Original Articles: Epidemiology of MelanomaEstimated risk of progression of lentigo maligna to lentigo maligna melanomaMenzies, Scott W.a,,c; Liyanarachchi, Sakithaa; Coates, Elliota; Smith, Annikad; Cooke-Yarborough, Clairee; Lo, Serigned; Armstrong, Brucec,,f; Scolyer, Richard A.b,,c; Guitera, Pascalea,,c,,dAuthor Information aSydney Melanoma Diagnostic Centre bAnatomical Pathology, Royal Prince Alfred Hospital cSydney Medical School, The University of Sydney, Camperdown dMelanoma Institute Australia, The University of Sydney, Wollstonecraft eNew South Wales Cancer Registry, Cancer Institute NSW, Alexandria fSchool of Global Population Health, The University of Western Australia, Perth, Australia Received 5 December 2018 Accepted 5 April 2019 Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s website, www.melanomaresearch.com. Correspondence to Scott W. Menzies, Discipline of Dermatology, Sydney Medical School, The University of Sydney, at the Sydney Melanoma Diagnostic Centre, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia, Tel: +61 4 1963 1557; fax: +61 2 9515 5278; e-mail: firstname.lastname@example.org Melanoma Research: April 2020 - Volume 30 - Issue 2 - p 193-197 doi: 10.1097/CMR.0000000000000619 Buy SDC Metrics Abstract Little is known about the risk of progression of lentigo maligna to lentigo maligna melanoma. We determine the annual risk of progression of lentigo maligna to lentigo maligna melanoma by analysing a prospective population-based survey of recently diagnosed anterior (visible in a mirror) head and neck lentigo malignas and lentigo maligna melanomas. Six hundred eighty-two consecutive patients aged 18–80 years with non-recurrent lentigo maligna or lentigo maligna melanoma, diagnosed between 1 July 2015 and 20 April 2016, were identified from pathology notifications to the New South Wales Cancer Registry (Australia) and sent survey questionnaires soon after diagnosis (median 4.6 months interquartile range: 3.8–5.7). Details of the time the lesion was present and when changes to it were noticed before diagnostic biopsy were ascertained by surveying the patients, of whom 53.5% agreed to participate. There was little difference between the proportions of lentigo maligna melanoma and lentigo maligna in the consenting and non-consenting patients (P = 0.56). Two hundred twenty-eight lentigo maligna (median age 67 years, range: 38–80) and 33 lentigo maligna melanoma (70 years, 43–80) were surveyed. There was no difference between the time lentigo maligna melanoma was present on the skin (median 18 months, range: 0–690) and the time lentigo maligna was (18 months, 0–665) (P = 0.972). The estimated risk of progression of lentigo maligna to lentigo maligna melanoma was 3.5% per year (95% confidence interval: 2.5–5.0). This equates to an average time for lentigo maligna to progress to lentigo maligna melanoma of 28.3 years (95% confidence interval: 20.0–40.5) in this population. Although our data suggests that the annual progression rate of lentigo maligna is more than 25 times greater than previously suggested, the rate is still low. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.