BACKGROUND: Lentigo maligna (LM) is a melanoma in situ usually found sun on exposed skin in older adults. Data on the risk of progression to lentigo maligna melanoma (LMM) are limited. Outcomes without surgical treatment remain unknown. OBJECTIVES: To describe the patient characteristics of those with LM/LMM, identify the incidence of LM/LMM in England over 2013 to 2023, calculate the survival of this cohort and estimate the risk of progression of LM to LMM, as well as its modifying factors. METHODS: Pseudonymised data for LM/LMM in England between 2013-2023 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. 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. RESULTS: Age-standardised incidence rates of LM (4.91-5.03 per 100,000 person years, APC: 0.25, 95% CI: -2.68 to 3.35) and LMM (1.84-1.97 per 100,000 person years, APC: 0.59, 95% CI: -2.31 to 3.76) remained stable over 2013-2019, reduced in 2020 and further increased to higher than pre-pandemic levels in 2023. Patients with LM and LMM were more likely to die from other cancers or cardiovascular disease than from melanoma. Female gender (hazard ratio (HR) 0.56, 95% CI: 0.49 to 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% to 1.1%) at 10 years and increased with age and for tumours located on the head and neck. CONCLUSIONS: LM/LMM incidence rates in the future will clarify if the post-Covid-19 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.
Karponis et al. (Thu,) studied this question.