ADARNAT Pilot Study: Radiotherapy Shows Promise in Reducing Lymphoedema After Breast Cancer Surgery
Patients with breast cancer undergoing surgery to remove lymph nodes in the armpit (axilla) frequently face the risk of lymphoedema, an often painful swelling. New findings from a pilot study offer hope, suggesting that axillary radiotherapy (ART) could be an alternative to axillary lymph node dissection (ALND). This approach potentially reduces the risk of lymphoedema while effectively targeting remaining cancer cells.
The ADARNAT Trial: Pilot Phase Insights
The findings emerge from the pilot phase of the ADARNAT trial, a phase III randomized international clinical trial. This study investigates whether axillary radiotherapy (ART) presents a lower risk of lymphoedema compared to axillary lymph node dissection (ALND). The focus is on breast cancer patients who received neoadjuvant systemic therapy (such as chemotherapy or hormone therapy) before surgery and had cancer spread to only one or two lymph nodes. The trial also evaluates overall and disease-free survival rates.
Professor Amparo Garcia-Tejedor, from Bellvitge University Hospital, Spain, leads the ADARNAT trial. She highlighted that earlier studies have already established ART as an alternative to ALND for patients initially treated with surgery. The ADARNAT trial extends this crucial investigation to patients who underwent neoadjuvant therapy, a group often showing a significant reduction in axillary disease burden.
Between June 2021 and April 2023, 272 breast cancer patients with metastatic cancer in one or two sentinel lymph nodes after neoadjuvant therapy were recruited. Participants were randomized to receive either ART or ALND, with both groups also undergoing radiotherapy to breast and chest areas. Preliminary results are available for 46 ART patients and 56 ALND patients, with a median follow-up of two years.
Preliminary Findings: Efficacy and Side Effects
The pilot data showed promising cancer outcomes. No axillary cancer recurrence was observed in the ART group, whereas one recurrence (1.8%) was noted in the ALND group. Distant metastasis occurred in 4.4% of ART patients compared to 5.5% of ALND patients. Two deaths were reported in the ALND group (4.3%).
Regarding the primary concern, lymphoedema, it occurred more frequently after ALND (26.7%) than ART (18.9%). However, this observed difference was not statistically significant in the pilot phase. Disease-free and overall survival rates were similar across both groups after two years of follow-up.
Dr. Maria Laplana-Torres, a radiation oncologist, presented findings on side effects. Acute skin damage (grade 2 or above) was more prevalent in ART patients (27.8%) compared to ALND patients (13.3%). This damage, including redness, pigment changes, or skin peeling, was generally transient and manageable. No significant differences in later skin damage were observed between the two groups. Some ART patients also reported mild, temporary difficulties with arm mobility, though these did not impact daily activities.
Researcher Perspectives and Future Directions
Professor Garcia-Tejedor commented on the pilot results, stating: "These results indicate ART is feasible and yields good cancer outcomes at two years." She underscored that definitive results from the ongoing phase III trial are crucial before any changes to clinical practice can be considered. The trial's objective is to gather robust data to confirm the safety and effectiveness of ART, particularly for patients with residual axillary disease.
The main phase III clinical trial has already enrolled over 500 patients. Researchers project approximately three more years for patient recruitment, followed by a planned five years of follow-up to comprehensively assess cancer outcomes.
If the study ultimately confirms the safety and effectiveness of ART, it holds the potential to significantly improve patient quality of life by reducing lymphoedema and other functional complications often associated with axillary surgery. This could support a broader shift towards more personalized and less morbid treatment strategies.
Professor Isabel Rubio, Chair of EBCC15, remarked that these pilot findings are highly encouraging and strongly support the continuation of the clinical trial. The final results will be pivotal in determining the long-term safety of radiotherapy as an alternative to surgery for patients who have received neoadjuvant treatments. Future research, she noted, will also aim to identify patients who might safely omit both axillary dissection and radiation entirely, further minimizing treatment-related complications.