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

Neoadjuvant Radiotherapy and Endocrine Therapy for Oestrogen Receptor Positive Breast Cancers: The Neo-RT Feasibility Study

AIMS

To establish the safety and feasibility of delivering neoadjuvant radiotherapy and endocrine therapy for oestrogen receptor-positive breast cancers with palpable size 20mm or greater, for which radiotherapy might facilitate more conservative surgery.

MATERIALS AND METHODS

A single-arm feasibility study was conducted. Patients received whole breast radiotherapy with or without radiotherapy to nodal areas. Dose/fractionation was 40Gy in 15 fractions over 3 weeks, with or without either a simultaneous integrated boost to 48Gy or sequential boost to the tumour bed. This was followed by endocrine treatment for 20 weeks, then surgery. The primary endpoint of the study was the proportion of patients successfully completing neoadjuvant radiotherapy and endocrine treatment followed by breast surgery. Response and toxicity endpoints including mastectomy rate, peri/postoperative complications, and pathological response were also evaluated. The primary analysis is descriptive. The study regimen would be considered feasible if more than 70% of patients completed treatment, while it might not be considered feasible if less than 50% did so. With a one-sided 5% significance level and 80% power, a maximum of 43 patients would be required to detect a rate of ≤50% vs ≥70%.

RESULTS

14 patients were recruited out of the planned 43. Due to slow recruitment, particularly during the COVID-19 pandemic, the decision was made to stop the trial in October 2021. One registered patient was found to be ineligible before starting treatment. 13/13 patients (100%, 90% CI: 75.3%, 100%) who received any trial treatment successfully completed all trial treatments. The lower bound of the Clopper-Pearson (exact) 90% confidence interval was 79%, indicating that the primary endpoint would have been met if the planned recruitment had been achieved. 3/13 patients underwent mastectomy. 7/13 had more conservative surgery than had been planned at baseline. 4/13 patients experienced any peri/postoperative complication. The only acute radiotherapy toxicities reported were grade 1/2 dermatitis and grade 1 fatigue. Long-term breast outcomes were clinician assessed as none/mild at all timepoints in 12/13 patients. All tumours showed evidence of some pathological response to treatment, but none had a pathological complete response.

CONCLUSION

This treatment schedule is likely feasible. It is difficult to draw strong conclusions on safety/toxicity given the small numbers, but these seem in keeping with other recent reports of neoadjuvant breast radiotherapy.

Escalation and De-Escalation of Adjuvant Radiotherapy in Early Breast Cancer: Strategies for Risk-Adapted Optimization

Postoperative radiotherapy (RT) is recommended after breast-conserving surgery and mastectomy (with risk factors). Consideration of pros and cons, including potential side effects, demands the optimization of adjuvant RT and a risk-adapted approach. There is clear de-escalation in fractionation-hypofractionation should be considered standard. For selected low-risk situations, PBI only or even the omission of RT might be appropriate. In contrast, tendencies toward escalating RT are obvious. Preoperative RT seems attractive for patients in whom breast reconstruction is planned or for defining the tumor location more precisely with the potential of giving ablative doses. Dose escalation by a (simultaneous integrated) boost or the combination with new compounds/systemic treatments may increase antitumor efficacy but also toxicity. Despite low evidence, RT for oligometastatic disease is becoming increasingly popular. The omission of axillary dissection in node-positive disease led to an escalation of regional RT. Studies are ongoing to test if any axillary treatment can be omitted and which oligometastatic patients do really benefit from RT. Besides technical improvements, the incorporation of molecular risk profiles and also the response to neoadjuvant systemic therapy have the potential to optimize the decision-making concerning if and how local and/or regional RT should be administered.

Preoperative Magnetic Resonance Guided Single-Dose Partial Breast Irradiation: 5-Year Results of the Prospective Single-Arm ABLATIVE Trial

PURPOSE

Preoperative partial breast irradiation (PBI) can increase accuracy of target volume definition and decrease irradiated volumes compared with postoperative PBI. In the ABLATIVE trial (NCT02316561), 15 of 36 patients achieved pathologic complete response 6 to 8 months after preoperative PBI and breast-conserving surgery (BCS). We now present the 5-year results.

METHODS AND MATERIALS

The ABLATIVE trial is a Dutch prospective cohort study conducted in 4 hospitals. Women aged ≥50 years with unifocal, nonlobular breast cancer, estrogen receptor-positive, HER2-negative, and a tumor negative sentinel node were treated between 2015 and 2018 with preoperative single-dose PBI followed by BCS after 6 or 8 months. The primary endpoint was pathologic complete response. Secondary endpoints were annually evaluated oncological outcomes, toxicity, cosmetic outcome (assessed by patients and physicians), and quality of life.

RESULTS

Thirty-six patients were treated with BCS 6 (n = 15) and 8 (n = 21) months following PBI. Median tumor size was 13 mm (IQR 9-16 mm). After a median follow-up of 5.5 years (IQR, 5.1-6.0), 2 (6%) patients had ipsilateral breast events and 2 (6%) distant metastases. The 5-year overall survival was 94% (95% CI, 87-100). The 5-year cumulative incidence of clinician-reported grade 1/2 breast fibrosis and breast discomfort/pain were 94%/6% and 75%/6%, respectively. The proportion of patients (very) satisfied with the cosmetic results was 89% at baseline and 78% at 5 years. Cosmetic results evaluated using the BCCT.core software were excellent or good in all patients. The 4-year median global quality of life score was 83 (IQR, 67-92), similar to baseline (83; IQR, 75-83; P = .42).

CONCLUSIONS

Preoperative single-dose PBI and BCS may be an oncologically safe treatment with mild late toxicity and no decline in cosmetic results and quality of life during 5 years of follow-up. This means that preoperative instead of standard postoperative irradiation has the potential to challenge the current clinical practice.

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.

Very accelerated partial breast irradiation in 1 or 2 days: Late toxicity and early oncological outcome of the GEC-ESTRO VAPBI cohort

PURPOSE

To analyze late toxicity after very accelerated partial breast irradiation (VAPBI) for low-risk breast cancer.

MATERIALS

Methods: In this retrospective, observational, international multicenter study (HDH F20220713143949), patients with low-risk breast cancer underwent lumpectomy + vAPBI (high-dose rate multicatheter interstitial brachytherapy-MIBT). VAPBI was performed with 4(4x6.2 Gy/2d), 3(3x7.45 Gy/2d) or 1 fraction (1x16Gy or 1x18Gy/1d). Primary endpoint was late toxicity. Secondary endpoints were cumulative incidence of breast cancer local relapse (LR) and distant metastatic relapse (DMR) and specific (SS) and overall (OS) survivals. Prognostic factors for late toxicity were analyzed.

RESULTS

From 01/2012 to 06/2022, 516 pts with early breast cancer were enrolled. Median follow-up was 44 months [95 %CI 39-46]. Median age was 71 years [40-100]. Median tumor size was 12 mm [1-35]. VAPBI delivered 1, 3 and 4 fractions for 205pts (39.7 %), 167pts (32.4 %) and 144pts (28 %) respectively. 221 late toxicity events were observed in 168pts (32.6 %) (Fibrosis, dyschromia, pain and telangiectasia). Grade 2 and 3 late toxicities were observed in 7.2 and 0.6 % respectively (no G4) with no difference between 1 and ≥ 2 treatment days. CTV > 50 cc (p = 0.007) and V150 > 40 % (p = 0.027) were prognostic factors for G ≥ 2 late toxicity. Four-year cumulative incidence rates of LR and DMR were 2 % [95 %CI 0-3] and 1 % [95 %CI 0-2] respectively.

CONCLUSIONS

VAPBI based on 1 or ≥ 2 days of MIBT represents an attractive de-escalation of irradiation approach for low-risk breast cancer. Late toxicity profile appears acceptable while early oncological outcome shows encouraging local control. Longer follow-up is warranted in order to confirm these preliminary results.

Revolutionizing the battle against locally advanced breast cancer: A comprehensive insight into neoadjuvant radiotherapy

Breast cancer (BC) constitutes one of the most pervasive malignancies affecting the female population. Despite progressive improvements in diagnostic and therapeutic technologies, leading to an increased detection of early stage BCs, locally advanced breast cancer (LABC) persists as a significant clinical challenge. Owing to its poor overall survival (OS) rate, elevated recurrence rate, and high potential for distant metastasis, LABC prominently impacts the comprehensive efficacy of BC treatments. Radiotherapy, encompassing preoperative, intraoperative, and postoperative modalities, is acknowledged as an effective strategy for mitigating BC metastasis and enhancing survival rates among patients. Nevertheless, the domain of preoperative neoadjuvant radiotherapy (NART) remains conspicuously underexplored in clinical studies. Available research suggests that NART can induce tumor volume reduction, provoke fibrotic changes in tumor and adjacent normal tissues, thereby mitigating intraoperative cancer propagation and enhancing the quality of life for LABC patients. This manuscript seeks to provide a review of contemporary research pertaining to LABC and its preoperative radiotherapy.

Anti-Tumor Immunity and Preoperative Radiovaccination: Emerging New Concepts in the Treatment of Breast Cancer

Neoadjuvant chemotherapy (NACT) for certain breast cancer (BC) subtypes confers significant tumor regression rates and a survival benefit for patients with a complete pathologic response. Clinical and preclinical studies have demonstrated that immune-related factors are responsible for better treatment outcomes, and thus, neoadjuvant immunotherapy (IO) has emerged as a means to further improve patient survival rates. Innate immunological "coldness", however, of specific BC subtypes, especially of the luminal ones, due to their immunosuppressive tumor microenvironment, hinders the efficacy of immune checkpoint inhibitors. Treatment policies aiming to reverse this immunological inertia are, therefore, needed. Moreover, radiotherapy (RT) has been proven to have a significant interplay with the immune system and promote anti-tumor immunity. This "radiovaccination" effect could be exploited in the neoadjuvant setting of BC and significantly enhance the effects of the already established clinical practice. Modern stereotactic irradiation techniques directed to the primary tumor and involved lymph nodes may prove important for the RT-NACT-IO combination. In this review, we provide an overview and critically discuss the biological rationale, clinical experience, and ongoing research underlying the interplay between neoadjuvant chemotherapy, anti-tumor immune response, and the emerging role of RT as a preoperative adjunct with immunological therapeutic implications in BC.