Background
Completion lymph node dissection (CLND) used to be a standard of care for melanoma with a positive sentinel lymph node biopsy (SLNBx). There has been an appreciable change in clinical management of SLNBx positive patients since the MSLT-II trial was published in 2017 [1]. Patient and disease factors differ between the MSLT-II cohort and NZ patients. We compare demographic and disease data and patient outcomes to ascertain the relevance of MSLT-II in the NZ setting.
Methods
We analysed all positive sentinel nodes for melanoma at Dunedin Hospital between 2007 and 2022. We recorded the baseline characteristics of patients, and the 3-year melanoma-specific survival (MSS) and disease-free survival (DFS) in pre-MSLT and post-MSLT groups. The two groups were defined as having a positive SLN before or after the publication of MSLT-II (June 2017). We compared these local results to the results published in the MSLT-II study.
Results
There were 275 SLNBx, of which 55 had a positive SLN and were included in the study (mean age 63.6 years [range 23 – 86], 37 male and 18 female). Local patients had a thicker Breslow thickness (3.53mm [range 0.9 – 13] vs 2.73mm [range 0.34 – 30.0]) and larger SLN metastases compared to the MSLT-II population (3.29mm [IQR 1.83 – 3.7] vs 1.09mm [IQR 0.25 – 1.35]). CLND rate in the pre-MSLT-II group (34 patients) was 85.3%, and in the post-MSLT-II group (21 patients) was 33.3% (p<0.01). Three-year MSS was 73.0% and 75.7% (p=0.97), DFS was 64.3% and 67.2% (p=0.96) in pre-MSLT and post-MSLT groups respectively.
Conclusion
Our management of positive SLN has changed since the publication of MSLT-II without affecting the three-year MSS rates locally. The local MSS rate (74%) is lower than the rate reported in MSLT-II (86%) and this may be a reflection on worse prognostic melanomas in NZ.