Roundtable Dialogue: Exploring Breast Cancer Radiotherapy Strategies and Multidisciplinary Innovation

Hubei Association of Radiation Oncology Physicians 2025 Academic Conference

Editor’s Note: The 2025 Annual Academic Conference of the Radiation Oncology Physicians Branch of the Hubei Medical Association was recently held in Wuhan. Organized by the Hubei Medical Association and hosted by Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, the event drew wide attention and participation from experts across the field of radiation oncology. Of particular note was the breast cancer session, which featured cutting-edge research and clinical insights. Oncology Frontier invited Professors Na Zhang (Liaoning Cancer Hospital), Chunling Jiang (Jiangxi Cancer Hospital), Yirui Zhai (Cancer Hospital, Chinese Academy of Medical Sciences), and Minghua Ji (Jiangsu Cancer Hospital) to engage in an in-depth discussion on topics including proton therapy in breast cancer, post-operative radiotherapy, and the integration of multidisciplinary care models—bringing forth new perspectives in the treatment of breast cancer.

Oncology Frontier: Compared to conventional radiotherapy techniques, what are the significant clinical advantages of proton therapy in breast cancer?

Professor Na Zhang: Proton therapy is a precise, efficient, and low-toxicity form of radiotherapy. Unlike traditional photon therapy, proton therapy leverages the unique physical property known as the “Bragg peak,” which enables high-dose radiation to be concentrated precisely within the tumor target zone. This results in enhanced therapeutic efficacy while significantly reducing radiation exposure to surrounding healthy tissues and organs, thereby minimizing side effects. Additionally, the treatment course tends to be shorter and requires fewer sessions, offering greater convenience for patients.

Oncology Frontier: How do you view the future direction of proton therapy in breast cancer treatment? In your opinion, which patient populations and clinical scenarios are most suitable for this approach?

Professor Na Zhang: Proton therapy demonstrates excellent dosimetric characteristics. However, its broader adoption is currently limited by high costs and limited accessibility. Another challenge lies in the uncertainties surrounding its radiobiological modeling and range variations during treatment, which are influenced by multiple factors. As a result, proton therapy requires stricter dose constraints than photon therapy.

For breast cancer patients, proton therapy is particularly advisable in specific scenarios. These include left-sided breast cancer cases where photon therapy cannot meet the safety thresholds for critical organs—especially when combined with cardiotoxic systemic therapies; patients at high risk of developing second primary malignancies; and those with long life expectancy who may require re-irradiation in the future.

Looking ahead, the combination of proton therapy with novel anti-tumor agents such as immunotherapy holds great promise. Such integrated approaches may profoundly impact patient outcomes and lead to more favorable long-term results.

Oncology Frontier: In your view, what role will proton therapy play in the future of comprehensive breast cancer treatment?

Professor Na Zhang: Radiotherapy remains one of the most important local treatment modalities in the comprehensive management of breast cancer. As a cutting-edge technique in the field, proton therapy—thanks to its distinct therapeutic advantages—is poised to play an increasingly vital role in future breast cancer care. We look forward to more prospective studies, randomized controlled trials (RCTs), and large-scale real-world evidence to provide higher levels of clinical validation for proton therapy. These data will be key in advancing the precision of breast cancer radiotherapy and driving a qualitative leap in treatment standards.

Oncology Frontier: Could you share with us the latest developments in breast cancer radiotherapy presented at the 2025 ASCO Annual Meeting?

Professor Chunling Jiang: Overall, while the number of studies on breast cancer radiotherapy presented at the 2025 ASCO Annual Meeting was relatively limited, they clearly reflected a growing trend toward precision de-escalation. The focus of most current research is on how to reduce the intensity of treatment without compromising efficacy, ultimately aiming to improve patients’ quality of life. I’d like to highlight four key studies that exemplify this direction.

Study 1

NRG-BR007 (Abstract No. TPS625) — De-escalating Radiotherapy in Early-Stage Hormone Receptor-Positive Breast Cancer

This study focuses on safely omitting radiotherapy in patients with low-risk, early-stage, hormone receptor-positive (HR+) breast cancer after breast-conserving surgery (BCS), guided by genomic profiling. Eligible participants are women aged 50–59 with T1N0 disease and an Oncotype DX Recurrence Score (RS) <18 or classified as low-risk by MammaPrint. The core hypothesis is that for ER/PR-positive, HER2-negative, stage I breast cancer patients with RS <18, BCS alone—followed by standard endocrine therapy—will provide non-inferior outcomes in terms of in-breast recurrence (IBR) control compared to BCS plus radiotherapy. As of May 2025, over 1,200 patients have been enrolled. The study aspires to establish a safe pathway for select early-stage HR+ patients to forgo radiotherapy, reducing treatment burden while maintaining therapeutic efficacy.

Study 2

NRG-BR008 (Abstract No. TPS1120) — Local De-escalation of Radiotherapy in Early-Stage HER2-Positive Breast Cancer

This study addresses a key clinical question: in the era of highly effective systemic therapy, is radiotherapy still necessary for low-risk HER2-positive breast cancer? The trial includes HER2-positive invasive breast cancer patients, divided into two cohorts:

Adjuvant cohort: T1-2 (≤3 cm), N0 patients who undergo upfront surgery
Neoadjuvant cohort: T <5 cm, N0 (clinically staged) patients who receive upfront anti-HER2 therapy

Participants are randomized into two arms:

Arm 1: Breast radiotherapy + continued HER2-targeted therapy ± hormone therapy (if indicated)
Arm 2: Omission of radiotherapy + continued HER2-targeted therapy ± hormone therapy

The primary endpoint is recurrence-free interval (RFI), comparing the outcomes of patients who receive radiotherapy versus those who do not. The trial is ongoing, and results are anticipated to clarify whether radiotherapy can be safely omitted in this subgroup.

Study 3

Surgery De-escalation After Neoadjuvant Chemoradiation in Triple-Negative/HER2-Positive Breast Cancer (Abstract No. TPS630)

This study evaluates whether surgery can be safely omitted in patients with triple-negative or HER2-positive breast cancer who achieve a pathological complete response (pCR) after neoadjuvant chemoradiotherapy, as confirmed by vacuum-assisted core biopsy (VACB). The primary endpoint is the 5-year event-free survival (EFS) of patients who skip surgery versus those who undergo standard procedures. To date, four patients have been enrolled. The investigators hope this study will pave the way for less invasive treatment strategies in highly responsive patients, significantly reducing the treatment burden for those who achieve pCR.

Study 4

Does Combining Antibody–Drug Conjugates (ADCs) with Radiotherapy Increase the Risk of Symptomatic Radiation Necrosis (SRN)? (Abstract No. 1039)

Radiotherapy remains a standard treatment for patients with brain metastases. This study investigated whether combining ADCs with radiotherapy elevates the risk of symptomatic radiation necrosis (SRN). Through a meta-analysis, researchers compared the risk of SRN between two patient groups:

Concurrent ADC group (C-ADC): patients receiving ADCs and radiotherapy simultaneously
Non-concurrent ADC group (NC-ADC): patients receiving ADCs and radiotherapy in a staggered manner

Data were sourced from PubMed and other databases. The analysis showed that the concurrent use of ADCs and radiotherapy significantly increased the risk of SRN—nearly tripling it—compared to non-concurrent treatment (19.5% vs. 6.9%; RR: 0.73; 95% CI: 1.45–5.11; P = 0.002). These findings raise important concerns about the safety of combining brain radiotherapy with ADCs in the current era of targeted therapies.

Oncology Frontier: In your opinion, what are the current research hotspots in post-operative radiotherapy for breast cancer? How do these research directions guide clinical practice?

Professor Yirui Zhai: There are three major focal points in the current research on post-operative radiotherapy for breast cancer:

1. Identifying the Appropriate Patient Population for Post-operative Radiotherapy It is crucial to accurately define which patients truly benefit from radiotherapy after surgery. With better patient stratification, those likely to benefit can receive effective treatment that enhances both survival and quality of life, while those unlikely to benefit—or who might experience significant side effects—can be spared unnecessary treatment. Previous studies, including those presented at international and domestic radiation oncology conferences, have explored whether elderly patients with early-stage disease can safely omit post-operative radiotherapy. This remains an important direction for future research.

2. Defining the Radiotherapy Target Volume A major debate centers around whether the internal mammary lymph node (IMLN) region should be included in the radiation field. Some studies suggest that radiating this area reduces the risk of local recurrence, while others indicate that it does not significantly improve overall survival. To address this uncertainty, the Cancer Hospital of the Chinese Academy of Medical Sciences has initiated the first large-scale, multicenter randomized controlled trial in China focusing on IMLN radiotherapy. If the study confirms its necessity, it will provide strong evidence to support expanding the radiation field. Conversely, if it proves unnecessary, it would allow clinicians to reduce radiation exposure and related toxicity. Moreover, it could help further clarify which subgroups of patients truly benefit from radiation and which do not.

3. Optimizing Radiotherapy Delivery Methods Breast tumors are characterized by a relatively low α/β ratio in radiobiological terms, making them well-suited for hypofractionated radiotherapy (larger doses per session over fewer sessions). Breast and prostate cancers have long been considered ideal candidates for this approach. Currently, there is a global trend toward further shortening radiotherapy courses—reducing treatments to as few as five sessions, each with a higher dose. This has significant advantages: it can lower patients’ direct healthcare costs (as charges are often based on session count) and reduce the overall financial burden, particularly for patients who must travel or stay near treatment centers. If future clinical practice confirms that hypofractionation provides equivalent outcomes for Chinese patients, this strategy could benefit a broader patient population by making treatment more accessible and less burdensome.

Oncology Frontier: Based on your clinical experience, what key factors should be considered when developing individualized post-operative radiotherapy plans for breast cancer patients?

Professor Yirui Zhai: Personalizing post-operative radiotherapy for breast cancer is a critical component of clinical decision-making. Although standardized treatment based on clinical guidelines has been widely promoted, the reality is that patient needs vary significantly. Therefore, individualized planning is indispensable.

In clinical practice, we typically take the following factors into account:

1. Age Age plays a crucial role in treatment planning, as patients at different life stages have different priorities. For example, a 40-year-old woman may prioritize long-term quality of life, cosmetic outcomes, and minimizing recurrence risk while maintaining survival benefits. In contrast, a 70-year-old woman, who may have a more limited life expectancy, might place greater value on preserving her current quality of life and minimizing treatment-related burdens.

2. Disease Stage Treatment strategies must be aligned with the patient’s cancer stage. Staging is a fundamental determinant of the appropriate therapeutic approach, and different stages require different radiotherapy strategies.

3. Patient Communication For patients who fall into a “gray zone”—such as those with intermediate risk, for whom radiotherapy may or may not be necessary—it is essential to engage in thorough discussions. We explain the patient’s risk of recurrence, the potential benefits of radiotherapy, and the consequences of opting out of treatment. At the same time, we take into account the patient’s personal values and preferences. Some patients may prioritize longer survival and reduced recurrence, while others may place more emphasis on maintaining quality of life and avoiding side effects. These individualized considerations are central to developing a patient-centered treatment plan.

Oncology Frontier: In the treatment of early-stage breast cancer, how do you view the role of radiotherapy within the multidisciplinary team (MDT) model?

Professor Minghua Ji: In early-stage breast cancer, treatment is primarily surgical and multidisciplinary, while in advanced disease, internal medicine and systemic therapy take the lead. Radiotherapy plays an important and effective role in both early and late stages of breast cancer.

For early-stage patients, local treatment strategies now encompass breast-conserving surgery (BCS), breast reconstruction, and axillary lymph node management. Radiotherapy has become an increasingly vital component of these treatment plans. Hypofractionated radiotherapy is gaining widespread clinical acceptance for patients following breast-conserving surgery, with moderate-dose hypofractionation now commonly used. For selected low-risk patients, ultra-hypofractionation (even fewer treatment sessions with higher doses per session) has also emerged as a feasible option.

One of the current hotspots in early-stage breast cancer radiotherapy is whether elderly patients can safely omit radiation therapy. This topic remains a point of ongoing discussion. If effective outcomes can be achieved by omitting radiotherapy and combining systemic therapies in certain subgroups, patient acceptance and adherence to treatment are likely to improve significantly.

Regarding axillary lymph node management, for early-stage patients with low axillary tumor burden, radiotherapy may allow some patients to avoid axillary lymph node dissection (ALND). Several studies have already provided evidence supporting this approach, showing that radiotherapy can be effective in managing nodal involvement while sparing patients from the potential morbidity of surgery.

Oncology Frontier: As a radiation oncologist, how do you collaborate with other departments—such as surgery and medical oncology—within the MDT team, and what challenges have you encountered?

Professor Minghua Ji: The multidisciplinary team (MDT) model has now been widely adopted in hospitals and plays a crucial role in cancer treatment. Besides surgical and medical oncologists, MDTs also include specialists from radiation oncology, radiology, pathology, and other departments. However, in most cases, radiation oncology plays a supportive role within the team. Of course, there are exceptions—such as in nasopharyngeal carcinoma, where radiotherapy may be the primary treatment modality—but in breast cancer, radiation typically remains an adjunctive treatment.

As radiation oncologists, we must take the initiative to communicate effectively with our colleagues in surgery and medical oncology. It’s essential to keep them informed about the latest advancements in radiotherapy for breast cancer. This ensures that patients who require radiotherapy can receive it in a timely manner, while those who may safely omit it can avoid unnecessary treatment. Such coordination not only improves treatment outcomes but also promotes more standardized and evidence-based care.