In a groundbreaking development presented at the recent 15th European Breast Cancer Conference in Barcelona, emerging evidence suggests that radiotherapy to the axilla might serve as a less invasive yet equally effective alternative to surgery for patients with breast cancer who have limited lymph node involvement after neoadjuvant therapy. This revelation stems from the pilot phase of the ADARNAT clinical trial, a randomized international study investigating the comparative outcomes of axillary radiotherapy (ART) versus axillary lymph node dissection (ALND) in this specific patient population.
Axillary lymph node dissection has long been the conventional approach for managing metastasis in regional lymph nodes, often involving the removal of numerous lymph nodes in the armpit to eliminate residual cancer and reduce recurrence risk. However, ALND is frequently associated with significant postoperative complications, most notably lymphoedema—a chronic and frequently debilitating swelling of the arm caused by lymphatic fluid accumulation due to disrupted lymphatic drainage. The prospect of radiotherapy as a substitute aims to mitigate these morbidity risks while maintaining oncological efficacy.
The ADARNAT trial concentrated on patients who had undergone neoadjuvant systemic therapies, such as chemotherapy or hormone therapy, prior to surgery. These treatments often reduce tumor size and eradicate metastasis in lymph nodes, leaving only a limited number of sentinel lymph nodes positive for cancer at the time of surgery. This specific subset—patients with one or two involved sentinel nodes post-neoadjuvant therapy—might not derive significant added benefit from extensive surgical removal of axillary nodes, which potentially subjects patients to unnecessary side effects.
Between mid-2021 and early 2023, the trial enrolled 272 patients diagnosed with breast cancer exhibiting metastasis in only one or two sentinel lymph nodes following systemic therapy. Participants were randomized to receive either axillary radiotherapy or conventional surgical dissection, with both groups receiving radiation to the breast and chest regions. The median follow-up period was two years, a critical window for assessing short-term oncologic safety and adverse effects.
Intriguingly, no axillary cancer recurrences were detected among patients treated with ART, whereas a single recurrence (about 1.8%) was identified in the ALND group. Rates of distant metastasis were comparable between the two cohorts—4.4% in the ART arm and 5.5% with ALND—further suggesting equivalency in systemic disease control. Mortality within this follow-up was low and slightly favored the ART group. Importantly, lymphoedema incidence, while not statistically significant, trended lower in patients receiving radiotherapy (18.9% versus 26.7% in the surgical arm), implying a clinical benefit in terms of reducing this common complication.
Beyond cancer control, the nature and severity of treatment-related toxicities form a crucial consideration. The study observed a higher frequency of acute skin reactions in the ART group, with 27.8% experiencing grade 2 or worse dermatitis compared to 13.3% following ALND. Manifestations included erythema, pigmentation changes, and peeling. However, these reactions were transient and manageable, and no significant long-term dermatologic differences were noted between groups.
Functional outcomes, specifically arm mobility, were also evaluated. Mild, transient impairments in arm elevation and lateral movement occurred slightly more often in ART patients but did not affect daily activities significantly. Measures of quality of life aligned closely between the arms, with a subtle trend favoring those receiving radiotherapy. These data collectively support the contention that axillary radiotherapy offers a feasible, less morbid alternative with qualitatively similar patient experience post-treatment.
Principal investigator Professor Amparo Garcia-Tejedor underscored the preliminary nature of these results, cautioning against hastily changing clinical practice prior to the completion of the full phase III trial. Yet, she indicated that these findings lay the foundational rationale for de-escalating axillary surgery in favor of radiotherapy, especially in patients demonstrating good response to neoadjuvant therapy.
Dr. Maria Laplana-Torres, radiation oncologist and trial co-presenter, emphasized the importance of this ongoing research in refining personalization of breast cancer care. The ability to tailor axillary treatment intensity based on individual disease burden promises to minimize adverse effects without compromising cancer outcomes. Such advances align with the broader movement toward more precise, patient-centered oncology protocols.
Looking ahead, the main phase III segment has already enrolled over 500 patients and aims for robust statistical power to definitively assess long-term survival, recurrence, and quality of life metrics over a planned five-year follow-up. If the final data mirror current trends, it could herald a substantive paradigm shift—encouraging clinicians to favor radiotherapy over surgery in selected populations, thereby sparing many women from the lifelong burden of lymphoedema and other surgical complications.
The chair of the conference, Professor Isabel Rubio, echoed the cautious optimism permeating the breast oncology community. She highlighted that while the pilot data encourage pursuit of less invasive alternatives, further stratification of patients to identify those who might safely omit both surgery and radiation is a promising frontier. Ultimately, such innovation could revolutionize axillary management, balancing oncologic safety with enhanced patient quality of life.
This evolving evidence base underscores the critical imperative of well-designed randomized controlled trials to delineate optimal treatment strategies in an era increasingly defined by precision medicine. The ADARNAT trial represents a significant step forward in understanding how to safely reduce the morbidity burden associated with breast cancer treatment without compromising the ultimate goal—eliminating cancer and prolonging survival.
Subject of Research: People
Image Credits: ADARNAT team
Keywords: Breast cancer, Breast carcinoma, Surgery, Cancer treatments, Radiation therapy, Surgical procedures, Personalized medicine, Side effects, Physical rehabilitation
