P165 Sentinel lymph node biopsy in primary cutaneous malignant melanoma: an 8-year real-world retrospective cohort study

Abstract Malignant melanoma is the fifth most common cancer in the USA and the UK, with rising incidence. Advances in early detection and systemic anticancer treatment (SACT) have improved patient outcomes. Identification of regional involvement through sentinel lymph node biopsy (SLNB) can provide important prognostic information, although it has associated risks. We report 8-year real-world evidence on melanoma management and SLNB outcomes from a UK tertiary dermatology centre. We identified 285 adult patients with primary cutaneous melanoma diagnosed between September 2015 and October 2023. Patient demographics, tumour characteristics and SLNB results were recorded from electronic records. Patients were staged using the American Joint Committee on Cancer 7th (up to 2018) and 8th editions. The patients’ average age was 64 years (range 17–98), with 179 patients (63%) diagnosed from face-to-face and 106 (37%) diagnosed from teledermatology consultations. No significant difference was observed in Breslow thickness for melanomas diagnosed in teledermatology or face-to-face consultations (P = 0.09). However, a significant reduction (P < 0.001) in mortality was noted for patients diagnosed from teledermatology (5%, n = 5) compared with face to face (23% n = 38). SLNB was considered in 126 eligible patients and was performed in 86 patients (24 declined, 12 unsuitable, 4 pending results), with 16 positive results. Patients referred for SLNB had a significantly higher mitotic rate (4 vs. 2, P < 0.005), as well as higher rate of ulceration (30 vs. 14, P < 0.05), but lower incidence of regression (P < 0.05) on primary histology. Positive SLNB was significantly associated with greater tumour thickness (mean Breslow thickness 3.8 vs. 2.3 mm, P < 0.05), but no significant differences were observed for mitotic rate, presence of regression or ulceration, or in BRAF or NRAS mutations (P > 0.05). Patients with a positive SLNB had a significantly higher odds of mortality compared with those with a negative SLNB (odds ratio 0.14, P < 0.05). SLNB candidates were significantly more likely to receive SACT than patients who were not offered this (22%, n = 28 vs. 7%, n = 11; P < 0.001). However, there was no difference in mortality (12%, n = 15 vs. 19%, n = 28; P > 0.05). In conclusion, SLNB is an important tool in melanoma management, with recent UK and US guidelines recommending increasing consideration of SLNB, particularly in all patients with Breslow thickness > 1 mm. As SLNB becomes increasingly integrated into clinical practice, our study highlights the important role of SLNB in managing higher-risk patients and providing access to SACT. Why mortality significantly differs between those diagnosed through teledermatology vs. face-to-face needs further investigation, but it highlights the safety of teledermatology-directed care in the skin cancer pathway.