What is the primary clinical benefit of replacing routine axillary lymph node (ALND) dissection with sentinel lymph node (SLN) biopsy?

Primary Clinical Benefit of Sentinel Lymph Node Biopsy

The primary clinical benefit of replacing routine axillary lymph node dissection with sentinel node biopsy is the dramatically lower incidence of lymphedema and shoulder dysfunction, with lymphedema rates of approximately 2.6-3.6% after SLNB compared to 17-27% after ALND, while maintaining equivalent survival outcomes. 1, 2

Morbidity Reduction: The Core Advantage

The evidence unequivocally demonstrates that SLNB provides substantial reduction in arm and shoulder morbidity compared to ALND:

• Lymphedema rates are reduced from 27% with ALND to 2.6% with SLNB alone 2, 3
• Shoulder dysfunction including reduced arm strength, mobility, and range of motion occurs significantly less frequently with SLNB 1, 4
• Sensory deficits and paresthesia are markedly reduced, with risk ratios showing 74% less paresthesia with SLNB (RR 0.26,95% CI 0.20-0.33) 5
• Pain and seroma formation occur less frequently after SLNB 1

Quality of Life Impact

Multiple randomized controlled trials confirm superior quality of life outcomes with SLNB:

• Patients treated with SLNB score significantly better on both subjective criteria (perceived arm strength, mobility, swelling, pain) and objective measurements (measured arm strength, mobility, lymphedema, sensitivity) 4
• The AMAROS trial demonstrated higher lymphedema rates in the ALND group compared to alternative approaches at 10-year follow-up 1
• Physical and psychological morbidity are both reduced with SLNB 1

Survival Equivalence: No Compromise in Oncologic Outcomes

Critically, this morbidity reduction comes without any sacrifice in survival or disease control 1:

• The ACOSOG Z0011 trial showed 10-year overall survival was noninferior between SLNB alone versus ALND in patients with 1-2 positive sentinel nodes 2
• Multiple trials including SINODAR-ONE and SENOMAC confirmed no differences in overall survival, disease-free survival, or regional recurrence rates 1
• A meta-analysis of 130,575 patients found no significant differences in overall survival (HR 0.95% CI 0.85-1.06), disease-free survival (HR 1.00,95% CI 0.98-1.02), or locoregional recurrence (RR 0.92,95% CI 0.59-1.44) 5

Why Other Options Are Incorrect

Cosmetic outcome (Option A): SLNB affects the axilla, not breast appearance. Cosmetic outcomes relate to breast surgery type (lumpectomy vs mastectomy), not axillary staging method 1

Survival improvement (Option C): Multiple high-quality trials definitively show SLNB provides equivalent survival to ALND, not improved survival. The benefit is reduced morbidity with maintained survival 1, 5

Reduced chemotherapy need (Option D): Systemic therapy decisions are based on tumor biology (hormone receptors, HER2 status, grade, proliferation markers) and nodal status, not the surgical technique used for axillary staging. SLNB provides accurate staging information but doesn't change chemotherapy indications 1

Clinical Context

The anatomic disruption from ALND—removing 10-30 lymph nodes and disrupting lymphatic channels—directly causes the high morbidity rates 1. SLNB removes only 1-3 nodes, preserving lymphatic drainage and avoiding nerve injury that causes shoulder dysfunction 2. This represents a fundamental shift in breast cancer surgery: achieving the same staging accuracy and survival outcomes while dramatically improving patient quality of life 1, 4.

Answer: B. Lower incidence of lymphedema and shoulder dysfunction