Phase 1 Clinical Trial of Stereotactic Body Radiation Therapy Concomitant With Neoadjuvant Chemotherapy for Breast Cancer

The Role of MRI in Breast Cancer and Breast Conservation Therapy

Contrast-enhanced breast MRI has an established role in aiding in the detection, evaluation, and management of breast cancer. This article discusses MRI sequences, the clinical utility of MRI, and how MRI has been evaluated for use in breast radiotherapy treatment planning. We highlight the contribution of MRI in the decision-making regarding selecting appropriate candidates for breast conservation therapy and review the emerging role of MRI-guided breast radiotherapy.

Radiation enhancement using focussed ultrasound-stimulated microbubbles for breast cancer: A Phase 1 clinical trial

BACKGROUND

Preclinical studies have demonstrated that tumour cell death can be enhanced 10- to 40-fold when radiotherapy is combined with focussed ultrasound-stimulated microbubble (FUS-MB) treatment. The acoustic exposure of microbubbles (intravascular gas microspheres) within the target volume causes bubble cavitation, which induces perturbation of tumour vasculature and activates endothelial cell apoptotic pathways responsible for the ablative effect of stereotactic body radiotherapy. Subsequent irradiation of a microbubble-sensitised tumour causes rapid increased tumour death. The study here presents the mature safety and efficacy outcomes of magnetic resonance (MR)-guided FUS-MB (MRgFUS-MB) treatment, a radioenhancement therapy for breast cancer.

METHODS AND FINDINGS

This prospective, single-center, single-arm Phase 1 clinical trial included patients with stages I-IV breast cancer with in situ tumours for whom breast or chest wall radiotherapy was deemed adequate by a multidisciplinary team (clinicaltrials.gov identifier: NCT04431674). Patients were excluded if they had contraindications for contrast-enhanced MR or microbubble administration. Patients underwent 2 to 3 MRgFUS-MB treatments throughout radiotherapy. An MR-coupled focussed ultrasound device operating at 800 kHz and 570 kPa peak negative pressure was used to sonicate intravenously administrated microbubbles within the MR-guided target volume. The primary outcome was acute toxicity per Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Secondary outcomes were tumour response at 3 months and local control (LC). A total of 21 female patients presenting with 23 primary breast tumours were enrolled and allocated to intervention between August/2020 and November/2022. Three patients subsequently withdrew consent and, therefore, 18 patients with 20 tumours were included in the safety and LC analyses. Two patients died due to progressive metastatic disease before 3 months following treatment completion and were excluded from the tumour response analysis. The prescribed radiation doses were 20 Gy/5 fractions (40%, n = 8/20), 30 to 35 Gy/5 fractions (35%, n = 7/20), 30 to 40 Gy/10 fractions (15%, n = 3/20), and 66 Gy/33 fractions (10%, n = 2/20). The median follow-up was 9 months (range, 0.3 to 29). Radiation dermatitis was the most common acute toxicity (Grade 1 in 16/20, Grade 2 in 1/20, and Grade 3 in 2/20). One patient developed grade 1 allergic reaction possibly related to microbubbles administration. At 3 months, 18 tumours were evaluated for response: 9 exhibited complete response (50%, n = 9/18), 6 partial response (33%, n = 6/18), 2 stable disease (11%, n = 2/18), and 1 progressive disease (6%, n = 1/18). Further follow-up of responses indicated that the 6-, 12-, and 24-month LC rates were 94% (95% confidence interval [CI] [84%, 100%]), 88% (95% CI [75%, 100%]), and 76% (95% CI [54%, 100%]), respectively. The study's limitations include variable tumour sizes and dose fractionation regimens and the anticipated small sample size typical for a Phase 1 clinical trial.

CONCLUSIONS

MRgFUS-MB is an innovative radioenhancement therapy associated with a safe profile, potentially promising responses, and durable LC. These results warrant validation in Phase 2 clinical trials.

TRIAL REGISTRATION

clinicaltrials.gov, identifier NCT04431674.

Treatment Options for Early Stage Inoperable Breast Cancer: Cryoablation or Radiotherapy?

Background

Surgical removal of the tumour is the gold standard treatment for early stage invasive breast cancer. However, with a global ageing population, a larger number of diagnoses are occurring in women with comorbidities that render them unsuitable for surgery. Hence, it is of interest to explore alternative treatment strategies for this group of women.

Summary

Our narrative review aims to explore two such techniques, cryoablation and external beam radiotherapy, providing a brief summary of the evidence behind each technique. Following this, we discuss which groups of patients would gain the most benefit from each technique. Factors favouring the use of radiotherapy include patients with larger tumours, more superficial tumours, and those with less well-demarcated tumours where there is uncertainty regarding tumour extent. Meanwhile, patients who may benefit more from cryoablation include those who desire a smaller number of treatment sessions, have concerns regarding cosmesis and skin pigmentation, or who have relative contraindications to radiotherapy such as scleroderma, systemic lupus erythematosus, reduced lung function, or cardiac comorbidities.

Key Messages

Continued advancements in both cryoablation and radiotherapy technologies are taking place, in tandem with imaging technologies enabling greater certainty in tumour detection and delineation. These factors will help increase local control rates in this group of non-operable early stage breast cancer patients. Through this review, we hope to aid in the clinical decision-making process regarding the selection and referral of patients for each treatment.

Stereotactic body radiation therapy (SBRT) for the treatment of primary breast cancer in patients not undergoing surgery

PURPOSE

The purpose was to explore the role of stereotactic body radiation therapy (SBRT) in providing local control (LC) for primary breast cancer in patients unable to undergo surgery.

MATERIALS/METHODS

Between 2015 and 2019, 13 non-surgical candidates with 14 lesions were treated with SBRT for primary breast cancer. In 4 cases, SBRT was used after whole breast radiation therapy (WBRT; 40-50 Gy/20-25 fractions). SBRT dose was 30-40 ​Gy in 5 fractions for patients treated with SBRT alone and 25-32 ​Gy in 4-5 fractions for those treated with SBRT ​+ ​WBRT. LC and overall survival (OS) were estimated using Kaplan-Meier curves. Response was also assessed using RECIST guidelines.

RESULTS

Median follow-up was 32 (range: 3.4-70.4) months. Imaging at median 2.2 (0.6-8.1) months post-SBRT showed median 43.2 ​% (range: 2-100 ​%) decrease in the largest diameter and median 68.7 ​% (range: 27.9-100 ​%) SUV reduction. There were 3 cases of local progression at 8.7-10.6 months. Estimated LC was 100 ​% at 6 months and 71.6 ​% at 12, 24 and 36 months. Estimated median OS was 100 ​% at 6 months, 76.9 ​% at 12 months, and 61.5 ​% at 24 and 36 months. Acute toxicity (n ​= ​13; 92.9 ​%) included grade (G)1 (n ​= ​8), G2 (n ​= ​4), and G4 (necrosis; n ​= ​1). Late toxicity included G2 edema (n ​= ​1) and G4 necrosis (n ​= ​2, including 1 consequential late effect). Only patients treated with SBRT ​+ ​WBRT experienced acute/late G4 toxicity, managed with resection or steroids.

CONCLUSIONS

SBRT to primary breast cancer resulted in good LC in non-surgical/metastatic patients. Although necrosis (n ​= ​2) occurred in the SBRT ​+ ​WBRT group, it was successfully salvaged.

Effects of neoadjuvant stereotactic body radiotherapy plus adebrelimab and chemotherapy for triple-negative breast cancer: A pilot study

Background

Emerging data have supported the immunostimulatory role of radiotherapy, which could exert a synergistic effect with immune checkpoint inhibitors (ICIs). With proven effective but suboptimal effect of ICI and chemotherapy in triple-negative breast cancer (TNBC), we designed a pilot study to explore the efficacy and safety of neoadjuvant stereotactic body radiotherapy (SBRT) plus adebrelimab and chemotherapy in TNBC patients.

Methods

Treatment-naïve TNBC patients received two cycles of intravenous adebrelimab (20 mg/kg, every 3 weeks), and SBRT (24 Gy/3 f, every other day) started at the second cycle, then followed by six cycles of adebrelimab plus nab-paclitaxel (125 mg/m² on days 1 and 8) and carboplatin (area under the curve 6 mg/mL per min on day 1) every 3 weeks. The surgery was performed within 3-5 weeks after the end of neoadjuvant therapy. Primary endpoint was pathological complete response (pCR, ypT0/is ypN0). Secondary endpoints included objective response rate (ORR), residual cancer burden (RCB) 0-I, and safety.

Results

13 patients were enrolled and received at least one dose of therapy. 10 (76.9%) patients completed SBRT and were included in efficacy analysis. 90% (9/10) of patients achieved pCR, both RCB 0-I and ORR reached 100% with three patients achieved complete remission. Adverse events (AEs) of all-grade and grade 3-4 occurred in 92.3% and 53.8%, respectively. One (7.7%) patient had treatment-related serious AEs. No radiation-related dermatitis or death occurred.

Conclusions

Adding SBRT to adebrelimab and neoadjuvant chemotherapy led to a substantial proportion of pCR with acceptable toxicities, supporting further exploration of this combination in TNBC patients.

Funding

None.

Clinical trial number

NCT05132790.

First-in-human study of SBRT and adenosine pathway blockade to potentiate the benefit of immunochemotherapy in early-stage luminal B breast cancer: results of the safety run-in phase of the Neo-CheckRay trial

BACKGROUND

Luminal B breast cancer (BC) presents a worse prognosis when compared with luminal A BC and exhibits a lower sensitivity to chemotherapy and a lower immunogenicity in contrast to non-luminal BC subtypes. The Neo-CheckRay clinical trial investigates the use of stereotactic body radiation therapy (SBRT) directed to the primary tumor in combination with the adenosine pathway inhibitor oleclumab to improve the response to neo-adjuvant immuno-chemotherapy in luminal B BC. The trial consists of a safety run-in followed by a randomized phase II trial. Here, we present the results of the first-in-human safety run-in.

METHODS

The safety run-in was an open-label, single-arm trial in which six patients with early-stage luminal B BC received the following neo-adjuvant regimen: paclitaxel q1w×12 → doxorubicin/cyclophosphamide q2w×4; durvalumab (anti-programmed cell death receptor ligand 1 (PD-L1)) q4w×5; oleclumab (anti-CD73) q2w×4 → q4w×3 and 3×8 Gy SBRT to the primary tumor at week 5. Surgery must be performed 2-6 weeks after primary systemic treatment and adjuvant therapy was given per local guidelines, RT boost to the tumor bed was not allowed. Key inclusion criteria were: luminal BC, Ki67≥15% or histological grade 3, MammaPrint high risk, tumor size≥1.5 cm. Primary tumor tissue samples were collected at three timepoints: baseline, 1 week after SBRT and at surgery. Tumor-infiltrating lymphocytes, PD-L1 and CD73 were evaluated at each timepoint, and residual cancer burden (RCB) was calculated at surgery.

RESULTS

Six patients were included between November 2019 and March 2020. Median age was 53 years, range 37-69. All patients received SBRT and underwent surgery 2-4 weeks after the last treatment. After a median follow-up time of 2 years after surgery, one grade 3 adverse event (AE) was reported: pericarditis with rapid resolution under corticosteroids. No grade 4-5 AE were documented. Overall cosmetical breast evaluation after surgery was 'excellent' in four patients and 'good' in two patients. RCB results were 2/6 RCB 0; 2/6 RCB 1; 1/6 RCB 2 and 1/6 RCB 3.

CONCLUSIONS

This novel treatment combination was considered safe and is worth further investigation in a randomized phase II trial.

TRIAL REGISTRATION NUMBER

NCT03875573.

A narrative review for radiation oncologists to implement preoperative partial breast irradiation

The strategy to anticipate radiotherapy (RT) before surgery, for breast cancer (BC) treatment, has recently generated a renewed interest. Historically, preoperative RT has remained confined either to highly selected patients, in the context of personalized therapy, or to clinical research protocols. Nevertheless, in the recent years, thanks to technological advances and increased tumor biology understanding, RT has undergone great changes that have also impacted the preoperative settings, embracing the modern approach to breast cancer. In particular, the reappraisal of preoperative RT can be viewed within the broader view of personalized and tailored medicine. In fact, preoperative accelerated partial breast irradiation (APBI) allows a more precise target delineation, with less variability in contouring among radiation oncologists, and a smaller treatment volume, possibly leading to lower toxicity and to dose escalation programs. The aim of the present review, which represents a benchmark study for the AIRC IG-23118, is to report available data on different technical aspects of preoperative RT including dosimetric studies, patient's selection and set-up, constraints, target delineation and clinical results. These data, along with the ones that will become available from ongoing studies, may inform the design of the future trials and representing a step toward a tailored APBI approach with the potential to challenge the current treatment paradigm in early-stage BC.Trial registration: The study is registered at clinicaltrials.gov (NCT04679454).

Preoperative single fraction breast radiotherapy: Intra-fraction geometric uncertainties and dosimetric implications

PURPOSE

A preoperative breast robotic radiosurgery trial was concluded in our centre. Purposes of the present study were to evaluate retrospectively over the enrolled patients: i) respiratory patterns ii) tracking uncertainties iii) necessity of respiratory compensation iv) tracking errors dosimetric effects.

METHODS

22 patients were treated in 21 Gy single fraction using CyberKnife (CK) respiratory modelling and tracking (SynchronyResp) and data extracted from log-files. Respiratory motion and baseline drifts (BD) were analyzed. SynchronyResp uncertainties were computed and compared with errors simulated for CK fiducial tracking without respiratory compensation. Plans were perturbed by tracking errors and perturbed doses calculated on the planning CT scan in order to simulate the dosimetric consequences of intra-fraction errors.

RESULTS

After BD correction, respiratory amplitudes were below 5.5 mm except one value of 8 mm. 50% of patients showed BD above 3 mm. Standard deviations of SynchronyResp errors remained within 2.1 mm. Standard deviations of tracking errors without respiratory compensation were comparable and below 2.5 mm. Using a 3 mm PTV margin, perturbed CTV coverage was below 95% (93.7%) just for one patient. The latter case presented a large CTV-Skin interface. Perturbed OAR doses were always judged clinically acceptable.

CONCLUSION

Intra-fraction geometric uncertainties and their effects were quantified for breast neoadjuvant CK treatments. Data indicated that in the majority of cases respiratory compensation may be disabled without increasing uncertainties and reducing treatment time, provided that fiducial intra-fraction tracking is performed to account for BD. Dosimetric effects are mostly not clinically relevant.

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.

Pathologic Response to Neoadjuvant Sequential Chemoradiation Therapy in Locally Advanced Breast Cancer: Preliminary, Translational Results from the French Neo-APBI-01 Trial

Background: Radiation therapy (RT), a novel approach to boost the anticancer immune response, has been progressively evaluated in the neoadjuvant setting in breast cancer (BC). Purpose: We aimed to evaluate immunity-related indicators of response to neoadjuvant chemoradiation therapy (NACRT) in BC for better treatment personalization. Patients and Methods: We analyzed data of the first 42 patients included in the randomized phase 2 Neo-APBI-01 trial comparing standard neoadjuvant chemotherapy (NACT) and NACRT regimen in locally advanced triple-negative (TN) and luminal B (LB) subtype BC. Clinicopathological parameters, blood counts and the derived parameters, total tumor-infiltrating lymphocytes (TILs) and their subpopulation, as well as TP53 mutation status, were assessed as predictors of response. Results: Twenty-one patients were equally assigned to each group. The pathologic complete response (pCR) was 33% and 38% in the NACT and NACRT groups, respectively, with a dose-response effect. Only one LB tumor reached pCR after NACRT. Numerous parameters associated with response were identified, which differed according to the assigned treatment. In the NACRT group, baseline hemoglobin of ≥13 g/dL and body mass index of <26 were strongly associated with pCR. Higher baseline neutrophils-to-lymphocytes ratio, total TILs, and T-effector cell counts were favorable for pCR. Conclusion: This preliminary analysis identified LB and low-TIL tumors as poor responders to the NACRT protocol, which delivered RT after several cycles of chemotherapy. These findings will allow for amending the selection of patients for the trial and help better design future trials of NACRT in BC.

BOMB trial: First results of stereotactic radiotherapy to primary breast tumor in metastatic breast cancer patients

Aim

A prospective dose escalation trial was developed to evaluate the maximum tolerated dose of stereotactic body radiotherapy (SABRT) to primary breast cancer in stage IV disease. The aim of the present report was to describe safety and outcome of the first dose level cohort of patients.

Material and methods

Patients with histologically confirmed diagnosis of invasive breast carcinoma (biological immuno-histochemical profile: luminal and/or HER2 positive) and distant metastatic disease not progressing after 6 months of systemic therapy with a tumor CT or 5FDG-PET detectable were deemed eligible. The starting dose was 40 Gy in 5 fractions (level 1) because this dose proved to be safe in previous dose-escalation trial on adjuvant stereotactic body radiotherapy. The maximum dose level was chosen as 45 Gy in 5 fractions. Dose limiting toxicity was any grade 3 or worse toxicity according to CTCAE v.4. Time-to-event Keyboard (TITE-Keyboard) design (Lin and Yuan, Biostatistics 2019) was used to find the maximum tolerated dose (MTD). MTD was the dose of radiotherapy associated with a ≤ 20% rate pre-specified treatment-related dose-limiting toxicity (DLT).

Results

To date 10 patients have been treated at the starting dose level. Median age was 80 years (range 50-89). 7 patients had a luminal disease, while 3 patients had an HER2 positive disease. No patient suspended ongoing systemic treatment. No protocol defined DLTs were observed. Grade 2 skin toxicity occurred in 4 patients with diseases located close to or involving the skin. Median follow-up was 13 months and all 10 patients were evaluable for response: 5 achieved a complete response, 3 achieved a partial response and 2 showed a stable disease, all with a clinical benefit (resolution of skin retraction, bleeding and pain). The mean reduction in the sum of the largest diameters of target lesions was of 61.4% (DS=17.0%).

Conclusions

SABR to primary breast cancer seems feasible and is associated with symptoms reduction. Continued accrual to this study is needed to confirm the safety and assess the MTD.

Clinical trial registration

ClinicalTrials.gov, identifier NCT05229575.

Hypofractionation and SABR: 25 years of evolution in medical physics and a glimpse of the future

As we were invited to write an article for celebrating the 50^th Anniversary of Medical Physics journal, on something historically significant, commemorative, and exciting happening in the past decades, the first idea came to our mind is the fascinating radiotherapy paradigm shift from conventional fractionation to hypofractionation and stereotactic ablative radiotherapy (SABR). It is historically and clinically significant since as we all know this RT treatment revolution not only reduces treatment duration for patients, but also improves tumor control and cancer treatment outcomes. It is also commemorative and exciting for us medical physicists since the technology development in medical physics has been the main driver for the success of this treatment regimen which requires high precision and accuracy throughout the entire treatment planning and delivery. This article provides an overview of the technological development and clinical trials evolvement in the past 25 years for hypofractionation and SABR, with an outlook to the future improvement.

Preoperative Radio(Chemo)Therapy in Breast Cancer: Time to Switch the Perspective?

AIM

Radiation therapy represents, together with surgery and systemic treatment, the triad on which the current management of patients with breast cancer is based, achieving high control and survival rates. In recent years we have witnessed a (r)evolution in the conception of breast cancer treatment. The classic scheme of surgery followed by systemic treatment and radiotherapy is being subverted and it is becoming more and more frequent to propose the primary administration of systemic treatment before surgery, seeking to maximize its effect and favoring not only the performance of more conservative surgeries but also, in selected cases, increasing the rates of disease-free survival and overall survival. Radiotherapy is also evolving toward a change in perspective: considering preoperative primary administration of radiotherapy may be useful in selected groups. Advances in radiobiological knowledge, together with technological improvements that are constantly being incorporated into clinical practice, support the administration of increasingly reliable, precise, and effective radiotherapy, as well as its safe combination with antitumor drugs or immunotherapy in the primary preoperative context. In this paper, we present a narrative review of the usefulness of preoperative radiotherapy for breast cancer patients and the possibilities for its combination with other therapies.

Preoperative robotic radiosurgery for early breast cancer: Results of the phase II ROCK trial (NCT03520894)

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Preoperative partial breast irradiation treats well-defined target.

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Stereotactic body radiation therapy have been routinely implemented in clinical practice.

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No acute toxicity greater than grade 2 was recorded.

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A single 21 Gy dose preoperative robotic radiosurgery represents a feasible technique.

Background and purpose

Preoperative partial breast irradiation (PBI) has got the advantage of treating a well-defined target. We report the results of the phase II ROCK trial (NCT03520894), enrolling early breast cancer (BC) patients treated with preoperative robotic radiosurgery (prRS), in terms of acute and early late toxicity, disease control, and cosmesis.

Material and methods

The study recruited between 2018 and 2021 at our Radiation Oncology Unit. Eligible patients were 50 + years old BC, hormonal receptors positive/human epidermal growth factor receptor 2 negative (HR+/HER2-), sized up to 25 mm. The study aimed to prospectively assess the toxicity and feasibility of a robotic single 21 Gy-fraction prRS in preoperative setting.

Results

A total of 70 patients were recruited and 22 patients were successfully treated with pRS. Overall, three G1 adverse events (13.6 %) were recorded within 7 days from prRS. Three events (13.6 %) were recorded between 7 and 30 days, one G2 breast oedema and two G1 breast pain. No acute toxicity greater than G2 was recorded. Five patients experienced early late G1 toxicity. One patient reported G2 breast induration. No early late toxicity greater than G2 was observed. At a median follow up of 18 months (range 6–29.8), cosmetic results were scored excellent/good and fair in 14 and 5 patients, respectively, while 3 patients experienced a poor cosmetic outcome.

Conclusions

ROCK trial showed that a single 21 Gy dose prRS represents a feasible technique for selected patients affected by early BC, showing an acceptable preliminary toxicity profile.

Stereotactic partial breast irradiation in primary breast cancer: A comprehensive review of the current status and future directions

In selected low-risk breast cancer patients, accelerated partial breast irradiation (APBI) may represent an alternative option to the whole breast irradiation to reduce the volume of irradiated breast and total treatment duration. In the last few years, preliminary data from clinical trials showed that stereotactic partial breast radiotherapy may have the advantage to be less invasive compared to other APBI techniques, with preliminary good results in terms of local toxicity and cosmesis: the use of magnetic resonance, fiducial markers in the tumor bed, and new breast devices support both a precise definition of the target and radiation planning.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021257856, identifier CRD42021257856.

Survival comparison between postoperative and preoperative radiotherapy for stage I-III non-inflammatory breast cancer

To compare the survival benefit between preoperative and postoperative radiotherapy for stage I-III non-inflammatory breast cancer patients, we conducted a retrospective cohort study using surveillance, epidemiology and end results databases. Our study recruited patients who had been diagnosed with stage I-III breast cancer and underwent surgery and radiotherapy. The overall survival was calculated by Kaplan-Meier method. Cox risk model was used to determine the impact of radiotherapy according to stage, molecular subtype and other risk factors. Propensity score matching was used to balance measurable confounding factors. Of all the 411,279 enrolled patients varying from 1975 to 2016, 1712 patients received preoperative radiotherapy, and 409,567 patients received postoperative radiotherapy. Compared with the postoperative radiotherapy group, the preoperative radiotherapy group showed significantly higher risks of overall mortality and breast cancer-specific mortality. Survival differences in treatment sequences were correlated with stage, molecular subtypes and other risk factors. According to the results of this study, preoperative radiotherapy did not show a survival advantage, and postoperative radiotherapy is still the primary treatment. However, preoperative radiotherapy also has some theoretical advantages, such as phase reduction and recurrence reduction. Therefore, it is still worthy of further exploration.

Feasibility and Short-Term Toxicity of a Consecutively Delivered Five Fraction Stereotactic Body Radiation Therapy Regimen in Early-Stage Breast Cancer Patients Receiving Partial Breast Irradiation

Background

For appropriately selected patients with early-stage breast cancer (ESBC), accelerated partial breast irradiation (APBI) yields equivalent rates of ipsilateral breast tumor recurrence with mixed results in patient-rated cosmesis compared with whole-breast radiotherapy depending on the technique utilized. When utilizing external beam radiotherapy for APBI, techniques to reduce target margins and overall treatment volume are potentially important to decrease rates of long-term adverse cosmesis. Stereotactic body radiotherapy (SBRT) is a promising technique to deliver APBI because of its increased accuracy and sparing of uninvolved breast tissue. We report the initial results of a prospective clinical trial investigating feasibility, safety, and cosmetic outcomes of a daily five-fraction SBRT regimen for APBI.

Methods

Twenty-three patients with ESBC after lumpectomy who met APBI suitability were enrolled. During lumpectomy, a bioabsorbable three-dimensional fixed array tissue marker (BioZorb™, Hologic, Marlborough, MA) was placed for enhanced visualization of the cavity boundaries. Clinical target volume (CTV) was defined as the delineable cavity plus a 1-cm isotropic expansion followed by a 3-mm isotropic planning target volume (PTV) expansion. Patients received 30 Gy delivered in five planned consecutive daily fractions in either prone or supine positioning depending on individual anatomy. Two patients completed the five-fraction treatments in 9-day interval and 11-day interval due to external circumstances. A maximum PTV of 124cc was allowed to minimize incidence of fat necrosis. Plans utilized 10-MV flattening filter–free beams delivered on a Varian Edge linear accelerator. Local control, toxicity, and nurse/patient-scored cosmesis at pre-treatment baseline, 1 month post-treatment, and at subsequent 6-month intervals were recorded.

Results

Twenty-three patients were accrued at the time of submission with median follow-up of 6 months. No patients experienced grade ≥3 acute toxicity. Of the 10 events reported probably related to SBRT, nine were grade 1 (n = 9/10, 90%). There was no evidence of difference, deterioration, or change in patient or nurse-scored cosmesis from baseline to 1 and 6 months post-treatment. One patient developed nodal failure shortly after APBI.

Conclusions

Although longer follow-up is needed to assess long-term toxicity and local control, this study demonstrated a five-fraction SBRT regimen delivered over consecutive days is a safe, efficient, well-tolerated, and cosmetically favorable means of delivering APBI in suitable women.

Clinical Trial Registration

https://www.clinicaltrials.gov/ct2/show/NCT03643861, NCT03643861.

Quantitative Changes in Intratumoral Habitats on MRI Correlate With Pathologic Response in Early-stage ER/PR+ HER2- Breast Cancer Treated With Preoperative Stereotactic Ablative Body Radiotherapy

Objective

To quantitatively evaluate intratumoral habitats on dynamic contrast-enhanced (DCE) breast MRI to predict pathologic breast cancer response to stereotactic ablative body radiotherapy (SABR).

Methods

Participants underwent SABR treatment (28.5 Gy x3), baseline and post-SABR MRI, and breast-conserving surgery for ER/PR+ HER2- breast cancer. MRI analysis was performed on DCE T1-weighted images. MRI voxels were assigned eight habitats based on high (H) or low (L) maximum enhancement and the sequentially numbered dynamic sequence of maximum enhancement (H1-4, L1-4). MRI response was analyzed by percent tumor volume remaining (%VR = volume post-SABR/volume pre-SABR), and percent habitat makeup (%HM of habitat X = habitat X voxels/total voxels in the segmented volume). These were correlated with percent tumor bed cellularity (%TC) for pathologic response.

Results

Sixteen patients completed the trial. The %TC ranged 20%-80%. MRI %VR demonstrated strong correlations with %TC (Pearson R = 0.7-0.89). Pre-SABR tumor %HMs differed significantly from whole breasts (P = 0.005 to <0.00001). Post-SABR %HM of tumor habitat H4 demonstrated the largest change, increasing 13% (P = 0.039). Conversely, combined %HM for H1-3 decreased 17% (P = 0.006). This change correlated with %TC (P < 0.00001) and distinguished pathologic partial responders (≤70 %TC) from nonresponders with 94% accuracy, 93% sensitivity, 100% specificity, 100% positive predictive value, and 67% negative predictive value.

Conclusion

In patients undergoing preoperative SABR treatment for ER/PR+ HER2- breast cancer, quantitative MRI habitat analysis of %VR and %HM change correlates with pathologic response.

Single fraction ablative preoperative radiation treatment for early-stage breast cancer: the CRYSTAL study – a phase I/II clinical trial protocol

Background

Breast-conserving surgery (BCS) and whole breast radiation therapy (WBRT) are the standard of care for early-stage breast cancer (BC). Based on the observation that most local recurrences occurred near the tumor bed, accelerated partial breast irradiation (APBI), consisting of a higher dose per fraction to the tumor bed over a reduced treatment time, has been gaining ground as an attractive alternative in selected patients with low-risk BC. Although more widely delivered in postoperative setting, preoperative APBI has also been investigated in a limited, though increasing, and number of studies. The aim of this study is to test the feasibility, safety and efficacy of preoperative radiotherapy (RT) in a single fraction for selected BC patients.

Methods

This is a phase I/II, single-arm and open-label single-center clinical trial using CyberKnife. The clinical investigation is supported by a preplanning section which addresses technical and dosimetric issues. The primary endpoint for the phase I study, covering the 1st and 2nd year of the research project, is the identification of the maximum tolerated dose (MTD) which meets a specific target toxicity level (no grade 3–4 toxicity). The primary endpoint for the phase II study (3rd to 5th year) is the evaluation of treatment efficacy measured in terms of pathological complete response rate.

Discussion

The study will investigate the response of BC to the preoperative APBI from different perspectives. While preoperative APBI represents a form of anticipated boost, followed by WBRT, different are the implications for the scientific community. The study may help to identify good responders for whom surgery could be omitted. It is especially appealing for patients unfit for surgery due to advanced age or severe co-morbidities, in addition to or instead of systemic therapies, to ensure long-term local control. Moreover, patients with oligometastatic disease synchronous with primary BC may benefit from APBI on the intact tumor in terms of tumor progression free survival. The study of response to RT can provide useful information about BC radiobiology, immunologic reactions, genomic expression, and radiomics features, to be tested on a larger scale.

Trial registration

The study was prospectively registered at clinicaltrials.gov (NCT04679454).

A Novel Approach for the Discovery of Biomarkers of Radiotherapy Response in Breast Cancer

Radiotherapy (RT) is an important treatment modality for the local control of breast cancer (BC). Unfortunately, not all patients that receive RT will obtain a therapeutic benefit, as cancer cells that either possess intrinsic radioresistance or develop resistance during treatment can reduce its efficacy. For RT treatment regimens to become personalised, there is a need to identify biomarkers that can predict and/or monitor a tumour's response to radiation. Here we describe a novel method to identify such biomarkers. Liquid chromatography-mass spectrometry (LC-MS) was used on conditioned media (CM) samples from a radiosensitive oestrogen receptor positive (ER⁺) BC cell line (MCF-7) to identify cancer-secreted biomarkers which reflected a response to radiation. A total of 33 radiation-induced secreted proteins that had higher (up to 12-fold) secretion levels at 24 h post-2 Gy radiation were identified. Secretomic results were combined with whole-transcriptome gene expression experiments, using both radiosensitive and radioresistant cells, to identify a signature related to intrinsic radiosensitivity. Gene expression analysis assessing the levels of the 33 proteins showed that 5 (YBX3, EIF4EBP2, DKK1, GNPNAT1 and TK1) had higher expression levels in the radiosensitive cells compared to their radioresistant derivatives; 3 of these proteins (DKK1, GNPNAT1 and TK1) underwent in-lab and initial clinical validation. Western blot analysis using CM samples from cell lines confirmed a significant increase in the release of each candidate biomarker from radiosensitive cells 24 h after treatment with a 2 Gy dose of radiation; no significant increase in secretion was observed in the radioresistant cells after radiation. Immunohistochemistry showed that higher intracellular protein levels of the biomarkers were associated with greater radiosensitivity. Intracellular levels were further assessed in pre-treatment biopsy tissues from patients diagnosed with ER⁺ BC that were subsequently treated with breast-conserving surgery and RT. High DKK1 and GNPNAT1 intracellular levels were associated with significantly increased recurrence-free survival times, indicating that these two candidate biomarkers have the potential to predict sensitivity to RT. We suggest that the methods highlighted in this study could be utilised for the identification of biomarkers that may have a potential clinical role in personalising and optimising RT dosing regimens, whilst limiting the administration of RT to patients who are unlikely to benefit.

Neo-CheckRay: radiation therapy and adenosine pathway blockade to increase benefit of immuno-chemotherapy in early stage luminal B breast cancer, a randomized phase II trial

BACKGROUND

Residual breast cancer after neo-adjuvant chemotherapy (NACT) predicts disease outcome and is a surrogate for survival in aggressive breast cancer (BC) subtypes. Pathological complete response (pCR) rate, however, is lower for luminal B BC in comparison to the triple negative (TNBC) and HER2+ subtypes. The addition of immune checkpoint blockade (ICB) to NACT has the potential to increase pCR rate but is hampered by the lower immunogenicity of luminal B BC. Novel strategies are needed to stimulate the immune response and increase the response rate to ICB in luminal B BC.

METHODS

The Neo-CheckRay trial is a randomized phase II trial investigating the impact of stereotactic body radiation therapy (SBRT) to the primary breast tumor in combination with an anti-CD73 (oleclumab) to increase response to anti PD-L1 (durvalumab) and NACT. The trial is designed as a three-arm study: NACT + SBRT +/- durvalumab +/- oleclumab. The result at surgery will be evaluated using the residual cancer burden (RCB) index as the primary endpoint. Six patients will be included in a safety run-in, followed by a randomized phase II trial that will include 136 evaluable patients in 3 arms. Inclusion is limited to luminal B breast cancers that are MammaPrint genomic high risk.

DISCUSSION

combination of ICB with chemotherapy in luminal B BC might benefit from immune priming agents to increase the response rate. As none have been identified so far, this phase II trial will evaluate SBRT and oleclumab as potential immune priming candidates.

TRIAL REGISTRATION

trial registered on ClinicalTrials.gov ( NCT03875573 ) on March 14th, 2019.

MRI Response to Pre-operative Stereotactic Ablative Body Radiotherapy (SABR) in Early Stage ER/PR+ HER2- Breast Cancer correlates with Surgical Pathology Tumor Bed Cellularity

OBJECTIVE

This study evaluates breast MRI response of ER/PR+ HER2- breast tumors to pre-operative SABR with pathologic response correlation.

METHODS

Women enrolled in a phase 2 single institution trial of SABR for ER/PR+ HER2- breast cancer were retrospectively evaluated for radiologic-pathologic correlation of tumor response. These patients underwent baseline breast MRI, SABR (28.5 Gy in 3 fractions), follow-up MRI 5 to 6 weeks post-SABR, and lumpectomy. Tumor size and BI-RADS descriptors on pre and post-SABR breast MRIs were compared to determine correlation with surgical specimen % tumor cellularity (%TC). Reported MRI tumor dimensions were used to calculate percent cubic volume remaining (%VR). Partial MRI response was defined as a BI-RADs descriptor change or %VR ≤ 70%, while partial pathologic response (pPR) was defined as %TC ≤ 70%.

RESULTS

Nineteen patients completed the trial, and %TC ranged 10% to 80%. For BI-RADS descriptor analysis, 12 of 19 (63%) showed change in lesion or kinetic enhancement descriptors post-SABR. This was associated with lower %TC (29% vs. 47%, P = .042). BI-RADS descriptor change analysis also demonstrated high PPV (100%) and specificity (100%) for predicting pPR to treatment (sensitivity 71%, accuracy 74%), but low NPV (29%). MRI %VR demonstrated strong linear correlation with %TC (R = 0.70, P < .001, Pearson's Correlation) and high accuracy (89%) for predicting pPR (sensitivity 88%, specificity 100%, PPV 100%, and NPV 50%).

CONCLUSION

Evaluating breast cancer response on MRI using %VR after pre-operative SABR treatment can help identify patients benefiting the most from neoadjuvant radiation treatment of their ER/PR+ HER2- tumors, a group in which pCR to neoadjuvant therapy is rare.

Surgeon's Perspective to Local Therapy in Oligometastatic Cancer

Oligometastatic cancer has been recognized as a distinct clinical entity for over 100 years. For decades surgeons have been devising strategies to identify patients with oligmetastatic cancer that have the potential to be cured by surgically removing the oligometastases ("curative intent metastasectomy"). More recently, several studies have suggested there may be benefits to local therapy in oligometastatic cancer patients that are less likely to be cured. This has transformed the practice of local therapy in this setting away from "curative intent" to a broader purpose of "lesion-specific cytoreduction." As a result, the pool of oligometastatic patients eligible for local therapy has been expanded. However, the boundaries that had previously framed the practice of local therapy in oligometastatic cancer have been obscured. The following is a single surgeon's attempt to align the promise of this expanded role of local therapy, with the principles of risk-benefit deliberation that are intrinsic to the surgical discipline.

Stereotactic body radiotherapy in Cyberknife® for partial breast irradiation: a review

Introduction:

Partial breast irradiation (PBI) can reduce the volume of treatment and number of treatment sessions in low-risk breast cancer patients. Stereotactic body radiotherapy (SBRT) allows the administration of high doses per fraction thereby reducing the number of fractions and reducing the dose to the surrounding tissues. The objective of this study is to review the literature on the use of SBRT in PBI using the Cyberknife® (CK) unit.

Material and methods:

In this review, we analysed the literature in PubMed and MEDLINE with articles published in the last 10 years. All citations were evaluated for relevant content and validity.

Results:

We include articles in the English language with information about PBI, SBRT in PBI, the use of the CK unit in PBI and other applications of SBRT in breast carcinoma. A total of 68 articles were found and 28 articles were selected for inclusion in this review.

Conclusions:

The treatment of PBI using the CK unit has clear advantages in reducing the treatment volume, and therefore theoretically reducing side effects and good cosmetic results with adequate tumour control. However, the placement of fiducial markers is necessary, requiring an adequate learning curve for the placement of the markers and longer treatment times.

Radiation therapy and immunotherapy in breast cancer treatment: preliminary data and perspectives

Introduction: The discovery of the major role of the immune system in the tumor process has led to the development of therapeutic strategies with immunotherapy. The potential systemic role of radiotherapy, (RT) used for a long time for its local action, based on its impact on immunity, is now better understood. The combination of immunotherapy and radiation therapy is currently a field of sustained research programs and has shown successful results, in non-small cell lung cancer, for example. Breast cancer (BC) was wrongly considered poorly immunogenic and put aside during accelerating progress in this new area of treatment.Areas covered: This review provides an overview of pre-clinical and clinical rationales to associate immunotherapy with radiation therapy in the management of breast cancer.Expert opinion: Immunotherapy has been used only recently in breast cancer, but clinical trials have yet to determine the place of this treatment. RT may be useful to enhance the response of breast tumors to immunotherapy. This new approach in breast cancer management is currently based on limited data but should be further investigated, especially in triple-negative breast cancer and in the neoadjuvant setting.

Improved Survival Associated with Local Tumor Response Following Multisite Radiotherapy and Pembrolizumab: Secondary Analysis of a Phase I Trial

PURPOSE

Multisite stereotactic body radiotherapy followed by pembrolizumab (SBRT+P) has demonstrated safety in advanced solid tumors (ASTs). However, no studies have examined the relationships between irradiated tumor response, SBRT-induced tumor gene expression, and overall survival (OS).

PATIENTS AND METHODS

Patients with AST received SBRT (30-50 Gy in 3-5 fractions) to two to four metastases followed by pembrolizumab (200 mg i.v. every 3 weeks). SBRT was prescribed to a maximum tumor volume of 65 mL. Small metastases received the complete prescribed coverage (complete-Rx), while larger metastases received partial coverage (partial-Rx). Treated metastasis control (TMC) was defined as a lack of progression for an irradiated metastasis. Landmark analysis was used to assess the relationship between TMC and OS. Thirty-five biopsies were obtained from 24 patients: 19 pre-SBRT and 16 post-SBRT (11 matched) prior to pembrolizumab and were analyzed via RNA microarray.

RESULTS

Sixty-eight patients (139 metastases) were enrolled with a median follow-up of 10.4 months. One-year TMC was 89.5% with no difference between complete-Rx or partial-Rx. On multivariable analysis, TMC was independently associated with a reduced risk for death (HR, 0.36; 95% confidence interval, 0.17-0.75; P = 0.006). SBRT increased expression of innate and adaptive immune genes and concomitantly decreased expression of cell cycle and DNA repair genes in the irradiated tumors. Elevated post-SBRT expression of DNASE1 correlated with increased expression of cytolytic T-cell genes and irradiated tumor response.

CONCLUSIONS

In the context of SBRT+P, TMC independently correlates with OS. SBRT impacts intratumoral immune gene expression associated with TMC. Randomized trials are needed to validate these findings.

Optimizing Radiation Therapy to Boost Systemic Immune Responses in Breast Cancer: A Critical Review for Breast Radiation Oncologists

Immunotherapy using immune checkpoint blockade has revolutionized the treatment of many types of cancer. Radiation therapy (RT)-particularly when delivered at high doses using newer techniques-may be capable of generating systemic antitumor effects when combined with immunotherapy in breast cancer. These systemic effects might be due to the local immune-priming effects of RT resulting in the expansion and circulation of effector immune cells to distant sites. Although this concept merits further exploration, several challenges need to be overcome. One is an understanding of how the heterogeneity of breast cancers may relate to tumor immunogenicity. Another concerns the need to develop knowledge and expertise in delivery, sequencing, and timing of RT with immunotherapy. Clinical trials addressing these issues are under way. We here review and discuss the particular opportunities and issues regarding this topic, including the design of informative clinical and translational studies.

Definitive single fraction stereotactic ablative radiotherapy for inoperable early-stage breast cancer: A case report

We review a case of inoperable early stage breast cancer treated definitively with the use of stereotactic ablative radiotherapy (SABR). A 57-year-old female with a history of decompensated cirrhosis with early stage breast cancer was treated with 25 Gy in one fraction. At her 7-month follow up visit, there was a complete resolution of disease on imaging. This case represents a novel approach for the treatment of breast cancer with SABR when surgery is contraindicated.

[Adjuvant and neoadjuvant radiotherapy in breast cancer: A literaure review and update on the state of the evidence in 2020]

Radiation therapy has benefited from many developments over the past 20 years. These developments are mainly linked to the technology, imaging and informatics evolutions which allow better targets definitions, ensure better organs-at-risk sparing and excellent reproducibility of treatments, with a perfect control of patient positioning. In breast cancer radiotherapy, the evolution was marked by the possibility of reducing the duration of treatments from 6-7 to 3-4 weeks by using hypofractionated regimens, or by further reducing the irradiation to one week when treatment is solely focalised to the tumour bed. This concept of accelerated partial breast irradiation has challenged the paradigm of the obligation to irradiate the whole breast after conservative surgery in all patients. In addition, the technical mastery of accelerated partial breast irradiation and the development of stereotactic radiotherapy techniques are currently contributing to the development of research projects in neoadjuvant settings. Thus, numerous ongoing studies are evaluating the impact of high-dose preoperative tumour irradiation, alone or in combination with systemic treatments, on biological tumor changes, on anti-tumour immunity, and on the pathologic complete response, which is considered as predictive of better long-term survival in some molecular breast cancer subtypes. In this review, we discuss all these developments which allow breast radiation therapy to enter the era of personalisation of treatments in oncology.

Update on Partial Breast Irradiation

For early-stage breast cancer, partial breast irradiation (PBI) allows for reduction in the irradiated volume of normal tissues by confining the radiation target to the area surrounding the lumpectomy cavity after breast-conserving surgery. This approach has been supported by phase 2 data. However, widespread adoption of PBI has awaited the results of randomized controlled trials. This review discusses the results of randomized controlled trials comparing whole breast irradiation to PBI, including the recently published National Surgical Adjuvant Breast and Bowel Project (NSABP) B39/Radiotherapy Oncology Group (RTOG) 0413, and the Canadian RAPID trials. PBI techniques, dose/fractionation schedules, and patient selection are also reviewed.

Measuring the Integration of Stereotactic Ablative Radiotherapy Plus Surgery for Early-Stage Non-Small Cell Lung Cancer: A Phase 2 Clinical Trial

Importance

Stereotactic ablative radiotherapy (SABR) is a standard treatment option in patients with medically inoperable early-stage non-small cell lung cancer (NSCLC), yet the pathologic complete response (pCR) rate after SABR is unknown. Neoadjuvant SABR in patients with cancer who are fit for resection has been hypothesized to improve local control and induce antitumor immune activity, potentially leading to better outcomes.

Objectives

To determine the pCR rate after SABR and to assess oncologic and toxicity outcomes after a combined approach of neoadjuvant SABR followed by surgery.

Design, Setting, and Participants

A phase 2, single-arm trial, with patient accrual from September 30, 2014, to August 15, 2017 (median follow-up, 19 months), was performed at a tertiary academic cancer center. Patients 18 years or older with T1T2N0M0 NSCLC and good performance status, with adequate pulmonary reserve to undergo surgical resection, were studied.

Interventions

Patients underwent neoadjuvant SABR using a risk-adapted fractionation scheme followed by surgery 10 weeks later.

Main Outcomes and Measures

The pCR rate as determined by hematoxylin-eosin staining.

Results

Forty patients (mean [SD] age, 68 [8] years; 23 [58%] female) were enrolled. Thirty-five patients underwent surgery and were evaluable for the primary end point. The pCR rate was 60% (95% CI, 44%-76%). The 30- and 90-day postoperative mortality rates were both 0%. Grade 3 or 4 toxic effects occurred in 7 patients (18%). In patients receiving surgery, 2-year overall survival was 77% (95% CI, 48%-91%), local control was 100% (95% CI, not defined), regional control was 53% (95% CI, 22%-76%), and distant control was 76% (95% CI, 45%-91%). Quality of life did not decline after treatment, with no significant changes in mean Functional Assessment of Cancer Therapy for Lung-Trial Outcome Index score during the first year of follow-up.

Conclusions and Relevance

The pCR rate after SABR for early-stage NSCLC was 60%, lower than hypothesized. The combined approach had toxic effects comparable to series of surgery alone, and there was no perioperative mortality. Further studies are needed to evaluate this combined approach compared with surgical resection alone.

Trial Registration

ClinicalTrials.gov identifier: NCT02136355.

Preoperative radiotherapy: A paradigm shift in the treatment of breast cancer? A review of literature

The standard of care for early-stage breast cancer (BC) consists of breast-conserving surgery followed by postoperative irradiation. Recently, the concept of changing the usual sequence of treatment components in BC RT has been investigated. Potential advantages of preoperative RT in BC include a possible tumor downstaging with improved surgical cosmetic outcomes, accurate tumor site identification and better target volume delineation. Furthermore, preoperative RT could serve as a tool for treatment stratification for de-escalation of treatments in the event of pathological complete response. The present literature review analyzed the available clinical data regarding the potential impact of preoperative RT. Overall, available clinical evidence of preoperative RT in BC remains limited, deriving mostly from retrospective case series. Nevertheless, the experiences prove the feasibility of the preoperative RT approach and confirm the efficacy in almost all analyzed studies, including experiences using higher prescription RT doses or RT in combination with systemic therapy.

Robotic Stereotactic Boost in Early Breast Cancer, a Phase 2 Trial

PURPOSE

To evaluate the feasibility and toxicity of a single-fraction 8-Gy stereotactic boost after whole-breast irradiation in early breast cancer. The primary aim of this phase 2 study was to evaluate cutaneous breast toxicity using National Cancer Institute Common Terminology Criteria for Adverse Events (version 4) 3 months after the boost. Secondary objectives were local control, survival, and patient-reported quality of life using the European Organisation for Research and Treatment of Cancer QLQ-C30 and breast-specific European Organisation for Research and Treatment of Cancer QLQ-BR 23 questionnaires.

METHODS AND MATERIALS

Patients with invasive ductal or lobular pT1-2 breast cancer treated with lumpectomy with clear margins and pN0 were included. Patients requiring chemotherapy were excluded.

RESULTS

Twenty-eight eligible patients received the planned boost, and 26 had hormonal therapy. The procedure was technically successful without procedural complications. A median of 3 fiducials were tracked, and 115 beams were used. There were 22 acute grade 1 breast skin toxicities, including fibrosis, pain, erythema, or pigmentation. There were 2 acute grade 2 erythemas. Median skin boost dose was inversely correlated with acute skin toxicity (P = .028). QLQ-C30 scores revealed acute dyspnea and arm symptoms without correlation to the boost dose. Breast symptom QLQ-BR23 scores did not deteriorate, although upset with hair loss and systemic side effects of hormonal therapy were observed. After a median follow-up of 38 months, 1 patient had in-boost-field relapse, and there were 5 late grade 1 and 1 grade 2 skin toxicities.

CONCLUSIONS

Single-fraction stereotactic boost after conventional whole-breast irradiation in early breast cancer is feasible with minor toxicities. Quality of life and specific breast items showed excellent patient acceptance.

Personalizing Radiation Treatment Delivery in the Management of Breast Cancer

Long-term data establishes the efficacy of radiotherapy in the adjuvant management of breast cancer. New dose and fractionation schemas have evolved and are available, each with unique risks and rewards. Current efforts are ongoing to tailor radiotherapy to the unique biology of breast cancer. In this review, we discuss our efforts to personalize radiotherapy dosing using genomic data and the implications for future clinical trials. We also explore immune mechanisms that may contribute to a tumor's unique radiation sensitivity or resistance.

Horizon scanning implanted biosensors in personalising breast cancer management: First pilot study of breast cancer patients views

AIMS

This study aimed to explore breast cancer patients' understanding and acceptability of implanted biosensors (BS) within the primary tumour to personalise adjuvant radiotherapy, and to determine optimal design and number of BS, and evaluate potential clinical benefits as well as concerns about tolerance, toxicity, dwell time, and confidentiality of data.

PATIENTS AND METHODS

A total of 32 patients treated by surgery (29 breast conserving, 3 mastectomy), postoperative radiotherapy and systemic therapy for early breast cancer, were recruited from a posttreatment radiotherapy clinic at a cancer centre. Patients participated in semistructured interviews. Interview transcripts were analysed using qualitative methods.

RESULTS

Participants were aged 39 to 87 years, with a median age of 62 years. Most (N = 23[72%]) were unfamiliar with biosensors. The majority (N = 29[90.6%]) were supportive of the technology's potential use in future breast cancer treatment and were willing to accept biosensors (N = 28[88%]) if they were endorsed by their breast cancer consultant. Only 3 patients expressed concerns, predominantly about uncertainties on their role in the diagnostic and treatment pathway. Patients were flexible about the size and shape of BS, but had a preference for small size (N = 28 [87.5%]). Most (N = 22[69%]) would accept implantation of more than 5 BS and were flexible (N = 22[69%]) about indefinite dwell time. Patients had a strong preference for wireless powering of the BS (N = 28[87.5%]). Few had concerns about loss of confidentiality of data collected. All patients considered biosensors to be potentially of important clinical benefit.

CONCLUSIONS

While knowledge of biosensors was limited, patients were generally supportive of biosensors implanted within the primary tumour to collect data that might personalise and improve breast cancer radiotherapy in future.

Establishing the Role of Stereotactic Ablative Body Radiotherapy in Early-Stage Breast Cancer

Stereotactic ablative body radiotherapy (SABR) has a role as definitive therapy in many tumor sites; however, its role in the treatment of breast cancer is less well explored. Currently, SABR has been investigated in the neoadjuvant and adjuvant setting with a number of ongoing feasibility studies. However, its use comes with a number of radiobiological and technical challenges that require further evaluation. We have learned much from other extracranial disease sites such as lung, brain, and spine, where definitive treatment with SABR has shown encouraging outcomes. In women with breast cancer, SABR may eliminate the need for invasive surgery, reducing healthcare costs and hospital stays and providing an additional curative option for early-stage disease. This poses the following question: is there a role for SABR as a definitive therapy in breast cancer?

Projected Improvements in Accelerated Partial Breast Irradiation Using a Novel Breast Stereotactic Radiotherapy Device: A Dosimetric Analysis

Accelerated partial breast irradiation has caused higher than expected rates of poor cosmesis. At our institution, a novel breast stereotactic radiotherapy device has demonstrated dosimetric distributions similar to those in brachytherapy. This study analyzed comparative dose distributions achieved with the device and intensity-modulated radiation therapy accelerated partial breast irradiation. Nine patients underwent computed tomography simulation in the prone position using device-specific immobilization on an institutional review board–approved protocol. Accelerated partial breast irradiation target volumes (planning target volume_10mm) were created per the National Surgical Adjuvant Breast and Bowel Project B-39 protocol. Additional breast stereotactic radiotherapy volumes using smaller margins (planning target volume_3mm) were created based on improved immobilization. Intensity-modulated radiation therapy and breast stereotactic radiotherapy accelerated partial breast irradiation plans were separately generated for appropriate volumes. Plans were evaluated based on established dosimetric surrogates of poor cosmetic outcomes. Wilcoxon rank sum tests were utilized to contrast volumes of critical structures receiving a percentage of total dose (Vx). The breast stereotactic radiotherapy device consistently reduced dose to all normal structures with equivalent target coverage. The ipsilateral breast V20-100 was significantly reduced (P < .05) using planning target volume_10mm, with substantial further reductions when targeting planning target volume_3mm. Doses to the chest wall, ipsilateral lung, and breast skin were also significantly lessened. The breast stereotactic radiotherapy device’s uniform dosimetric improvements over intensity-modulated accelerated partial breast irradiation in this series indicate a potential to improve outcomes. Clinical trials investigating this benefit have begun accrual.

Preoperative Radiotherapy Is Not Associated with Increased Post-mastectomy Short-term Morbidity: Analysis of 77,902 Patients

Supplemental Digital Content is available in the text.

Background:

Neoadjuvant radiotherapy (NRT) enhances breast-conserving surgery outcomes, reducing local recurrence of breast cancer and increasing median survival. However, its effect on postoperative morbidity remains under-studied. We sought to assess the impact of NRT on 30-day postoperative morbidity after mastectomy.

Methods:

We analyzed data from women undergoing mastectomy (with or without immediate reconstruction) using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) 2005–2011 datasets. ACS-NSQIP is a prospective, risk-adjusted, outcomes-based registry. Data included demographic and perioperative factors. Outcomes studied included surgical site (wound and prosthesis/flap complications), systemic (cardiac, respiratory, neurological, urinary, and venous thromboembolism events), and overall morbidity. Logistic regression was used to estimate the unadjusted odds ratio (uOR) and adjusted odds ratio (aOR) between NRT and postoperative 30-day morbidity.

Results:

The study population included 77,902 women, of which 61,039 (78.4%) underwent mastectomy only and 16,863 (21.6%) underwent mastectomy with immediate breast reconstruction. NRT was administered to 266 (0.4%) mastectomy-only and 75 (0.4%) immediate breast reconstruction patients. In the mastectomy-only group, there were no significant differences in the rates of postoperative surgical site morbidity (aOR = 1.41; 95% confidence interval (CI): 0.76–2.63; P = 0.276), systemic morbidity (aOR = 0.72; 95% CI: 0.40–1.26; P = 0.252), and overall morbidity (aOR = 0.85; 95% CI: 0.54–1.33; P = 0.477) between NRT and control groups. Similarly, no significant differences were found for these three outcomes in the immediate breast reconstruction population. Statistical power for every comparison was >80%.

Conclusions:

This study suggests that NRT is not associated with significantly higher 30-day postoperative complications among breast cancer patients undergoing mastectomy with or without immediate breast reconstruction.

New Techniques for Irradiating Early Stage Breast Cancer: Stereotactic Partial Breast Irradiation

Several improvements in breast cancer radiation delivery have been realized using new techniques over the past several decades. As an example, for early stage disease, there has been active investigation of partial breast irradiation (PBI) vs whole breast irradiation. Although still investigational, PBI reduces the treatment volumes, doses to organs at risk, and may improve cosmesis. Over the past 2 decades PBI has been delivered via interstitial brachytherapy, intracavitary brachytherapy, intraoperative radiation therapy, or 3-dimensional external beam radiation therapy. More recently, there has been growing evidence that supports stereotactic body radiation therapy as a safe and effective new treatment for early stage breast cancer. This article describes this new treatment opportunity and reviews the emerging data of stereotactic partial breast irradiation.

Preoperative Accelerated Partial Breast Irradiation for Early-Stage Breast Cancer: Preliminary Results of a Prospective, Phase 2 Trial

PURPOSE

To assess the feasibility of utilizing 3-dimensional conformal accelerated partial-breast irradiation (APBI) in the preoperative setting followed by standard breast-conserving therapy.

PATIENTS AND METHODS

This was a prospective trial testing the feasibility of preoperative APBI followed by lumpectomy for patients with early-stage invasive ductal breast cancer. Eligible patients had T1-T2 (<3 cm), N0 tumors. Patients received 38.5 Gy in 3.85-Gy fractions delivered twice daily. Surgery was performed >21 days after radiation therapy. Adjuvant therapy was given as per standard of care.

RESULTS

Twenty-seven patients completed treatment. With a median follow-up of 3.6 years (range, 0.5-5 years), there have been no local or regional failures. A complete pathologic response according to hematoxylin and eosin stains was seen in 4 patients (15%). There were 4 grade 3 seromas. Patient-reported cosmetic outcome was rated as good to excellent in 79% of patients after treatment.

CONCLUSIONS

Preoperative 3-dimensional conformal radiation therapy-APBI is feasible and well tolerated in select patients with early-stage breast cancer, with no reported local recurrences and good to excellent cosmetic results. The pathologic response rates associated with this nonablative APBI dose regimen are particularly encouraging and support further exploration of this paradigm.

External beam radiation techniques for breast cancer in the new millennium: New challenging perspectives

Radiation therapy in breast cancer has evolved dramatically over the past century. It has traveled a long path touching different milestones and taking unprecedented turns. At the end, a fine tune of clinical understanding, skill, technological advancement and translation of radiobiological understanding to clinical outcome has taken place. What all these have given is better survival with quality survivorship. It is thus prudent to understand breast irradiation in a new perspective suitable for the current millennium.

Stereotactic breast irradiation with kilovoltage x-ray beams

The purpose of this work is to determine, using Monte Carlo simulation and a realistic patient model, the characteristics of the resultant absorbed dose distributions when breast tumors are irradiated using small-field stereotactic body radiation therapy (SBRT) with kilovoltage x-ray beams instead of the standard megavoltage energies currently in use. The Rensselaer Polytechnic Institute (RPI) female phantom was used to model a pair of small-field SBRT breast treatments: in one treatment the tumor at depth and another one with the tumor located close to the breast surface. Each treatment consisted of 300 circular beams aimed at the tumor from a plurality of positions. The PENELOPE Monte Carlo code was used to determine the absorbed dose distribution for each beam and subsequently an optimization algorithm determined each beam weight according to a set of prescription goals. Both kilo- and megavoltage beam treatments were modeled, the latter to be used as a reference. Cumulative dose-volume histograms for eleven structures were used to compare the kilovoltage and reference treatments. Integral dose values are also reported. Absorbed dose distributions for the target volumes as well as the organs at risk were within the parameters reported in a clinical trial for both treatments. While for the ipsilateral healthy breast tissue the megavoltage treatment does offer an advantage in terms of less volume irradiated to intermediate doses, for the contralateral structures, breast and lung, the low penetration ability of the kilovoltage treatment results in a lower maximum dose. Skin dose is higher for the kilovoltage treatment but still well within the tolerance limits reported in the clinical trial.

Novel and Highly Compressed Schedules for the Treatment of Breast Cancer

Our thinking about radiotherapy (RT) for early-stage breast cancer has evolved considerably over the last several years. Increasingly patients and physicians together are making the decision to use altered fractionation rather than standard 6-7 weeks of conventional whole breast treatment plus lumpectomy bed boost. Adjuvant hypofractionated whole breast irradiation is now viewed as a preferred strategy for many eligible women, and can be completed in 3-4 weeks. Adjuvant accelerated partial breast irradiation is another alternative that is typically delivered in 8-10 fractions over 4-5 days. With improvements in delivery techniques, there has been renewed interest in shortening treatment times even further, with novel intraoperative approaches and ultrashort courses of external beam RT. This article provides a summary of the status and future directions in intraoperative and ultrashort course RT schedules used in the treatment of breast cancer. Outlined are the benefits as well as the drawbacks of these techniques for abbreviated breast RT.

Robotic stereotactic radioablation of breast tumors: Influence of beam size on the absorbed dose distributions

Robotic stereotactic radioablation (RSR) therapy for breast tumors has been shown to be an effective treatment strategy when applied concomitantly with chemotherapy, with the purpose of reducing the tumor volume thus making it more amenable for breast conserving surgery. In this paper we used Monte Carlo simulation within a realistic patient model to determine the influence that the variation in beam collimation radius has on the resultant absorbed dose distributions for this type of treatment. Separate optimized plans were obtained for treatments using 300 circular beams with radii of 0.5 cm, 0.75 cm, 1.0 cm and 1.5 cm. Cumulative dose volume histograms were obtained for the gross, clinical and planning target volumes as well as for eight organs and structures at risk. Target coverage improves as the collimator size is increased, at the expense of increasing the volume of healthy tissue receiving mid-level absorbed doses. Interestingly, it is found that the maximum dose imparted to the skin is highly dependent on collimator size, while the dosimetry of other structures, such as both the ipsilateral and contralateral lung tissue are basically unaffected by a change in beam size.