Breast cancer is the most common cancer worldwide and continues to contribute significantly to global cancer mortality and morbidity. Surgical management of the axilla plays a crucial role in treating breast cancer. Over the past several decades, breast cancer treatment has evolved significantly, transitioning from routine radical mastectomy with axillary lymph node dissection (ALND) for all patients to a more individualized surgical approach.

Historically, ALND was performed in all cases to remove the entire locoregional tumor burden, with the belief that this would improve survival. However, this approach has been challenged, as ALND carries significant morbidity, notably arm lymphedema, which affects one in five breast cancer survivors and has a considerable negative psychosocial impact.

To reduce this morbidity, neoadjuvant chemotherapy (NACT) has been shown to downstage axillary disease, allowing for the de-escalation of axillary surgery from extensive procedures like ALND to less invasive ones like sentinel lymph node biopsy (SLNB), thereby minimizing complications.

Over the last decade, evidence from various retrospective studies has demonstrated that SLNB alone does not increase axillary recurrence rates (ARR) or worsen disease-free survival (DFS) or overall survival (OS) compared to ALND in patients with clinically node-positive (cN+) disease rendered node-negative (cN0) after NACT. However, most of these studies have been conducted in Western populations, with small sample sizes, retrospective designs, and relatively short-term outcomes.

Emerging evidence suggests that ALND can be safely avoided and replaced with SLNB in this subset of patients without affecting ARR, DFS, or OS, while significantly reducing the risk of lymphedema. However, there is a lack of data regarding the outcomes of this approach in Indian breast cancer patients.

We hypothesize that in breast cancer patients with axillary nodal metastases (cT1-3N1-2M0) who are rendered cN0 by NACT, SLNB (intervention) compared to ALND (control) will reduce the risk of arm lymphedema without increasing cancer recurrence at a one-year follow-up.