FACTORS AFFECTING IDENTIFICATION OF SENTINEL LYMPH NODES IN BREAST CANCER PATIENTS USING METHYLENE BLUE DYE: A COMPARATIVE ANALYSIS

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Background: Sentinel lymph node biopsy (SLNB) is an integral procedure for staging axillary lymph nodes in breast cancer patients, traditionally performed using a combination of radioactive tracers and blue dye. However, in low- and middle-income countries (LMICs), the exclusive use of methylene blue (MB) dye is more common due to limited resources. This study aimed to evaluate the factors contributing to failure in identifying an adequate number of sentinel lymph nodes (SLNs) during SLNB with MB dye in breast cancer patients. Objective: To identify patient, tumor, and procedural factors associated with inadequate SLN identification (<3 nodes) using MB dye exclusively in SLNB for breast cancer patients. Methods: A prospective observational study was conducted from 2022 to 2024 at the Sindh Institute of Urology and Transplantation, Karachi. A total of 108 breast cancer patients undergoing SLNB were included and divided into cases (<3 SLNs identified) and controls (≥3 SLNs identified). Patient demographics, tumor characteristics, and procedural details were collected. Statistical analyses, including univariate and multivariate models, were performed using SPSS version 22.0. Key variables such as tumor size, breast cup size, tumor location, massage duration, and histopathological findings were analyzed. Results: Among 108 patients, 57 (52.8%) were cases and 51 (47.2%) were controls. Larger breast size (cup size ≥C, p=0.005), retro-areolar tumor extension (p=0.01), and right-sided tumors (p=0.001) were significantly associated with SLN identification failure. Shorter massage duration (8.6 vs. 9.49 minutes, p=0.008) and H2N-negative status (p=0.032) were also linked to poor outcomes. Histopathological factors such as tumor grade and hormone receptor status were not significantly associated. Patients receiving neoadjuvant chemotherapy showed a non-significant trend toward reduced SLN identification (p=0.153). Conclusion: This study highlights critical patient, tumor, and procedural factors influencing SLN identification with MB dye. These findings underline the need for tailored surgical techniques and alternative mapping strategies to optimize SLNB in resource-constrained settings.