In a noninferiority phase III trial (SOUND) reported in JAMA Oncology, Gentilini et al found that no axillary surgery was noninferior to sentinel lymph node biopsy (SLNB) in terms of distant disease–free survival among patients with small breast cancer and negative findings on preoperative ultrasonography of axillary lymph nodes.
Study Details
The trial included 1,405 patients from sites in Italy, Switzerland, Spain, and Chile with breast tumors measuring ≤ 2 cm and a negative preoperative axillary ultrasonography result. Patients were randomly assigned between February 2012 and June 2017 to receive no axillary surgery (observation, n = 697) or SLNB (n = 708). Median tumor size was 1.1 cm (interquartile range [IQR] = 0.8–1.5 cm). Overall, 88% of patients had estrogen receptor–positive, HER2-nonoverexpressing disease. The primary endpoint of the trial was distant disease–free survival at 5 years in the intention-to-treat population. Noninferiority was considered shown if the upper limit of the two-sided 90% confidence interval for the hazard ratio for omission of axillary surgery vs SLNB at 5 years was less than 1.74.
Key Findings
Median follow-up was 5.7 years (interquartile range [IQR] = 5.0–6.6 years) with the omission of axillary surgery and 5.7 years (IQR = 5.0–6.8 years) with SLNB. Distant disease–free survival at 5 years was 98.0% with omission of axillary surgery vs 97.7% with SLNB (HR = 0.84, 90% CI = 0.45–1.54, P = .67; P = .02 for noninferiority).
During follow-up for the omission of axillary surgery group vs the SLNB group, locoregional relapse occurred in 11 patients (1.6%) vs 12 patients (1.7%); distant metastasis occurred in 14 (2.0%) vs 13 (1.8%); and death occurred in 18 (2.6%) vs 21 (3.0%). Axillary recurrence occurred in 0.4% of patients in each group.
The 5-year disease-free survival was 93.3% with the omission of axillary surgery vs 94.7% with SLNB (P = .30). Overall survival at 5 years was 98.4% vs 98.2 % (P = .72).
The investigators concluded: “In this randomized clinical trial, omission of axillary surgery was noninferior to SLNB in patients with small breast cancer and a negative result on ultrasonography of the axillary lymph nodes. These results suggest that patients with these features can be safely spared any axillary surgery whenever the lack of pathological information does not affect the postoperative treatment plan.”
Oreste Davide Gentilini, MD, of the European Institute of Oncology Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), is the corresponding author of the JAMA Oncology article.
Disclosure: For full disclosures of the study authors, visit jamanetwork.com.
