P210 A report on the national epidemiology of melanocytic and spitzoid tumours of uncertain malignant potential (MELTUMPs and STUMPs) in England from 2013 to 2022

Abstract

Melanocytic tumours of uncertain malignant potential (MELTUMPs), including spitzoid tumours of uncertain malignant potential (STUMPs), are a group of histologically ambiguous melanocytic lesions, which lack definitive histological criteria for classification as either benign naevi or malignant melanoma. This study aims to report the epidemiology, demographics and survival of patients with MELTUMPs and STUMPs in England. We analysed data from the National Disease Registration Service (NDRS) using the ‘Get Data Out’ dataset, including all registered cases in England diagnosed between 2013 and 2022. Kaplan–Meier overall and net survival analyses are reported at 5 years. In total 810 cases were identified, with a median of 83.5 cases per year (interquartile range 72.5–94.3). The cohort was predominantly female (64.3%, n = 521) and had a median age band of 35–39 years. White ethnicity made up the largest proportion of cases (76.4%, n = 619), with 21.7% (n = 176) of unknown ethnicity. The age-standardized rate per 100 000 population was 0.09 [95% confidence interval (CI) 0.06–0.11] in 2013 and 0.15 (95% CI 0.12–0.18) in 2022. Analysis by Index of Multiple Deprivation revealed no significant difference across socioeconomic groups [x2(4) = 4.07, P = 0.40], ranging from 17.4% in quintile 1 (most deprived) to 21.4% in quintile 4. The 5-year overall survival was 98.5% (95% CI 95.3–99.5) and 5-year net survival was 100.8% (95% CI 98.9–102.7). NHS data flows may not be optimized to notify NDRS of all benign tumours, and tumours of unknown malignant potential are not quality assessed to the same rigour as malignant tumours. Therefore, cases may be undercounted. Classification of cases as MELTUMP will vary by pathologist and may represent a placeholder for cases that are difficult to classify. This provides the first national report on the epidemiology of MELTUMPs and STUMPs in England, offering insight into these poorly understood lesions.