Axillary management in T1-3N1M0 breast cancer patients with needle biopsy proven nodal metastases at presentation after neoadjuvant chemotherapy (ATNEC).

ATNEC is a multicentre, phase III, randomised trial investigating the role of axillary treatment in early stage (T1-3N1M0) breast cancer patients.

Breast cancer sometimes spreads to lymph glands in the axilla (armpit) through the body’s lymphatic system. Patients who have this type of cancer are referred for neoadjuvant chemotherapy to shrink the cancer cells before their surgery. Standard of care is to have neoadjuvant chemotherapy, followed by a breast cancer operation (either a lumpectomy to remove the cancerous lump, or a mastectomy to remove the breast) and further treatment to the axilla. Axillary treatment is either axillary lymph node dissection (ALND), to remove all lymph glands in the armpit, or axillary radiotherapy (ART).

However, treatment to the axilla damages lymphatic drainage from the arm and can cause life-long side effects such as lymphoedema, restricted shoulder movement, and pain or numbness in the arm and hand. These side effects interfere with daily activities, impair quality of life and are costly to the NHS in terms of rehabilitative treatments.

Neoadjuvant chemotherapy is very effective and can eradicate cancer in the lymph glands in the axilla in 40% to 70% of patients. Therefore, extensive axillary treatment may not be necessary in those patients, with no evidence of residual disease in the lymph glands.

ATNEC aims to address this question by comparing standard axillary treatment (ALND or ART) with no axillary treatment post-surgery.

1900 participants will be randomised (1:1) to either standard axillary treatment (ALND or ART), or no further axillary treatment.

• Disease-Free Survival (DFS); defined and calculated as the time from randomisation until the date of first event of either a loco-regional invasive breast cancer relapse, distant relapse, ipsilateral or contralateral new invasive primary breast cancer or death by any cause or the censor date.
• Lymphoedema is self-reported based on two items from the validated Lymphoedema and Breast Cancer Questionnaire (LBCQ) (arm “swelling now” and arm “heaviness in the past year”). These items have been shown to be predictive of arm swelling of a 2 cm or more change in arm circumference but provide a simpler patient-friendly measure which has been used in other studies. Lymphoedema will be defined as ‘yes’ to both questions at five years.

ATNEC has a planned recruitment period of 5 years from December 2020 to December 2025 and a minimum 5-year follow up period (study end date February 2030).

ATNEC is open to the addition of new sites and still accepting expressions of interest, contact the study team for more information.