Incidence of a Positive Sentinel Lymph Node Biopsy in Screen-Detected Early Breast Cancer.

Introduction Current guidelines advocate for a sentinel lymph node biopsy (SLNB) in patients with invasive breast cancer with negative axillary ultrasonography. However, emerging evidence has contradicted this, and SLNB omission has been found to be non-inferior in selected low-risk breast cancers. This retrospective study aimed to evaluate the incidence of SLNB in screen-detected invasive breast cancer. The secondary outcome was to identify risk factors in patients with positive SLNB and further axillary disease. Methods All screen-detected histologically confirmed invasive breast cancer and no evidence of spread to ipsilateral axillary lymph nodes (LNs) on ultrasound scans referred from screening between January 2018 and December 2019 were included in the study. All patients underwent surgical excision of the tumor as either breast conservation surgery or mastectomy, along with sentinel node biopsy. SLNB was performed using the dual technique of radioactive dye and blue dye. Results One hundred forty-nine patients were included in the study, all of whom were females. The mean patient age was 61.9 years old, with the majority 65 (43.6%) of the patients being in their 60s. Breast-conserving surgery (BCS) was performed in 138 (92.6%) patients. Eighty (53.7%) patients presented with right breast cancer. The mean size of invasive cancer was 15 mm. The mean total tumor size, including invasive and in situ, was 20.9 mm. One hundred twenty-seven (85.2%) patients had unifocal presentations, 69 (46.3%) of tumor foci were in the upper outer quadrant (UOQ), 122 (81.9%) of all tumors were ductal carcinoma, 81 (54.4%) patients had histologically grade 2 carcinomas, 135 (90.6%) of all patient tumors were ER-positive, HER2-negative, and six (4%) were ER-positive, HER2-positive. Twelve (8.05%) out of 149 included patients had positive sentinel LN biopsy. Of those 12 patients, eight (66.7%) had one to two nodes sampled, three (25%) had three to four nodes, and one (8.3%) had five or more nodes sampled. Out of 12 positive SNB patients, 11 had completed axillary node clearance (ANC) as per the National Institute for Health and Care Excellence (NICE) guidelines: nine (81.8%) had no further disease, and two (18.2%) had four positive nodes. The mean number of nodes taken in ANC was 15.8 ± 11.5. Of the two patients with positive axillary disease, one had BCS, and the other had a mastectomy. Both were grade 3 IDC, and the mean size was 57.5 mm. Nine patients died within four years of diagnosis, with four due to distant breast metastasis. Conclusion Only 8% of patients had positive SLNB in screen-detected breast cancer, which may support the previous studies of omitting SLNB being non-inferior but only in selected postmenopausal small early breast cancers with normal axillary ultrasound in the absence of any other risk factors. However, close follow-up will be required for disease-free survival, overall survival, and locoregional recurrence in this cohort.