Research Summary

2025 ASCO Guidelines Support Omission of Sentinel Lymph Node Biopsy in Select Early-Stage Breast Cancers

Anthony Calabro, MA

Key Highlights

  • Sentinel lymph node biopsy (SLNB) can be safely omitted in select postmenopausal patients ≥ 50 years with small, low-grade, hormone receptor–positive, HER2-negative tumors.
  • Omission of SLNB does not compromise cancer control, survival outcomes, or systemic therapy decisions.
  • Trials show omitting SLNB reduces postoperative complications, including arm dysfunction and lymphedema.
  • Radiation and chemotherapy recommendations remain consistent for eligible patients, emphasizing shared decision-making.

In June 2025, the American Society of Clinical Oncology (ASCO) issued an updated guideline on sentinel lymph node biopsy (SLNB) for patients with early-stage breast cancer undergoing up-front breast-conserving surgery. The update reflects growing evidence that SLNB may be safely omitted in select low-risk cases without compromising outcomes. The recommendations, presented through detailed clinical algorithms, aim to balance the benefits of accurate staging with the potential harms of surgical intervention.

Historically, SLNB provided local-regional control and informed adjuvant therapy decisions. However, large clinical trials—including SOUND (Sentinel Node vs Observation After Axillary Ultra-Sound) and INSEMA (Intergroup Sentinel Mamma)—demonstrated no survival advantage to performing SLNB in appropriately selected patients. The updated guideline responds to this paradigm shift by aiming to reduce surgical morbidity such as pain, wound infection, axillary cording, and lymphedema, which persist even after minimally invasive procedures. Studies cited in the ASCO updated guideline show that 22% of patients reported significant arm dysfunction shortly after SLNB, with 13% experiencing persistent issues at 1 year.

The guideline recommends SLNB omission for postmenopausal women aged 50 years or older with unifocal, ≤ 2-cm, grade 1–2, hormone receptor–positive, HER2-negative invasive ductal carcinoma, and negative axillary ultrasound findings who are planning breast-conserving surgery and adjuvant endocrine therapy. For patients 65 years of age or older meeting these criteria, whole-breast radiation may also be omitted. Conversely, axillary lymph node dissection is not indicated for patients with one or two positive sentinel nodes who will receive breast-conserving surgery and whole-breast radiotherapy. These recommendations reflect an emphasis on individualized treatment planning and avoidance of overtreatment.

The SOUND and INSEMA trials also informed updates to radiation and systemic therapy decision-making. Radiation oncologists are advised not to alter treatment based on SLNB omission in eligible patients, as incidental axillary radiation within tangential fields provides adequate local control. Furthermore, genomic assays such as the 21-gene recurrence score can guide adjuvant chemotherapy decisions even when SLNB is omitted, especially in postmenopausal patients with hormone receptor–positive, HER2-negative disease. The guideline underscores that omission of SLNB does not affect systemic therapy decisions or outcomes in this population.

“Decision-making for optimal therapy should balance risk of cancer recurrence, morbidity of treatment, patient preferences (including risk aversion versus tolerance), and multidisciplinary clinicians’ input,” the guideline authors concluded.

Reference
Park KU, Mailhot Vega RB, Shams S, et al. Sentinel lymph node biopsy in early-stage breast cancer: ASCO guideline clinical insights. JCO Oncol Pract. 2025;00:1-7. doi:10.1200/OP-25-00447.