Practice variation in Sentinel Lymph Node Biopsy for melanoma patients in different geographical regions in the Netherlands

Background: Due to the lack of solid evidence for treatment benefit of Sentinel Lymph Node Biopsy (SLNB) as part of loco-regional surgical treatment of non-distant metastatic melanoma, there might be variation in surgical treatment strategies in the Netherlands. The objective of the current study was to assess differences in the performance of SLNB, in geographical regions in the Netherlands, of non-distant metastatic melanoma patients (American Joint Committee on Cancer (AJCC) stage I-III).Materials and methods: A total of 28 550 melanoma patients, diagnosed between 2005 and 2013, were included in this population based retrospective study. Data were retrieved from the Netherlands Cancer Registry (NCR). Treatment strategies in 8 regions of the Netherlands were compared according to stage, excluding patients with distant metastasis (AJCC stage IV).Results: Throughout the Netherlands, there was substantial practice variation across the regions. The performance of SLNB in patients with clinically unsuspected lymph nodes and Breslow thickness >1.0 mm was significantly different between the regions. In a post hoc analysis, we observed that patients aged over 60 years, female patients and patients with a melanoma located in head and neck have lower odds to receive a SLNB.Conclusion: There is considerable loco-regional practice variation which cannot completely be explained by the patient and tumor characteristics, in the surgical treatment of non-distant metastatic melanoma patients in the Netherlands. Although national guidelines recommend considering SLNB in all patients with a melanoma thicker than 1 mm, only half of the patients received a SLNB. Future research should assess whether this practice variation leads to unwanted variations in clinical outcome.