Risk Factors for Melanoma Survival: DGCR8 as a Predictive Factor for Mortality in Young Patients

MicroRNA-processing enzymes - Dicer and DGCR8 - have been found to be dysregulated in melanoma. This study investigated whether these microRNA-processing enzymes could be used as risk factors for mortality. A retrospective cohort including medical history and samples of 74 patients was reviewed. Clinical and pathological variables were compared with mortality. Percentage of immunoreactive tumour cells (%IRC) for each enzyme was evaluated using immunohistochemistry. A dichotomous breakdown of DGCR8 and Dicer expression (negative or positive test) was performed using a cut-off of 80% IRC. The 5-year survival rate of stage 0-I-II was 89.5% and stage III-IV was 18.5%. In the bivariate analysis, variables associated with lower survival were: aged over 42 years, histologic subtypes, Breslow thickness ≥ 0.8mm, ulceration, vascular invasion, metastatic melanoma, positive sentinel node, more than 1 positive node, LDH > 200 IU/L, distant metastasis, and stage III-IV. In the multivariate Cox model, the analysis for stage III-IV showed a significantly lower survival curve in patients with a positive DGCR8 test and aged ≤ 42 years (p = 0.0152, Wald test). The Cox proportional hazards model showed that a positive DGCR8 test was a predictive factor for mortality in patients aged ≤ 42 years (HR = 14.3, 95%CI 1.5-140, p = 0.024). This study highlights a potential biomarker for melanoma survival and its utility in stratifying high-risk patients.