ASCO has released a clinical practice guideline update on the role of sentinel lymph node biopsy (SLNB) in early-stage breast cancer.1 The update includes recommendations based on findings from trials released after the published guideline in 2017, including data from nine randomized trials comparing SLNB alone against SLNB with complete axillary lymph node dissection (ALND) and two trials comparing SLNB against no axillary surgery.2
“Several decades ago, we felt that we needed to know whether any of the lymph nodes within the axilla were involved with the cancer, and, to do that, we believed we had to do an aggressive surgery to remove at least 10 lymph nodes,” said Guideline Co-Chair Mylin A. Torres, MD, of Winship Cancer Institute, Emory University, explaining the evolution of ALND. “We quickly realized that was not without effect, with high rates of lymphedema, arm pain, and shoulder mobility issues that impact the quality of life of many women, sometimes for no reason when nodes were found to be negative.”
Mylin A. Torres, MD
Use of widespread ALND evolved into the use of SLNB in patients who had clinically node-negative disease. “We found that de-escalating surgery to the axilla diminished rates of lymphedema and improved overall quality of life but did not impair or diminish cure or recurrence rates,” Dr. Torres said. “For a long time, it was felt that all patients with invasive breast cancer had to have SLNB because it was required to accurately assess lymph node involvement, and this information is critical for determining appropriate adjuvant treatments.”
Omission of SLNB
The clinical practice guideline update recommends that clinicians not prescribe routine SLNB in select patients who are postmenopausal, aged 50 or older, and have negative findings on preoperative axillary ultrasound for grade 1 to 2, small (≤ 2 cm), hormone receptor–positive, HER2-negative breast cancer and undergo breast-conserving therapy.1
This recommendation is based on the results of two clinical trials: SOUND and INSEMA.3,4 The phase III SOUND trial compared whether omission of axillary surgery was noninferior to SLNB in patients with small breast cancer who had negative findings on preoperative axillary ultrasound. The 5-year distant disease–free survival was similar between the two groups. The phase III INSEMA trial evaluated whether omission of axillary surgery was noninferior to SLNB in patients with clinically node-negative invasive breast cancer of ≤ 5 cm who were scheduled to undergo breast-conserving surgery. Evaluation of invasive disease–free survival showed that omission of axillary surgery was noninferior to SLNB.
Challenges With Implementation
“It is a major change in the field of locoregional therapy in breast cancer, and, like many major changes, I anticipate it will take some intentional effort to implement these findings,” said Guideline Co-Chair Ko Un Park, MD, of Brigham and Women’s Hospital, Dana-Farber Cancer Institute. “The reason being that when we take away the information of the SLNB, it may influence what the radiation oncologist and the medical oncologist do as far as radiation and systemic therapy planning.”
Ko Un Park, MD
However, the update said that clinicians should not alter radiation or systemic therapy recommendations because SLNB is omitted. The Expert Panel included additional information in the update on how radiation and systemic treatment decisions may be affected by omission of SLNB.1 This information was designed to help the multidisciplinary team think through some nuanced situations prior to surgery.
According to Dr. Park, another challenging aspect of SLNB omission is that the initial workup in the SOUND and INSEMA trials included axillary ultrasound, which is not a universal practice.3,4 “It also poses practical challenges, mainly with regard to what to do with the information, meaning when the exam did not signify anything suspicious in the underarm, but the ultrasound did,” Dr. Park said. “Now that we have this information, what do we do with it, especially if the biopsy of the ultrasound-detected lymph node indicates metastasis? We don’t have that clinical trial data yet.”
Other important recommendations in the update include omission of ALND in patients with clinically node-negative invasive breast cancer of ≤ 5 cm who received mastectomy, have one to two positive sentinel nodes, and receive postmastectomy and regional nodal irradiation.1 This recommendation was supported in part by data from the SENOMAC trial, which showed no improvement in 5-year survival in patients who underwent ALND.5,6
Both Dr. Torres and Dr. Park acknowledged that recommendations related to the use or omission of SLNB and ALND will likely continue to evolve in the coming years. “More and more studies are going to show even more subsets of patients for whom SLNB can be omitted,” Dr. Torres said. “As imaging improves, we will be able to tell with greater certainty whether a node is involved with cancer or not, and I suspect there will be less need for performing SLNB.”
In breast cancer, Dr. Park added, when one arm of a multimodality therapy changes—whether that is surgery, radiation, or systemic therapy—it is apparent that clinical trials supporting this change only tested one particular modality. “It didn’t test whether we can omit SLNB and do less radiation therapy and less endocrine therapy, for example,” Dr. Park said. “As the field continues to evolve to more personalized treatment, we have to be thoughtful about how de-escalation of therapy fits into the grand scheme of things. This will be an ongoing area of research and will require multidisciplinary effort in the future to answer those questions.”
REFERENCES
1. Park KU, Somerfield MR, Anne N, et al: Sentinel lymph node biopsy in early-stage breast cancer: ASCO guideline update. J Clin Oncol. April 10, 2025 (early release online).
2. Lyman GH, Somerfield MR, Bosserman LD, et al: Sentinel lymph node biopsy for patients with early-stage breast cancer: American Society of Clinical Oncology clinical practice guideline update. J Clin Oncol 35:561-564, 2017.
3. Gentilini OD, Botteri E, Sangalli C, et al: Sentinel lymph node biopsy vs no axillary surgery in patients with small breast cancer and negative results on ultrasonography of axillary lymph nodes: The SOUND randomized clinical trial. JAMA Oncol 9:1557-1564, 2023.
4. Reimer T, Stachs A, Veselinovic K, et al: Axillary surgery in breast cancer: Primary results of the INSEMA trial. N Engl J Med 392:1051-1064, 2025.
5. de Boniface J, Tvedskov TF, Rydén L, et al: Omitting axillary dissection in breast cancer with sentinel-node metastases. N Engl J Med 390:1163-1175, 2024.
6. de Boniface J, Appelgren M, Szulkin R, et al: Completion axillary lymph node dissection for the identification of pN2-3 status as an indication for adjuvant CDK4/6 inhibitor treatment: A post-hoc analysis of the randomised, phase 3 SENOMAC trial. Lancet Oncol 25:1222-1230, 2024.
Originally published in ASCO Daily News. © American Society of Clinical Oncology. ASCO Daily News, April 10, 2025. All rights reserved.
