Cutaneous melanoma incidence—Evidence of a flattening curve
Authors: Juliana Berk-Krauss, Medha Sharma, David Polsky, Alan C. Geller
Journal: Journal of the American Academy of Dermatology (2023)

To the Editor: Cutaneous melanoma is one of the few malignancies with a rising incidence; yet, its mortality rate has sharply decreased due to highly-effective systemic therapies for metastatic melanoma.1Siegel R.L. Miller K.D. Fuchs H.E. Jemal A. Cancer statistics, 2022.CA Cancer J Clin. 2022; 72: 7-33https://doi.org/10.3322/caac.21708Crossref PubMed Scopus (6573) Google Scholar,2Berk-Krauss J. Stein J.A. Weber J. Polsky D. Geller A.C. New systematic therapies and trends in cutaneous melanoma deaths among US Whites, 1986-2016.Am J Public Health. 2020; 110: 731-733https://doi.org/10.2105/AJPH.2020.305567Crossref PubMed Scopus (87) Google Scholar Whether a true "melanoma epidemic" exists is debated. In 2021, Welch et al argued that the unabated rise in cutaneous melanoma incidence represents an "epidemic of diagnosis"—a result of overbiopsying and upstaging "gray-zone" thin melanomas, and thus, population-wide screening should stop.3Welch H.G. Mazer B.L. Adamson A.S. The rapid rise in cutaneous melanoma diagnoses.N Engl J Med. 2021; 384: 72-79https://doi.org/10.1056/NEJMsb2019760Crossref PubMed Scopus (209) Google Scholar However, their data were drawn from an old Surveillance, Epidemiology, and End Results (SEER) Program data set (9 registries, 1975-2017) and lacked subgroup analyses. We sought to update and augment their analysis to identify if any populations could benefit from enhanced surveillance. Using SEER∗Stat Version 8.4.0, we analyzed 20-year incidence data (2000-2019) from 17 SEER registry areas in individuals aged 20+ years, stratified by age and tumor thickness. Cutaneous melanoma cases were defined by histology (8720-8790) and skin primary site (C44.0-C49.0) codes. Melanomas in situ (MMIS) were defined as having in situ histologic behavior. Invasive melanoma (IM) tumor thickness was reported according to American Joint Committee on Cancer (AJCC) eighth edition criteria (T1, ≤1.0 mm; T2, >1.0-2.0 mm; T3, >2.0-4.0 mm; T4, >4.0 mm). Age-adjusted incidence rates were plotted over time. The maximum number of possible joinpoints was set to 5, based on the number of data points (Joinpoint Regression Program v5.0.2; https://surveillance.cancer.gov/joinpoint/).4Kim H.J. Fay M.P. Feuer E.J. Midthune D.N. Permutation tests for joinpoint regression with applications to cancer rates.Stat Med. 2000; 19 (correction: 2001;20:655). https://doi.org/10.1002/(sici)1097-0258(20000215)19:3<335::aid-sim336>3.0.co;2-z: 335-351Crossref PubMed Scopus (3825) Google Scholar A permutation test determined the location of the joinpoints when the change in trend was statistically significant. The slope of each line was recorded as the annual percent change (APC). APCs were considered statistically significant if P < .05. We found that overall MMIS and IM rates increased from 2000 to 2019, but flattened beginning in 2014-2015 (Supplementary Fig 1, available via Mendeley at doi.10.17632/b2wd5rbrzx.1). A similar trend was observed among individuals aged 70+, the population most affected by melanoma. Their MMIS and IM incidence rates also rose over the study period, with rate of change slowing since 2014 to 2015. Conversely, individuals aged <40 exhibited a flat or decreasing MMIS trend from 2000 to 2019, and those aged <50 experienced a flat or decreasing IM trend. For individuals aged 70+, this flattening curve appeared to be driven by fewer "gray-zone" melanomas. Specifically, there was a significantly lower rise in the incidence of MMIS after 2015 (2000-2015 APC: 6.35; 2015-2019 APC: 1.28, P < .05, Supplementary Fig 2, available via Mendeley at doi.10.17632/b2wd5rbrzx.1) and a decrease in the incidence of thin melanomas (T1, ≤1 mm) since 2014 (2014-2019 APC: −1.71, P < .05, Fig 1). However, there remained a significant rate of increase in T4 (>4 mm) tumors in patients aged 70+ throughout the study period (2000-2010 APC: 7.34; 2010-2019 APC: 3.21, P < .05, Fig 2).Fig 2T4 invasive melanoma incidence in patients aged 70+, 2000-2019. T4: >4 mm thick invasive melanoma. Annual percent changes are noted in the figure legends. ∗ Indicates that the annual percent change is significantly different from 0 at the alpha = 0.05 level. APC, Annual percent change.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Our study provides evidence of abatement in thin melanoma incidence rates since 2014 to 2015 (prior to COVID-19-related interruptions).5Stonesifer C.J. Yilmaz M.M. Niedt G.W. Assessment of clinical interruptions during the COVID-19 pandemic on the diagnosis of melanoma: a 30-month retrospective review.JAAD Int. 2023; 10: 25-27https://doi.org/10.1016/j.jdin.2022.07.004Abstract Full Text Full Text PDF PubMed Scopus (1) Google Scholar However, older patients still face increasing rates of thick melanomas, which likely represents a true increase in incidence, as these are clearly not "gray-zone" tumors. Older individuals may benefit from improved surveillance efforts to diagnose earlier-stage melanomas. Further studies are required to uncover key drivers of these emerging trends. None disclosed.