Risk Factors Associated With Sentinel Lymph Node Metastasis in Clinically Node-Negative Breast Cancer.

Objective: Sentinel lymph node biopsy (SLNB) is the standard of care for axillary staging in clinically node negative breast cancer. If predictive factors for sentinel lymph node (SLN) metastasis could be identified, it would allow selection of candidates for SLNB and omit axillary surgery in those with the lowest risk of axillary lymph node involvement. The aim of this study was to determine risk factors associated with SLN metastasis in breast cancer patients in Bahrain.

Materials and methods: Patients with clinically node-negative breast cancer who underwent SLNB at a single institution between 2016 and 2022 were identified from the pathology database. Patients who had failure of localization of SLN, those with bilateral cancers and those treated for a local recurrence were excluded.

Results: A total of 160 breast cancer patients were retrospectively analyzed. Of these, 64.4% had a negative SLNB and 21.9% of all cases underwent axillary dissection. The following parameters emerged as predictors of SLN metastasis in univariate analysis: age; tumour grade; ER status; presence of lymphovascular invasion (LVI) and tumor size. On multivariate analysis, age was not independently associated with the incidence of SLN metastasis.

Conclusion: This study showed that high tumour grades, presence of LVI and large tumour size were all risk factors related to axillary metastasis after SLNB in breast cancer. In the elderly, the incidence of SLN metastasis appeared to be relatively low, providing an opportunity to de-escalate axillary surgery in these patients. These findings may allow for the development of a nomogram to estimate the risk of SLN metastasis.