腋窩手術の省略：リンパPETと統合した術前腋窩評価を受けた患者を対象とした前向き臨床研究

Sentinel lymph node biopsy (SLNB) is the standard surgical approach for axillary node staging in patients with early-stage breast cancer (EBC). However, there is an increasing trend in investigating the omission of SLNB, as molecular tumor biology has become a primary determinant of systemic therapy, overshadowing the importance of nodal status.

The SOAPET trial constitutes a prospective phase II study structured into two phases. In the first stage, we demonstrated that LymphPET could be utilized to screen patients to potentially forego SLNB, achieving a negative predictive value of 91%. In the second stage, SLNB was omitted for patients with a negative preoperative axillary evaluation (PAE) integrated with LymphPET. Primary endpoints were the 3-year distant disease-free survival (DDFS) and locoregional recurrence-free survival (LRRFS).

A total of 304 patients were enrolled with a median age of 52.5 years (IQR 44-62 years). Of these patients, 240 (78.9%) presented with clinical T1 tumors. Among all the cases, 218 (71.7%) were classified as luminal-like breast cancer. The median follow-up was 43.5 months. The 3-year DDFS and LRRFS rates were 100% and 99.7% (95% CI 99.0-100.0), respectively. In the entire cohort, two cases (0.7%) of ipsilateral axillary node relapse, one (0.3%) ipsilateral in-breast recurrence, and one (0.3%) distant metastasis were reported.

The second phase of the study corroborates the oncologic safety of omitting SLNB on the basis of PAE incorporating LymphPET. For patients with clinically node-negative EBC with high-risk characteristics, SLNB might be safely spared with the added diagnostic benefit provided by LymphPET.

ClinicalTrials.Gov ID NCT04072653.