An analysis of lactate dehydrogenase (LDH) levels in advanced stage IV melanoma of the skin: prognostic capabilities and demographic variability.

Despite its limitations, in part due to decreased specificity in advanced disease, serum lactate dehydrogenase (LDH) is one of few serum factors used in cancer staging. This study quantifies the predictive capabilities of LDH in stage IV melanoma of the skin and explores the validity of suggested demographic discrepancies which may exist in its use. The 1975-2017 Surveillance Epidemiology and End Results (SEER) database was queried for stage IV cutaneous melanoma cases. Demographic characteristics were compared between LDH groups using chi-square and t tests. Subsequent Cox multivariable regression was performed to assess survival differences. 334 cases of stage IV cutaneous melanoma (average age: 63.0 years) with measured serum LDH levels were identified. Of these patients, 150 (44.9%) had normal LDH, 112 (33.5%) had LDH < 1.5 × upper limit of normal (ULN), 57 (17.1%) had LDH 1.5-10 × ULN, and 15 (4.5%) had LDH > 10 × ULN. Lower incomes were associated with higher LDH; individuals with incomes < $50,000 had the greatest proportion of LDH 10 × ULN (19.2%; p = 0.0031). LDH > 10 × ULN also had the lowest proportion of White patients (p = 0.04). On Cox multivariable survival analysis, increasing LDH levels showed increased risk of death (LDH < 1.5 × ULN: HR = 2.05, p = 0.01; LDH 1.5-10 × ULN: HR = 1.46, p < 0.001; LDH > 10 × ULN: HR = 5.91, p < 0.001). This study reaffirms the utility of LDH as a significant predictor of mortality with incremental severity, suggesting possible use for mortality projections. We note that Black patients and those with lower incomes may be more likely to have an elevated LDH. Older age groups and presence of ulceration among patients with stage IV melanoma were also associated with a greater risk of mortality.