Sentinel node tumor burden in cutaneous melanoma. Survival with competing risk analysis and influence in relapses and non-sentinel node status: retrospective cohort study with long follow-up in a Spanish population

Several authors have studied the potential of sentinel lymph node (SLN) tumor burden as prognostic factor but the microscopic classifications used in different study groups were variable. We examined the prognostic role of tumor burden in SLN on melanoma specific-survival and competing causes of death. We also analysed clinical and histological factors as predictors of disease relapses and additional non sentinel lymph node (NSLN) metastases. We included all patients with cutaneous melanoma that underwent SLN biopsy between 2002 and 2012 at Complejo Hospitalario de Navarra (Spain). The study end-points were death due to melanoma, melanoma relapse and involvement of NSLN. We used Fine-Gray test for competing risk analysis. A logistic regression model was performed to predict the risk of involvement of NSLN. Between 2002 and 2012, there were 348 patients who underwent SLN biopsy in our centre (308 were eligible for the study). 26.9% patients positive SLN. 88 patients died during the follow-up period and 66 (75%) died from melanoma. The 5-year cumulative incidence of melanoma death was 15.33% (95 % CI 15.25-15.42). The cumulative probability of death from melanoma was associated with gender, histological subtype, Breslow thickness, mitotic rate, ulceration and SLN tumor burden. In multivariable analysis, Breslow thickness and SLN tumor burden remained as independent prognostic factors. SLN tumor burden appears to be an important prognostic factor. It is very important reporting these characteristics in pathological reports. More prospective studies would be necessary to analyze these variables and to be able to make recommendations in management of melanoma patients.