observation is hypothesis-generating for prospective trials.

Secondary breast angiosarcoma following accelerated partial breast irradiation with intracavitary multicatheter applicator brachytherapy

PURPOSE

Secondary angiosarcoma of the breast is a rare complication of breast radiotherapy and is associated with a poor prognosis. There are many reported cases of secondary angiosarcoma following whole breast irradiation (WBI), however development of secondary angiosarcoma following brachytherapy-based accelerated partial breast irradiation (APBI) is not as well characterized.

METHODS AND MATERIALS

We reviewed and reported a case of a patient who developed secondary angiosarcoma of the breast following intracavitary multicatheter applicator brachytherapy APBI.

RESULTS

A 69-year-old female was originally diagnosed with T1N0M0 invasive ductal carcinoma of the left breast and treated with lumpectomy followed by adjuvant intracavitary multicatheter applicator brachytherapy APBI. Seven years following her treatment, she developed secondary angiosarcoma. However, the diagnosis of secondary angiosarcoma was delayed due to nonspecific imaging findings and a negative biopsy.

CONCLUSIONS

Our case highlights the need for secondary angiosarcoma to be considered in the differential diagnosis when patients present with symptoms such as breast ecchymosis and skin thickening following WBI or APBI. Prompt diagnosis and referral to a high-volume sarcoma treatment center for multidisciplinary evaluation is vital.

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.

Dose-escalated simultaneous integrated boost radiotherapy in early breast cancer (IMPORT HIGH): a multicentre, phase 3, non-inferiority, open-label, randomised controlled trial

BACKGROUND

A tumour-bed boost delivered after whole-breast radiotherapy increases local cancer-control rates but requires more patient visits and can increase breast hardness. IMPORT HIGH tested simultaneous integrated boost against sequential boost with the aim of reducing treatment duration while maintaining excellent local control and similar or reduced toxicity.

METHODS

IMPORT HIGH is a phase 3, non-inferiority, open-label, randomised controlled trial that recruited women after breast-conserving surgery for pT1-3pN0-3aM0 invasive carcinoma from radiotherapy and referral centres in the UK. Patients were randomly allocated to receive one of three treatments in a 1:1:1 ratio, with computer-generated random permuted blocks used to stratify patients by centre. The control group received 40 Gy in 15 fractions to the whole breast and 16 Gy in 8 fractions sequential photon tumour-bed boost. Test group 1 received 36 Gy in 15 fractions to the whole breast, 40 Gy in 15 fractions to the partial breast, and 48 Gy in 15 fractions concomitant photon boost to the tumour-bed volume. Test group 2 received 36 Gy in 15 fractions to the whole breast, 40 Gy in 15 fractions to the partial breast, and 53 Gy in 15 fractions concomitant photon boost to the tumour-bed volume. The boost clinical target volume was the clip-defined tumour bed. Patients and clinicians were not masked to treatment allocation. The primary endpoint was ipsilateral breast tumour relapse (IBTR) analysed by intention to treat; assuming 5% 5-year incidence with the control group, non-inferiority was predefined as 3% or less absolute excess in the test groups (upper limit of two-sided 95% CI). Adverse events were assessed by clinicians, patients, and photographs. This trial is registered with the ISRCTN registry, ISRCTN47437448, and is closed to new participants.

FINDINGS

Between March 4, 2009, and Sept 16, 2015, 2617 patients were recruited. 871 individuals were assigned to the control group, 874 to test group 1, and 872 to test group 2. Median boost clinical target volume was 13 cm3 (IQR 7 to 22). At a median follow-up of 74 months there were 76 IBTR events (20 for the control group, 21 for test group 1, and 35 for test group 2). 5-year IBTR incidence was 1·9% (95% CI 1·2 to 3·1) for the control group, 2·0% (1·2 to 3·2) for test group 1, and 3·2% (2·2 to 4·7) for test group 2. The estimated absolute differences versus the control group were 0·1% (-0·8 to 1·7) for test group 1 and 1·4% (0·03 to 3·8) for test group 2. The upper confidence limit for test group 1 versus the control group indicated non-inferiority for 48 Gy. Cumulative 5-year incidence of clinician-reported moderate or marked breast induration was 11·5% for the control group, 10·6% for test group 1 (p=0·40 vs control group), and 15·5% for test group 2 (p=0·015 vs control group).

INTERPRETATION

In all groups 5-year IBTR incidence was lower than the 5% originally expected regardless of boost sequencing. Dose-escalation is not advantageous. 5-year moderate or marked adverse event rates were low using small boost volumes. Simultaneous integrated boost in IMPORT HIGH was safe and reduced patient visits.

FUNDING

Cancer Research UK.

External-Beam-Accelerated Partial-Breast Irradiation Reduces Organ-at-Risk Doses Compared to Whole-Breast Irradiation after Breast-Conserving Surgery

In order to evaluate organ-at-risk (OAR) doses in external-beam-accelerated partial-breast irradiation (APBI) compared to standard whole-breast irradiation (WBI) after breast-conserving surgery. Between 2011 and 2021, 170 patients with early breast cancer received APBI within a prospective institutional single-arm trial. The prescribed dose to the planning treatment volume was 38 Gy in 10 fractions on 10 consecutive working days. OAR doses for the contralateral breast, the ipsilateral, contralateral, and whole lung, the whole heart, left ventricle (LV), and the left anterior descending coronary artery (LAD), and for the spinal cord and the skin were assessed and compared to a control group with real-world data from 116 patients who underwent WBI. The trial was registered at the German Clinical Trials Registry, DRKS-ID: DRKS00004417. Compared to WBI, APBI led to reduced OAR doses for the contralateral breast (0.4 ± 0.6 vs. 0.8 ± 0.9 Gy, p = 0.000), the ipsilateral (4.3 ± 1.4 vs. 9.2 ± 2.5 Gy, p = 0.000) and whole mean lung dose (2.5 ± 0.8 vs. 4.9 ± 1.5 Gy, p = 0.000), the mean heart dose (1.6 ± 1.6 vs. 1.7 ± 1.4 Gy, p = 0.007), the LV V23 (0.1 ± 0.4 vs. 1.4 ± 2.6%, p < 0.001), the mean LAD dose (2.5 ± 3.4 vs. 4.8 ± 5.5 Gy, p < 0.001), the maximum spinal cord dose (1.5 ± 1.1 vs. 4.5 ± 5.7 Gy, p = 0.016), and the maximum skin dose (39.6 ± 1.8 vs. 49.1 ± 5.8 Gy, p = 0.000). APBI should be recommended to suitable patients to minimize the risk of secondary tumor induction and the incidence of consecutive major cardiac events.

Preoperative Partial Breast Irradiation in Patients with Low-Risk Breast Cancer: A Systematic Review of Literature

BACKGROUND

Preoperative instead of standard postoperative partial breast irradiation (PBI) after breast-conserving surgery (BCS) has the advantage of reducing the irradiated breast volume, toxicity, and number of radiotherapy sessions and can allow tumor downstaging. In this review, we assessed tumor response and clinical outcomes after preoperative PBI.

PATIENTS AND METHODS

We conducted a systematic review of studies on preoperative PBI in patients with low-risk breast cancer using the databases Ovid Medline, Embase.com, Web of Science (Core Collection), and Scopus (PROSPERO registration CRD42022301435). References of eligible manuscripts were checked for other relevant manuscripts. The primary outcome measure was pathologic complete response (pCR).

RESULTS

A total of eight prospective and one retrospective cohort study were identified (n = 359). In up to 42% of the patients, pCR was obtained and this increased after a longer interval between radiotherapy and BCS (0.5-8 months). After a maximum median follow-up of 5.0 years, three studies on external beam radiotherapy reported low local recurrence rates (0-3%) and overall survival of 97-100%. Acute toxicity consisted mainly of grade 1 skin toxicity (0-34%) and seroma (0-31%). Late toxicity was predominantly fibrosis grade 1 (46-100%) and grade 2 (10-11%). Cosmetic outcome was good to excellent in 78-100% of the patients.

CONCLUSIONS

Preoperative PBI showed a higher pCR rate after a longer interval between radiotherapy and BCS. Mild late toxicity and good oncological and cosmetic outcomes were reported. In the ongoing ABLATIVE-2 trial, BCS is performed at a longer interval of 12 months after preoperative PBI aiming to achieve a higher pCR rate.

The role of the radiation therapy breast boost in the 2020s

Given that most local relapses of breast cancer occur proximal to the original location of the primary, the delivery of additional radiation dose to breast tissue that contained the original primary cancer (known as a "boost") has been a standard of care for some decades. In the context of falling relapse rates, however, it is an appropriate time to re-evaluate the role of the boost. This article reviews the evolution of the radiotherapy boost in breast cancer, discussing who to boost and how to boost in the 2020s, and arguing that, in both cases, less is more.

The 2022 Assisi Think Tank Meeting: White paper on optimising radiation therapy for breast cancer

The present white paper, referring to the 4th Assisi Think Tank Meeting on breast cancer, reviews state-of-the-art data, on-going studies and research proposals. < 70% agreement in an online questionnaire identified the following clinical challenges: 1: Nodal RT in patients who have a) 1-2 positive sentinel nodes without ALND (axillary lymph node dissection); b) cN1 disease transformed into ypN0 by primary systemic therapy and c) 1-3 positive nodes after mastectomy and ALND. 2. The optimal combination of RT and immunotherapy (IT), patient selection, IT-RT timing, and RT optimal dose, fractionation and target volume. Most experts agreed that RT- IT combination does not enhance toxicity. 3: Re-irradiation for local relapse converged on the use of partial breast irradiation after second breast conserving surgery. Hyperthermia aroused support but is not widely available. Further studies are required to finetune best practice, especially given the increasing use of re-irradiation.

Patient characteristics and clinical factors affecting lumpectomy cavity volume: implications for partial breast irradiation

Introduction

Partial breast irradiation (PBI) has increased in utilization, with the postoperative lumpectomy cavity and clips used to guide target volumes. The ideal timing to perform computed tomography (CT)-based treatment planning for this technique is unclear. Prior studies have examined change in volume over time from surgery but not the effect of patient characteristics on lumpectomy cavity volume. We sought to investigate patient and clinical factors that may contribute to larger postsurgical lumpectomy cavities and therefore predict for larger PBI volumes.

Methods

A total of 351 consecutive women with invasive or in situ breast cancer underwent planning CT after breast-conserving surgery at a single institution during 2019 and 2020. Lumpectomy cavities were contoured, and volume was retrospectively computed using the treatment planning system. Univariate and multivariate analyses were performed to evaluate the associations between lumpectomy cavity volume and patient and clinical factors.

Results

Median age was 61.0 years (range, 30-91), 23.9% of patients were Black people, 52.1% had hypertension, the median body mass index (BMI) was 30.4 kg/m², 11.4% received neoadjuvant chemotherapy, 32.5% were treated prone, mean interval from surgery to CT simulation was 54.1 days ± 45.9, and mean lumpectomy cavity volume was 42.2 cm³ ± 52.0. Longer interval from surgery was significantly associated with smaller lumpectomy cavity volume on univariate analysis, p = 0.048. Race, hypertension, BMI, the receipt of neoadjuvant chemotherapy, and prone position remained significant on multivariate analysis (p < 0.05 for all). Prone position vs. supine, higher BMI, the receipt of neoadjuvant chemotherapy, the presence of hypertension, and race (Black people vs. White people) were associated with larger mean lumpectomy cavity volume.

Discussion

These data may be used to select patients for which longer time to simulation may result in smaller lumpectomy cavity volumes and therefore smaller PBI target volumes. Racial disparity in cavity size is not explained by known confounders and may reflect unmeasured systemic determinants of health. Larger datasets and prospective evaluation would be ideal to confirm these hypotheses.

Prediction of pathologic complete response after single-dose MR-guided partial breast irradiation in low-risk breast cancer patients: the ABLATIVE-2 trial-a study protocol

BACKGROUND

Partial breast irradiation (PBI) is standard of care in low-risk breast cancer patients after breast-conserving surgery (BCS). Pre-operative PBI can result in tumor downstaging and more precise target definition possibly resulting in less treatment-related toxicity. This study aims to assess the pathologic complete response (pCR) rate one year after MR-guided single-dose pre-operative PBI in low-risk breast cancer patients.

METHODS

The ABLATIVE-2 trial is a multicenter prospective single-arm trial using single-dose ablative PBI in low-risk breast cancer patients. Patients ≥ 50 years with non-lobular invasive breast cancer ≤ 2 cm, grade 1 or 2, estrogen receptor-positive, HER2-negative, and tumor-negative sentinel node procedure are eligible. A total of 100 patients will be enrolled. PBI treatment planning will be performed using a radiotherapy planning CT and -MRI in treatment position. The treatment delivery will take place on a conventional or MR-guided linear accelerator. The prescribed radiotherapy dose is a single dose of 20 Gy to the tumor, and 15 Gy to the 2 cm of breast tissue surrounding the tumor. Follow-up MRIs, scheduled at baseline, 2 weeks, 3, 6, 9, and 12 months after PBI, are combined with liquid biopsies to identify biomarkers for pCR prediction. BCS will be performed 12 months after radiotherapy or after 6 months, if MRI does not show a radiologic complete response. The primary endpoint is the pCR rate after PBI. Secondary endpoints are radiologic response, toxicity, quality of life, cosmetic outcome, patient distress, oncological outcomes, and the evaluation of biomarkers in liquid biopsies and tumor tissue. Patients will be followed up to 10 years after radiation therapy.

DISCUSSION

This trial will investigate the pathological tumor response after pre-operative single-dose PBI after 12 months in patients with low-risk breast cancer. In comparison with previous trial outcomes, a longer interval between PBI and BCS of 12 months is expected to increase the pCR rate of 42% after 6-8 months. In addition, response monitoring using MRI and biomarkers will help to predict pCR. Accurate pCR prediction will allow omission of surgery in future patients.

TRIAL REGISTRATION

The trial was registered prospectively on April 28th 2022 at clinicaltrials.gov (NCT05350722).

REFINE-Lung implements a novel multi-arm randomised trial design to address possible immunotherapy overtreatment

Increasing evidence suggests that some immunotherapy dosing regimens for patients with advanced cancer could result in overtreatment. Given the high costs of these agents, and important implications for quality of life and toxicity, new approaches are needed to identify and reduce unnecessary treatment. Conventional two-arm non-inferiority designs are inefficient in this context because they require large numbers of patients to explore a single alternative to the standard of care. Here, we discuss the potential problem of overtreatment with anti-PD-1 directed agents in general and introduce REFINE-Lung (NCT05085028), a UK multicentre phase 3 study of reduced frequency pembrolizumab in advanced non-small-cell lung cancer. REFINE-Lung uses a novel multi-arm multi-stage response over continuous interventions (MAMS-ROCI) design to determine the optimal dose frequency of pembrolizumab. Along with a similarly designed basket study of patients with renal cancer and melanoma, REFINE-Lung and the MAMS-ROCI design could contribute to practice-changing advances in patient care and form a template for future immunotherapy optimisation studies across cancer types and indications. This new trial design is applicable to many new or existing agents for which optimisation of dose, frequency, or duration of therapy is desirable.

Special issue. De-escalation of loco-regional treatment in breast cancer: Time to find the balance? Partial breast irradiation

Breast cancer is the most common cancer in women worldwide. Over the past few decades, remarkable progress has been made in understanding the biology and pathology of breast cancer. A personalized conservative approach has been currently adopted addressing the patient's individual risk of relapse. After postoperative whole breast irradiation for early-stage breast cancer, a rate of recurrences outside the initial tumour bed lower than 4% was observed. Thus, the highest benefits of breast irradiation seem to result from the dose delivered to the tissue neighbouring the tumour bed. Nonetheless, reducing treatment morbidity while maintaining radiation therapy's ability to decrease local recurrences is an important challenge in treating patients with radiation therapy. In this regard, strategies such as partial-breast irradiation have been developed to reduce toxicity without compromising oncologic outcomes. According to the national and international published guidelines, clinical oncologists can refer to specific dose/fractionation schedules and eligible criteria. However, there are still some areas of open questions. Breast cancer represents a multidisciplinary paradigm; it should be considered a heterogeneous disease where a "one-treatment-fits-all" approach cannot be considered an appropriate option. This is a wide overview on the main partial breast irradiation advantages, risks, timings, techniques, and available recommendations. We aim to provide practical findings to support clinical decision-making, exploring future perspectives, towards a balance for optimisation of breast cancer.

Hypofractionation: The standard for external beam breast irradiation

This overview provides the historical perspective of external beam breast hypofractionation over the last 50 years. It highlights the serious harm suffered by patients with breast cancer in the 1970's and 1980's because of new hypofractionation regimens based on a theoretical radiobiology model being adopted into clinical practice to solve a resource issue without testing within clinical trials and without the essential radiotherapy quality assurance. It then describes the high-quality clinical trials comparing 3-week with 5-week standard of care regimens that were initiated based on a strong scientific rationale for hypofractionation in breast cancer. Today, there are still challenges with universal implementation of the results of these moderate hypofractionation studies, but there is now a substantial body of evidence to support 3-week breast radiotherapy with several large randomised trials still to report. The limit of breast hypofractionation is then explored and randomised trials investigating 1-week radiotherapy are described. This approach is now standard of care in many countries for whole or partial breast radiotherapy and chest wall radiotherapy without immediate reconstruction. It also has the advantage of reducing burden of treatment for patients and providing cost-effective care. Further research is needed to establish the safety and efficacy of 1-week breast locoregional radiotherapy and following immediate breast reconstruction. In addition, clinical studies are required to determine how a tumour bed boost for patients with breast cancer at higher risk of relapse can be incorporated simultaneously into a 1-week radiotherapy schedule. As such, the breast hypofractionation story is still unfolding.

Deep inspiration breath-hold radiation therapy in left-sided breast cancer patients: a single-institution retrospective dosimetric analysis of organs at risk doses

BACKGROUND

Radiotherapy can induce cardiac injury in left-sided breast cancer cases. Cardiac-sparing irradiation using the deep inspiration breath-hold (DIBH) technique can achieve substantial dose reduction to vulnerable cardiac substructures compared with free breathing (FB). This study evaluated the dosimetric differences between both techniques at a single institution.

METHODS

From 2017 to 2019, 130 patients with left-sided breast cancer underwent breast-conserving surgery (BCS; n = 121, 93.1%) or mastectomy (ME; n = 9, 6.9%) along with axillary lymph node staging (n = 105, 80.8%), followed by adjuvant irradiation in DIBH technique; adjuvant systemic therapy was included if applicable. 106 (81.5%) patients received conventional and 24 (18.5%) hypofractionated irradiation. Additionally, 12 patients received regional nodal irradiation. Computed tomography (CT) scans in FB and DIBH position were performed for all patients. Intrafractional 3D position monitoring of the patient surface in deep inspiration and breath gating was performed using Sentinel and Catalyst HD 3D surface scanning systems (C-RAD, Catalyst, C‑RAD AB, Uppsala, Sweden). Individual coaching and determination of breathing amplitude during the radiation planning CT was performed. Three-dimensional treatment planning was performed using standard tangential treatment portals (6 or 18 MV). The delineation of cardiac structures and both lungs was done in both the FB and the DIBH scan.

RESULTS

All dosimetric parameters for cardiac structures were significantly reduced (p < 0.01 for all). The mean heart dose (Dmean) in the DIBH group was 1.3 Gy (range 0.5-3.6) vs. 2.2 Gy (range 0.9-8.8) in the FB group (p < 0.001). The Dmean for the left ventricle (LV) in DIBH was 1.5 Gy (range 0.6-4.5), as compared to 2.8 Gy (1.1-9.5) with FB (p < 0.001). The parameters for LV (V10 Gy, V15 Gy, V20 Gy, V23 Gy, V25 Gy, V30 Gy) were reduced by about 100% (p < 0.001). The LAD Dmean in the DIBH group was 4.1 Gy (range 1.2-33.3) and 14.3 Gy (range 2.4-37.5) in the FB group (p < 0.001). The median values for LAD such as V15 Gy, V20 Gy, V25 Gy, V30 Gy, and V40 Gy decreased by roughly 100% (p < 0.001). An increasing volume of left lung in the DIBH position resulted in dose sparing of cardiac structures.

CONCLUSION

For all ascertained dosimetric parameters, a significant dose reduction could be achieved in DIBH technique.

Intraoperative Radiation Therapy: A Large Integrated Health Care System's Approach and Outcomes

Introduction Intraoperative radiation therapy (IORT) may not be as effective in the community compared with clinical trials. Methods The authors reviewed data from the electronic health records of patients who received IORT between February 2014 and February 2020 at a single center within a large integrated health care system. The primary outcome was ipsilateral breast tumor recurrence. Results Of 5731 potentially eligible patients, 245 (4.3%) underwent IORT (mean age: 65.4 ± 0.4 years; median follow-up time: 3.5 years ± 2.2 months). According to the American Society for Radiation Oncology's accelerated partial breast irradiation guidelines based on final pathology, 51% of patients were suitable candidates for IORT, 38.4% were cautionary, and 10.6% were unsuitable. For adjuvant therapy, 6.5% had consolidative whole breast irradiation, and 66.4% received endocrine treatment. At the median follow-up time of 3.5 years, overall ipsilateral breast tumor recurrence was 3.7%. Recurrences tended to be more frequent in patients who refused or did not complete endocrine treatment than in those who received it (7.4% vs 1.9%, p = 0.07). The complication rate was 14.7%, with seroma being the most common (8.2%). Discussion The IORT ipsilateral breast tumor recurrence rate of 3.7% confirms a higher-than-expected rate compared to randomized clinical trials, possibly due to less compliance with endocrine therapy. Conclusion The authors subsequently revised their IORT protocol to require endocrine treatment as a part of the IORT treatment plan and to strongly recommend adjuvant whole breast irradiation for all patients deemed cautionary or unsuitable for IORT according to the American Society for Radiation Oncology's accelerated partial breast irradiation guidelines.

De-ESCAlating RadioTherapy in breast cancer patients with pathologic complete response to neoadjuvant systemic therapy: DESCARTES study

PURPOSE

Neoadjuvant systemic therapy (NST) is increasingly used in breast cancer patients and depending on subtype, 10-89% of patients will attain pathologic complete response (pCR). In patients with pCR, risk of local recurrence (LR) after breast conserving therapy is low. Although adjuvant radiotherapy after breast conserving surgery (BCS) reduces LR further in these patients, it may not contribute to overall survival. However, radiotherapy may cause early and late toxicity. The aim of this study is to show that omission of adjuvant radiotherapy in patients with a pCR after NST will result in acceptable low LR rates and good quality of life.

METHODS

The DESCARTES study is a prospective, multicenter, single arm study. Radiotherapy will be omitted in cT1-2N0 patients (all subtypes) who achieve a pCR of the breast and lymph nodes after NST followed by BCS plus sentinel node procedure. A pCR is defined as ypT0N0 (i.e. no residual tumor cells detected). Primary endpoint is the 5-year LR rate, which is expected to be 4% and deemed acceptable if less than 6%. In total, 595 patients are needed to achieve a power of 80% (one-side alpha of 0.05). Secondary outcomes include quality of life, Cancer Worry Scale, disease specific and overall survival. Projected accrual is five years.

CONCLUSION

This study bridges the knowledge gap regarding LR rates when adjuvant radiotherapy is omitted in cT1-2N0 patients achieving pCR after NST. If the results are positive, radiotherapy may be safely omitted in selected breast cancer patients with a pCR after NST.

TRIAL REGISTRATION

This study is registered at ClinicalTrials.gov on June 13th 2022 (NCT05416164). Protocol version 5.1 (15-03-2022).

Implementation of automated personalised breast radiotherapy planning techniques with scripting in Raystation

OBJECTIVE

Implement scripted automatic breast planning (AP) for breast techniques within Raystation.

METHODS

Manual plans (MPs) were re-planned and compared with AP plans for whole breast (WB), partial breast (PB), hybrid volumetric modulated arc therapy simultaneous integrated boost (VMAT SIB) and VMAT nodal plans.

RESULTS

WB AP plans took 7 min comparing well to MP. One WB AP failed a mandatory dose constraint. Small statistically significant differences showed improved coverage for AP at expense of slightly hotter plans, however absolute differences were small (mean differences < 1% or D _0.5cc<0.2 Gy). PB AP plans took 9 min, showing improved coverage (V _24.7Gy97.6 vs 96.4 %). One PB AP case failed a mandatory constraint. Other dosimetric differences were non-significant. SIB AP plans took 14 min with one case failing a mandatory constraint with minor differences compared with MP except larger V _42.8Gy (3 vs 1.5 %) and more MU. VMAT AP plans took 12 min and were hotter for PTVp_4000 but had higher nodal coverage. Contra_Lung V _2.5Gy was higher (8.8 %) than MP plans (6.5 %).

CONCLUSION

Automatic planning of modern breast techniques has been successfully introduced using a commercial planning system. AP plans are very similar to MP, requiring little manual interaction for most cases with significant timesaving potential.

ADVANCES IN KNOWLEDGE

Scripted breast plans produced within minutes for WB, PB, SIB and VMAT. Successfully introduced into large busy department. Plans similar to manual plans, requiring little manual interaction.

Accelerated partial breast irradiation using sole interstitial multicatheter brachytherapy compared with whole-breast irradiation with boost for early breast cancer: 10-year results of a GEC-ESTRO randomised, phase 3, non-inferiority trial

BACKGROUND

Several randomised, phase 3 trials have investigated the value of different techniques of accelerated partial breast irradiation (APBI) for patients with early breast cancer after breast-conserving surgery compared with whole-breast irradiation. In a phase 3 randomised trial, we evaluated whether APBI using multicatheter brachytherapy is non-inferior compared with whole-breast irradiation. Here, we present the 10-year follow-up results.

METHODS

We did a randomised, phase 3, non-inferiority trial at 16 hospitals and medical centres in Austria, Czech Republic, Germany, Hungary, Poland, Spain, and Switzerland. Patients aged 40 years or older with early invasive breast cancer or ductal carcinoma in situ treated with breast-conserving surgery were centrally randomly assigned (1:1) to receive either whole-breast irradiation or APBI using multicatheter brachytherapy. Whole-breast irradiation was delivered in 25 daily fractions of 50 Gy over 5 weeks, with a supplemental boost of 10 Gy to the tumour bed, and APBI was delivered as 30·1 Gy (seven fractions) and 32·0 Gy (eight fractions) of high-dose-rate brachytherapy in 5 days or as 50 Gy of pulsed-dose-rate brachytherapy over 5 treatment days. Neither patients nor investigators were masked to treatment allocation. The primary endpoint was ipsilateral local recurrence, analysed in the as-treated population; the non-inferiority margin for the recurrence rate difference (defined for 5-year results) was 3 percentage points. The trial is registered with ClinicalTrials.gov, NCT00402519; the trial is complete.

FINDINGS

Between April 20, 2004, and July 30, 2009, 1328 female patients were randomly assigned to whole breast irradiation (n=673) or APBI (n=655), of whom 551 in the whole-breast irradiation group and 633 in the APBI group were eligible for analysis. At a median follow-up of 10·36 years (IQR 9·12-11·28), the 10-year local recurrence rates were 1·58% (95% CI 0·37 to 2·8) in the whole-breast irradiation group and 3·51% (1·99 to 5·03) in the APBI group. The difference in 10-year rates between the groups was 1·93% (95% CI -0·018 to 3·87; p=0·074). Adverse events were mostly grade 1 and 2, in 234 (60%) of 393 participants in the whole-breast irradiation group and 314 (67%) of 470 participants in the APBI group, at 7·5-year or 10-year follow-up, or both. Patients in the APBI group had a significantly lower incidence of treatment-related grade 3 late side-effects than those in the whole-breast irradiation group (17 [4%] of 393 for whole-breast irradiation vs seven [1%] of 470 for APBI; p=0·021; at 7·5-year or 10-year follow-up, or both). At 10 years, the most common type of grade 3 adverse event in both treatment groups was fibrosis (six [2%] of 313 patients for whole-breast irradiation and three [1%] of 375 patients for APBI, p=0·56). No grade 4 adverse events or treatment-related deaths have been observed.

INTERPRETATION

Postoperative APBI using multicatheter brachytherapy after breast-conserving surgery in patients with early breast cancer is a valuable alternative to whole-breast irradiation in terms of treatment efficacy and is associated with fewer late side-effects.

FUNDING

German Cancer Aid, Germany.

Optimising post-operative radiation therapy after oncoplastic and reconstructive procedures

Surgical techniques for breast cancer have been refined over the past decades to deliver an aesthetic outcome as close as possible to the contralateral intact breast. Current surgery further allows excellent aesthetic outcome even in case of mastectomy, by performing skin sparing or nipple sparing mastectomy in combination with breast reconstruction. In this review we discuss how to optimise post-operative radiation therapy after oncoplastic and breast reconstructive procedures, including dose, fractionation, volumes, surgical margins, and boost application.

Optimizing Preventive Adjuvant Linac-Based (OPAL) Radiation: A Phase 2 Trial of Daily Partial Breast Irradiation

PURPOSE

Evidence supports use of partial-breast irradiation (PBI) in the management of early breast cancer, but the optimal dose-fractionation remains unsettled.

METHODS AND MATERIALS

We conducted a phase 2 clinical trial (OPAL trial) to evaluate a novel PBI dosing schedule of 35 Gy in 10 daily fractions. Patients with close (<2 mm) margins also received a boost of 9 Gy in 3 fractions. Eligible patients underwent margin-negative lumpectomy for ductal carcinoma in situ or estrogen receptor-positive invasive breast cancer, up to 3 cm, pTis-T2 N0. The primary outcome was any grade ≥2 toxic effect occurring from the start of radiation through 6 months of follow-up. Secondary outcomes included patient-reported cosmesis, breast pain, and functional status, measured using the Breast Cancer Treatment Outcomes Scale, and physician-reported cosmesis, measured using the Radiation Therapy and Oncology Group scale. The Cochran-Armitage trend test and multivariable mixed-effects longitudinal growth curve models compared outcomes for the OPAL study population with those for a control group of similar patients treated with whole-breast irradiation (WBI) plus boost.

RESULTS

All 149 patients enrolled on the OPAL trial received the prescribed dose, and 17.4% received boost. The median age was 64 years; 83.2% were White, and 73.8% were overweight or obese. With median follow-up of 2.0 years, 1 patient (0.7%) experienced in-breast recurrence. Prevalence of the primary toxicity outcome was 17.4% (26 of 149 patients) in the OPAL trial compared with 72.7% (128 of 176 patients) in the control WBI-plus-boost cohort (P < .001). In longitudinal multivariable analysis, treatment on the OPAL trial was associated with improved patient-reported cosmesis (P < .001), functional status (P = .004), breast pain (P = .004), and physician-reported cosmesis (P < .001).

CONCLUSIONS

Treatment with daily PBI was associated with substantial reduction in early toxicity and improved patient- and physician-reported outcomes compared with WBI plus boost. Daily external-beam partial-breast irradiation with 13 or fewer fractions merits further prospective evaluation.

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.

Early effectiveness and toxicity outcomes of reirradiation after breast conserving surgery for recurrent or new primary breast cancer

PURPOSE

Breast reirradiation (reRT) after breast conserving surgery (BCS) has emerged as a viable alternative to mastectomy for women presenting with recurrent or new primary breast cancer. There are limited data on safety of different fractionation regimens. This study reports safety and efficacy among women treated with repeat BCS and reRT.

METHODS AND MATERIALS

Patients who underwent repeat BCS followed by RT from 2015 to 2021 at 2 institutions were analyzed. Univariate logistic regression models were used to identify predictors of acute and late toxicities. Kaplan-Meier estimates were used to evaluate overall survival (OS), distant metastasis-free survival (DMFS) and locoregional recurrence-free survival (LR-RFS).

RESULTS

Sixty-six patients were reviewed with median follow-up of 16 months (range: 3-60 months). At time of first recurrence, 41% had invasive carcinoma with a ductal carcinoma in situ (DCIS) component, 41% had invasive carcinoma alone and 18% had DCIS alone. All were clinically node negative. For the reirradiation course, 95% received partial breast irradiation (PBI) (57.5% with 1.5 Gy BID; 27% with 1.8 Gy daily; 10.5% with hypofractionation), and 5% received whole breast irradiation (1.8-2 Gy/fx), all of whom had received PBI for initial course. One patient experienced grade 3 fibrosis, and one patient experienced grade 3 telangiectasia. None had grade 4 or higher late adverse events. We found no association between the fractionation of the second course of RT or the cumulative dose (measured as EQD2) with acute or late toxicity. At 2 years, OS was 100%, DMFS was 91.6%, and LR-RFS was 100%.

CONCLUSION

In this series of patients with recurrent or new primary breast cancer, a second breast conservation surgery followed by reirradiation was effective with no local recurrences and an acceptable toxicity profile across a range of available fractionation regimens at a median follow up of 16 months. Longer follow up is required.

Different Re-Irradiation Techniques after Breast-Conserving Surgery for Recurrent or New Primary Breast Cancer

Breast re-irradiation (reRT) after breast-conserving surgery (BCS) using external beam radiation is an increasingly used salvage approach for women presenting with recurrent or new primary breast cancer. However, radiation technique, dose and fractionation as well as eligibility criteria differ between studies. There is also limited data on efficacy and safety of external beam hypofractionation and accelerated partial-breast irradiation (APBI) regimens. This paper reviews existing retrospective and prospective data for breast reRT after BCS, APBI reRT outcomes and delivery at our institution and the need for a randomized controlled trial using shorter courses of radiation to better define patient selection for different reRT fractionation regimens.

Cosmetic Results and Side Effects of Accelerated Partial-Breast Irradiation Versus Whole-Breast Irradiation for Low-Risk Invasive Carcinoma of the Breast: The Randomized Phase III IRMA Trial

PURPOSE

The results in terms of side effects vary among the published accelerated partial-breast irradiation (APBI) studies. Here, we report the 5-year results for cosmetic outcomes and toxicity of the IRMA trial.

METHODS

We ran this randomized phase III trial in 35 centers. Women with stage I-IIA breast cancer treated with breast-conserving surgery, age ≥ 49 years, were randomly assigned 1:1 to receive either whole-breast irradiation (WBI) or external beam radiation therapy APBI (38.5 Gy/10 fraction twice daily). Patients and investigators were not masked to treatment allocation. The primary end point was ipsilateral breast tumor recurrence. We hereby present the analysis of the secondary outcomes, cosmesis, and normal tissue toxicity. All side effects were graded with the Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer Radiation Morbidity Scoring Schema. Analysis was performed with both intention-to-treat and as-treated approaches.

RESULTS

Between March 2007 and March 2019, 3,309 patients were randomly assigned to 1,657 WBI and 1,652 APBI; 3,225 patients comprised the intention-to-treat population (1,623 WBI and 1,602 APBI). At a median follow-up of 5.6 (interquartile range, 4.0-8.4) years, adverse cosmesis in the APBI patients was higher than that in the WBI patients at 3 years (12.7% v 9.2%; P = .009) and at 5 years (14% v 9.8%; P = .012). Late soft tissue toxicity (grade ≥ 3: 2.8% APBI v 1% WBI, P < .0001) and late bone toxicity (grade ≥ 3: 1.1% APBI v 0% WBI, P < .0001) were significantly higher in the APBI arm. There were no significant differences in late skin and lung toxicities.

CONCLUSION

External beam radiation therapy-APBI with a twice-daily IRMA schedule was associated with increased rates of late moderate soft tissue and bone toxicities, with a slight decrease in patient-reported cosmetic outcomes at 5 years when compared with WBI, although overall toxicity was in an acceptable range.

Pilot/Phase II Trial of Hypofractionated Radiation Therapy to the Whole Breast Alone Before Breast Conserving Surgery

Purpose

Our purpose was to report the results of a phase II trial of patients with breast cancer treated with hypofractionated whole breast radiation therapy (RT) before breast-conserving surgery (BCS).

Methods and materials

Between 2019 and 2020, patients with cT0-T2, N0, M0 breast cancer were enrolled. Patients were treated with hypofractionated whole breast RT, 25 Gy in 5 fractions, 4 to 8 weeks before BCS. Pathologic assessment was performed using the residual cancer burden (RCB). Toxicities were assessed according to Common Terminology Criteria for Adverse Events (version 4). Quality of life was assessed with Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events, The Breast Cancer Treatment Outcome Scale, Linear Analogue Self-Assessment, and Patient-Reported Outcomes Measurement Information System.

Results

Twenty-two patients were enrolled. Median follow-up was 7.6 months (range, 0.2-16.8). Seven (32%) and 2 (9%) patients experienced grade 2+ or 3 toxicities, respectively. Overall quality of life Linear Analogue Self-Assessment and Patient-Reported Outcomes Measurement Information System did not change significantly from baseline (P = .21 and P = .72, respectively). There was no clinically significant change (≥1 point) in any of The Breast Cancer Treatment Outcome Scale domains. Only 1 (5%) patient experienced a clinical deterioration that corresponded to a "fair" outcome on the Harvard Cosmesis Scale. At pathologic evaluation, 14 (64%) patients had RCB-0 or RCB-I, including 3 (14%) patients with a pathologic complete response (RCB-0). Eight patients (36%) had RCB-II. No local or distant recurrences have been observed.

Conclusions

Extremely hypofractionated whole breast RT before BCS is a feasible approach. There were low rates of toxicities and good cosmesis. Further investigation into this approach with RT before BCS is warranted.

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.

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

Several phase 3 trials have demonstrated partial breast irradiation noninferiority compared with whole breast irradiation in terms of local control and similar or reduced toxicity. During recent years, especially owing to the COVID-19 pandemic, a growing interest in 5-fraction regimens emerged. The APBI-IMRT-Florence trial (NCT02104895) schedule (30 Gy in 5 fractions) might represent an appealing treatment option, being both a safe and effective partial breast irradiation schedule, with long-term reported results. The aim of this report is to support planners interested in implementing this technique and to warrant equal access to postoperative radiation treatment for most early breast cancer patient candidates. We report the current delivery technique optimized from the original protocol and the updated dose constraints for plan optimization. We also report a statistical analysis of dosimetric parameters on 50 patients treated in consecutive fractions. Treatment-related toxic effects were assessed using the acute radiation morbidity scoring criteria and late radiation morbidity scoring scheme from the Radiation Therapy Oncology Group and the European Organisation for Research and Treatment of Cancer. The mean volume of ipsilateral breast was 731 cm³ (standard deviation ± 450; range, 151-2205) and the mean planning target volume (PTV) was 139 cm³ (standard deviation ± 48; range, 55-259). There was good correlation between ipsilateral breast V_15Gy and the ratio between the PTV and ipsilateral breast volume (R² = .911). At a median follow-up of 4.5 years, 32% of patients (n = 16) developed any grade 1 acute toxic effect. No grade >1 toxic effect was observed. Sixteen percent of patients (n = 8) developed any grade 1 late toxic effect. No grade >1 toxic effect was observed. Physician-assessed cosmesis was reported as excellent (84%), good (14%), and fair (2%). The schedule of 30 Gy in 5 consecutive fractions might represent a safe, easy-to-deliver, and cost-effective option for appropriately selected patients affected by early breast cancer.

Effect of standardised surgical assessment and shared decision-making on morbidity and patient satisfaction after breast conserving therapy: A cross-sectional study

BACKGROUND

The role of oncoplastic breast conserving therapy (OPBCT) on physical function, morbidity and patient satisfaction has yet to be defined. Additionally, technique selection should be individualised and incorporate patient preference. The study aim was to investigate differences between "standard" (sBCT) and oncoplastic breast conservation (OPBCT) in patient-reported outcomes (PROs) when patients have been assessed in a standardised manner and technique selection has been reached through shared decision-making (SDM).

METHODS

This is a cross-sectional study of 215 women treated at a tertiary referral centre. Standardised surgical assessment included breast and lesion volumetry, definition of resection ratio, patient-related risk factors and patient preference. Postoperative morbidity and patient satisfaction were assessed by validated PROs tools (Diseases of the Arm, Shoulder and Hand-DASH and Breast-Q). Patient experience was assessed by semi-structured interviews.

RESULTS

There was no difference of the median values between OPBCT and sBCT in postoperative morbidity of the upper extremity (DASH 3.3 vs 5, p = 0.656) or the function of the chest wall (Breast-Q 82 vs 82, p = 0.758). Postoperative satisfaction with breasts did not differ either (Breast-Q 65 vs 61, p = 0.702). On the individual level, women that opted for OPBCT after SDM had improved satisfaction when compared to baseline (+3 vs -1, p = 0.001). Shared decision-making changed patient attitude in 69.8% of patients, leading most often to de-escalation from mastectomy.

CONCLUSIONS

These findings support that a combination of standardised surgical assessment and SDM allows for tailored treatment and de-escalation of oncoplastic surgery without negatively affecting patient satisfaction and morbidity.

An Update to the Malthus Model for Radiotherapy Utilisation in England

AIMS

The Malthus Programme predicts national and local radiotherapy demand by combining cancer incidence data with decision trees detailing the indications, and appropriate dose fractionation, for radiotherapy. Since the last model update in 2017, technological advancements and the COVID-19 pandemic have led to increasing hypofractionation of radiotherapy schedules. Indications for radiotherapy have also evolved, particularly in the context of oligometastatic disease. Here we present a brief update on the model for 2021. We have updated the decision trees for breast, prostate, lung and head and neck cancers, and incorporated recent cancer incidence data into our model, generating a current estimate of fraction demand for these four cancer sites across England.

MATERIALS AND METHODS

The decision tree update was based on evidence from practice-changing randomised controlled trials, published guidelines, audit data and expert opinion. Site- and stage-specific incidence data were taken from the National Disease Registration Service. We used the updated model to estimate the proportion of patients who would receive radiotherapy (appropriate rate of radiotherapy) and the fraction demand per million population at a national and Clinical Commissioning Group level in 2021.

RESULTS

The total predicted fraction demand has decreased by 11.4% across all four cancer sites in our new model, compared with the 2017 version. This reduction can be explained primarily by greater use of hypofractionated treatments (including stereotactic ablative radiotherapy) and a shift towards earlier stage presentation. The only large change in appropriate rate of radiotherapy was an absolute decrease of 3% for lung cancer.

CONCLUSIONS

Compared with our previous model, the current version predicts a reduction in fraction demand across England. This is driven principally by hypofractionation of radiotherapy regimens, using technology that requires increasingly complex planning. Treatment complexity and local service factors need to be taken into account when translating fraction burden into linear accelerator demand or throughput.

Prospective imaging comparison of anatomic delineation with rapid kV cone beam CT on a novel ring gantry radiotherapy device

INTRODUCTION

A kV imager coupled to a novel, ring-gantry radiotherapy system offers improved on-board kV-cone-beam computed tomography (CBCT) acquisition time (17-40 seconds) and image quality, which may improve CT radiotherapy image-guidance and enable online adaptive radiotherapy. We evaluated whether inter-observer contour variability over various anatomic structures was non-inferior using a novel ring gantry kV-CBCT (RG-CBCT) imager as compared to diagnostic-quality simulation CT (simCT).

MATERIALS/METHODS

Seven patients undergoing radiotherapy were imaged with the RG-CBCT system at breath hold (BH) and/or free breathing (FB) for various disease sites on a prospective imaging study. Anatomy was independently contoured by seven radiation oncologists on: 1. SimCT 2. Standard C-arm kV-CBCT (CA-CBCT), and 3. Novel RG-CBCT at FB and BH. Inter-observer contour variability was evaluated by computing simultaneous truth and performance level estimation (STAPLE) consensus contours, then computing average symmetric surface distance (ASSD) and Dice similarity coefficient (DSC) between individual raters and consensus contours for comparison across image types.

RESULTS

Across 7 patients, 18 organs-at-risk (OARs) were evaluated on 27 image sets. Both BH and FB RG-CBCT were non-inferior to simCT for inter-observer delineation variability across all OARs and patients by ASSD analysis (p < 0.001), whereas CA-CBCT was not (p = 0.923). RG-CBCT (FB and BH) also remained non-inferior for abdomen and breast subsites compared to simCT on ASSD analysis (p < 0.025). On DSC comparison, neither RG-CBCT nor CA-CBCT were non-inferior to simCT for all sites (p > 0.025).

CONCLUSIONS

Inter-observer ability to delineate OARs using novel RG-CBCT images was non-inferior to simCT by the ASSD criterion but not DSC criterion.

Accelerated Partial Breast Irradiation: An Opportunity for Therapeutic De-escalation

Partial breast irradiation (PBI) has been demonstrated to have comparable outcomes to whole breast irradiation based on multiple randomized trials with long-term follow-up. However, despite the strength of the data available, PBI remains underutilized despite being an appropriate option for many women diagnosed with early-stage breast cancer. This is significant, as PBI offers the potential to reduce toxicities and shorten treatment duration without impacting outcomes; in addition, for low-risk patients, PBI alone is being investigated as an alternative to endocrine therapy alone. Modern PBI can be delivered with multiple techniques, and advances in treatment planning have allowed for improved therapeutic ratios compared with earlier techniques; one such approach is utilizing stereotactic body radiation therapy approaches allowing for smaller target margins and therefore lower breast doses. Moving forward, studies are ongoing evaluating the use of radiation alone including PBI as compared with endocrine therapy alone, with prospective studies evaluating stereotactic body radiation therapy.

A Meta-Analysis of Trials of Partial Breast Irradiation

PURPOSE

Partial breast irradiation (PBI) is the delivery of radiation therapy (RT) limited to the tumor bed after breast conserving surgery. The results of recent trials of PBI compared with whole breast irradiation (WBI) have suggested conflicting results with respect to local control and toxicity. The purpose of this meta-analysis was to assess effectiveness of PBI and to compare the different techniques.

METHODS AND MATERIALS

A meta-analysis of aggregate data from published randomized trials was performed to examine the effectiveness of PBI compared with WBI in patients with invasive breast cancer and ductal carcinoma in situ. Relevant data were extracted. The primary outcome was any ipsilateral breast event (invasive or noninvasive). Secondary outcomes included acute and late toxicity. The results of randomized trials were pooled using a fixed effects model and the inverse variance method.

RESULTS

Fifteen trials involving 16,474 patients were identified. The majority of enrolled patients were >60 years of age and had T1N0 grade 1 to 2 disease treated with hormone therapy. The percent of ipsilateral breast events was higher in patients treated with PBI compared with WBI (5.0% vs 2.8%; risk ratio [RR], 1.72; 95% confidence interval [CI], 1.47-2.02). Heterogeneity (P = .0002) was observed between the 4 PBI techniques: external beam RT without computed tomography (CT) planning (RR, 2.06; 95% CI, 1.36-3.12); brachytherapy (RR, 1.21; 95% CI, 0.65-2.25); intraoperative RT (RR, 2.79; 95% CI, 2.08-3.73); and external beam RT with CT planning (RR, 1.25; 95% CI, 0.99-1.58). When external beam RT without CT planning and intraoperative RT trials were excluded, the percent of ipsilateral breast events was 3.3% versus 2.6%, respectively (RR, 1.25; 95% CI, 1.00-1.55; P = .05), and no heterogeneity was observed (P = .92). Overall, acute toxicity was less with PBI, and the effect on late toxicity varied by technique.

CONCLUSIONS

Overall, WBI was more effective than PBI, but the effectiveness of PBI was technique related. PBI was less effective when given by external beam RT without CT planning or intraoperative therapy. Although PBI given by multicatheter brachytherapy or external beam RT with CT planning tended to be statistically less effective than WBI, the absolute difference between groups for ipsilateral breast events was very small (<1%), supporting these approaches for women considering PBI.

Cost-effectiveness of 5 fraction and partial breast radiotherapy for early breast cancer in the UK: model-based multi-trial analysis

PURPOSE

We estimated the cost-effectiveness of 4 radiotherapy modalities to treat early breast cancer in the UK. In a subgroup of patients eligible for all modalities, we compared whole-breast (WB) and partial breast (PB) radiotherapy delivered in either 15 (WB15F, PB15F) or 5 fractions (WB5F, PB5F). In a subgroup ineligible for PB radiotherapy, we compared WB15F to WB5F.

METHODS

We developed a Markov cohort model to simulate lifetime healthcare costs and quality-adjusted life years (QALYs) for each modality. This was informed by the clinical analysis of two non-inferiority trials (FAST Forward and IMPORT LOW) and supplemented with external literature. The primary analysis assumed that radiotherapy modality influences health only through its impact on locoregional recurrence and radiotherapy-related adverse events.

RESULTS

In the primary analysis, PB5F had the least cost and greatest expected QALYs. WB5F had the least cost and the greatest expected QALYs in those only eligible for WB radiotherapy. Applying a cost-effectiveness threshold of £15,000/QALY, there was a 62% chance that PB5F was the cost-effective alternative in the PB eligible group, and there was a 100% chance that WB5F was cost-effective in the subgroup ineligible for PB radiotherapy.

CONCLUSIONS

Hypofractionation to 5 fractions and partial breast radiotherapy modalities offer potentially important benefits to the UK health system.

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.

The Prognostic and Predictive Value of Genomic Assays in Guiding Adjuvant Breast Radiation Therapy

Many patients with non-metastatic breast cancer benefit from adjuvant radiation therapy after lumpectomy or mastectomy on the basis of many randomized trials. However, there are many patients that have such low risks of recurrence after surgery that de-intensification of therapy by either reducing the treatment volume or omitting radiation altogether may be appropriate options. On the other hand, dose intensification may be necessary for more aggressive breast cancers. Until recently, these treatment decisions were based solely on clinicopathologic factors. Here, we review the current literature on the role of genomic assays as prognostic and/or predictive biomarkers to help guide adjuvant radiation therapy decision-making.

Optimizing Adjuvant Treatment Recommendations for Older Women with Biologically Favorable Breast Cancer: Short-Course Radiation or Long-Course Endocrine Therapy?

Omission of radiotherapy among older women taking 5 years of adjuvant endocrine therapy following breast conserving surgery for early-stage, hormone sensitive breast cancers is well-studied. However, endocrine therapy toxicities are significant, and many women have difficulty tolerating endocrine therapy, particularly elderly patients with comorbidities. Omission of endocrine therapy among women receiving adjuvant radiation is less well-studied, but available randomized and non-randomized data suggest that this approach may confer equivalent local control and survival for select patients. Herein we review available randomized and non-randomized outcome data for women treated with radiation monotherapy and emphasize the need for future prospective, randomized studies of endocrine therapy omission.

Radiation in Early-Stage Breast Cancer: Moving beyond an All or Nothing Approach

Radiotherapy omission is increasingly considered for selected patients with early-stage breast cancer. However, with emerging data on the safety and efficacy of radiotherapy de-escalation with partial breast irradiation and accelerated treatment regimens for low-risk breast cancer, it is necessary to move beyond an all-or-nothing approach. Here, we review existing data for radiotherapy omission, including the use of age, tumor subtype, and multigene profiling assays for selecting low-risk patients for whom omission is a reasonable strategy. We review data for de-escalated radiotherapy, including partial breast irradiation and acceleration of treatment time, emphasizing these regimens' decreasing biological and financial toxicities. Lastly, we review evidence of omission of endocrine therapy. We emphasize ongoing research to define patient selection, treatment delivery, and toxicity outcomes for de-escalated adjuvant therapies better and highlight future directions.

Partial Breast Irradiation Versus Whole Breast Irradiation for Early Breast Cancer Patients in a Randomized Phase III Trial: The Danish Breast Cancer Group Partial Breast Irradiation Trial

PURPOSE

On the basis of low risk of local recurrence in elderly patients with breast cancer after conservative surgery followed by whole breast irradiation (WBI), the Danish Breast Cancer Group initiated the noninferiority external-beam partial breast irradiation (PBI) trial (ClinicalTrials.gov identifier: NCT00892814). We hypothesized that PBI was noninferior to WBI regarding breast induration.

METHODS

Patients operated with breast conservation for relatively low-risk breast cancer were randomly assigned to WBI versus PBI, and all had 40 Gy/15 fractions. The primary end point was 3-year grade 2-3 breast induration.

RESULTS

In total, 865 evaluable patients (434 WBI and 431 PBI) were enrolled between 2009 and 2016. Median follow-up was 5.0 years (morbidity) and 7.6 years (locoregional recurrence). The 3-year rate of induration was 9.7% for WBI and 5.1% for PBI (P = .014). Large breast size was significantly associated with induration with a 3-year incidence of 13% (WBI) and 6% (PBI) for large-breasted patients versus 6% (WBI) and 5% (PBI) for small-breasted patients. PBI showed no increased risk of dyspigmentation, telangiectasia, edema, or pain, and patient satisfaction was high. Letrozole and smoking did not increase the risk of radiation-associated morbidity. Sixteen patients had a locoregional recurrence (six WBI and 10 PBI; P = .28), 20 patients had a contralateral breast cancer, and eight patients had distant failure (five WBI and three PBI). A nonbreast second cancer was detected in 73 patients (8.4%), and there was no difference between groups.

CONCLUSION

External-beam PBI for patients with low-risk breast cancer was noninferior to WBI in terms of breast induration. Large breast size was a risk factor for radiation-associated induration. Few recurrences were detected and unrelated to PBI.