Applying the SOUND Trial for Omitting Axillary Surgery in Patients With Early Breast Cancer in Bahrain

The Sentinel Node vs. Observation After Axillary Ultra-Sound (SOUND) trial reported that omission of axillary surgery was not inferior to sentinel lymph node biopsy (SLNB) in those with cT1 breast cancer and negative preoperative axillary ultrasound. The aim of our study was to evaluate the clinical characteristics of early breast cancer patients undergoing breast conserving surgery (BCS) at our institution in order to investigate the exportability of SOUND criteria to our patient population.

We retrospectively reviewed patients with cT1N0 breast cancer undergoing BCS and adjuvant radiotherapy according to the SOUND trial criteria. Comparison was made between the eligible group of our cohort and the SLNB arm of the SOUND trial.

The proportion of younger patients was higher in our eligible cohort (37.7% vs. 17.5%, p = 0.002). Postmenopausal patients were more prevalent in the SOUND trial (79.4% vs. 56.6%, p = 0.004). On final pathology, tumours were more likely to be upgraded to T2 in our group (26.4% vs. 4.4%, p = 0.001). Patients in our cohort were more likely to receive adjuvant chemotherapy (37.7% vs. 20.1%, p = 0.002).

The clinicopathological differences between our cohort and the SOUND trial population could be attributed to aggressive tumours in Bahrain compared to Western countries. Our study may influence others to investigate the applicability of the SOUND trial in clinical practice. Nevertheless, it is a study that should generate multidisciplinary discussion in the de-escalation of axillary surgery.