New Zealand patients have a higher melanoma burden in sentinel nodes and completion lymphadenectomy than patients in MSLT-II.

New Zealand has the highest rate of melanoma-related mortality in the world. Access to immunotherapy and radiology is limited and surgical treatment of regional disease remains important. A recent pilot study of a single health district observed a higher nodal melanoma burden than was reported in the second Multicentre Selective Lymphadenectomy Trial (MSLT-II). In this study, a series of regional censuses were undertaken covering the 10 years immediately prior to the publication of MSLT-II. The study population was seven District Health Boards covering 62.2% of the population of New Zealand across a 10-year period preceding MSLT-II. The primary outcomes measured were the size of sentinel lymph node metastases and non-sentinel node (NSN) positivity on completion lymph node dissection (CLND) for patients with a positive sentinel lymph node biopsy (SLNB). In the 2323 SLNB identified, the mean sentinel lymph node metastatic deposit size was larger compared to MSLT-II (2.55 vs. 1.07/1.11 mm). A greater proportion of New Zealand patients (44.2%) had metastatic deposits larger than 1 mm compared to MSLT-II (33.2/34.5%) and the rate of non-sentinel node involvement on CLND was also higher (22.2% vs. 11.5%). These findings indicate that New Zealand is a high-risk population for nodal melanoma metastases. Due to these differences, the conclusions of MSLT-II may not be able to be applied to melanoma patients in the 7 regions studied in New Zealand.

Melanoma sentinel lymph node biopsy and completion lymph node dissection: A regional hospital experience.

Completion lymph node dissection (CLND) following positive sentinel lymph node biopsy (SLNB) for cutaneous melanoma is a topic of controversy. The second Multicenter Selective Lymphadenectomy Trial (MSLT-II) suggested no survival benefit with CLND over observation amongst patients with a positive SLNB. The findings of the MSLT-II may have limited applicability to our high-risk population where nodal ultrasound and non-surgical melanoma treatment is rationed. In this regional, retrospective study, we reviewed primary melanoma, SLNB and CLND histopathological reports in the Bay of Plenty District Health Board (BOPDHB) across a 10-year period. The primary outcomes measured were size of sentinel lymph node metastases and non-sentinel node (NSN) positivity on CLND for patients with a positive SLNB. In the 157 SLNB identified, the mean sentinel lymph node metastatic deposit size was larger in BOPDHB compared with MSLT-II (3.53 vs 1.07/1.11mm). A greater proportion of BOPDHB patients (54.8%) had metastatic deposits larger than 1mm compared with MSLT-II (33.2/34.5%) and the rate of NSN involvement on CLND was also higher (23.8% vs 11.5%). These findings indicate that the BOPDHB is a high-risk population for nodal melanoma metastases. Forgoing CLND in the context of a positive SLNB may place these patients at risk.