Epidemiology of lentigo maligna and lentigo maligna melanoma in England between 2013 and 2023

Lentigo maligna (LM) is a melanoma in situ usually found on the sun-exposed skin of older adults. Data on the risk of progression to lentigo maligna melanoma (LMM) are limited. Outcomes without surgical treatment are unknown.

To describe the characteristics of patients with LM and LMM; to identify the incidence of LM and LMM in England from 2013 to 2023; and to calculate the survival of this cohort and estimate the risk of progression of LM to LMM, as well as its modifying factors.

Pseudonymized data for LM and LMM in England between 2013 and 2023 were provided by the National Disease Registration Service. Joinpoint regression was used to calculate incidence rates for LM and LMM. Kaplan-Meier curves were used for melanoma-specific and all-cause survival. The cumulative incidence of LMM after LM was calculated using a latency period of 6 months or 1 year, for identical or plausibly matching sites. Cox regression was used to explore the influence of covariates on survival and progression.

Age-standardized incidence rates of LM [4.91-5.03 per 100 000 person-years (PY), annual percentage change (APC) 0.25, 95% confidence interval (CI) -2.68 to 3.35] and LMM (1.84-1.97 per 100 000 PY, APC 0.59, 95% CI -2.31 to 3.76) remained stable from 2013 to 2019, decreased in 2020 and increased in 2023 to higher than prepandemic levels. Patients with LM and LMM were more likely to die from other cancers or cardiovascular disease than from melanoma. Female sex (hazard ratio 0.56, 95% CI 0.49-0.66; P < 0.001) was protective, while increasing age conferred a higher risk of dying from melanoma. The risk of progression of LM to LMM was 1.0% (95% CI 0.8-1.1) at 10 years and increased with age and for tumours located on the head and neck.

The incidence rates of LM and LMM in the future will clarify if the post-COVID-19 pandemic increases are due to delayed presentations or a true rise in cases. The excellent net and overall survival of patients with LM, together with the low risk of progression to LMM, favour patient-centred discussions in the management of LM in older, frailer adults. The risk of progression without treatment requires further evidence.