Population-based assessment of sentinel lymph node biopsy in the management of cutaneous melanoma

Sentinel lymph node biopsy (SLNB) for melanoma plays a central role in determining prognosis and guiding treatment and surveillance strategies. Despite widely published guidelines for SLNB, variation exists in its use. We aimed to determine the frequency of and predictive factors for SLNB in patients with clinically node-negative melanoma in British Columbia.

A retrospective review was performed of patients with clinically node-negative melanoma diagnosed between January 2015 and December 2017. Patients included had a Breslow depth greater than 0.75 mm or a Breslow depth less than or equal to 0.75 mm with ulceration, or a mitotic rate greater than or equal to 1/mm². SLNB was considered to be indicated for clinical stages IB to IIC (American Joint Committee on Cancer's AJCC Cancer Staging Manual, seventh edition).

A total of 759 patients were included. SLNB was performed in 54.8% (363/662) of patients when indicated. SLNB was more likely to be performed for tumours with a Breslow depth greater than 1.0 mm or a mitotic rate greater than or equal to 1/mm². SLNB was less likely to be performed in patients older than 75 years and with a nonextremity tumour location. Compliance with SLNB guidelines decreased distant recurrence but did not significantly affect regional recurrence, nor did it have a significant impact on overall survival among patients aged 75 years and younger.

SLNB is being underutilized in British Columbia. These results are concerning and highly relevant given the rapidly evolving field of adjuvant systemic therapy for high-risk patients and the increased proportion of patients who should be considered for SLNB on the basis of the eighth edition of the AJCC Cancer Staging Manual and current guidelines. Efforts should be made to increase the use of SLNB in appropriate patients.