Sentinel node occult lesion localization technique for impalpable breast cancer

Mammographic screening has enabled earlier detection of breast cancer, with 25-35% of malignancies being non-palpable at diagnosis. Accurate removal and sentinel node biopsy for staging these lesions are crucial to successful management. Both these aspects are achieved by peritumoural localization with radioisotope and lymphoscintigraphy for sentinel lymph node (SN) mapping using the sentinel node and occult lesion localization (SNOLL) technique. This study reports SNOLL outcomes in a large cohort of women with non-palpable breast cancers to assess its performance and promote its logistic advantages.

This retrospective cohort study used data from BreastSurgANZ Quality Audit supplemented with private case notes. Inclusion criteria were females >18 years, with invasive breast cancer that was asymptomatic and non-palpable at presentation, who underwent SNOLL (n = 450). Primary outcomes were proportion of successful lesion localization, proportion of patients requiring re-excision and volume of tissue excised. Secondary outcomes focused on lymphoscintigraphy success rate in detecting sentinel nodes and SN positivity rates.

Tumours were successfully removed with the initial SNOLL procedure in 449 cases (99.8%). The re-excision rate was 15.1% (n = 68). The mean total excision volume was 54.69 cm³ (95% CI 51.49-57.88 cm³ ; range 2.75-195.33 cm³ ), with a mean closest circumferential margin of 7.05 mm (95% CI 6.60-7.49 mm; range 0 to ≥10 mm). Lymphoscintigraphy was successful in 96.9% (n = 436) of cases. Sentinel nodes were successfully identified and removed in 99.6% (n = 448) of cases. SN positivity rate was 18.4%.

SNOLL is an efficient and effective technique for localizing non-palpable invasive breast lesions while simultaneously identifying sentinel nodes.