Changing Patterns of Cutaneous Melanoma Mortality in Brazil: A Nationwide Time-Series Analysis (2000-2024)

Abstract

Background: Cutaneous melanoma accounts for most deaths from skin cancer, and mortality is consistently higher in men than in women. National trends in Brazil have not been characterized using population estimates rebased to the 2022 Census. Materials and methods: We conducted a nationwide ecological time-series study of deaths from cutaneous melanoma (ICD-10 C43) recorded in Brazil’s Mortality Information System from 2000 to 2024. Population denominators were obtained from the 2024 revision of the Brazilian Institute of Geography and Statistics projections, rebased to the 2022 Census. Rates were directly age-standardized to the 2022 Brazilian population; 95% confidence intervals (CIs) were estimated using the Fay-Feuer gamma method, a standard approach for deriving exact confidence limits for standardized rates from count data. National and subgroup trends were assessed using segmented log-linear regression, which identifies the calendar years in which a trend changes direction. Differences by sex, region, and age group were examined using age-adjusted negative binomial models with population offsets, which compare death rates between groups of different population sizes. The sex interaction was prespecified as a secondary, exploratory comparison and was not adjusted for multiple testing. The COVID-19 period was assessed using an interrupted time-series model with 2020 specified a priori. Results: Between 2000 and 2024, 38,346 deaths were attributed to cutaneous melanoma. Annual deaths increased from 1,027 to 2,031, whereas the age-standardized rate was essentially unchanged, from 0.91 to 0.92 per 100,000 population. Mortality increased by 0.83% per year (95% CI 0.52 to 1.14) until 2016 and declined by 1.12% per year (−1.69 to −0.54) thereafter. The full-period average annual percentage change (AAPC) was 0.17% (−0.01 to 0.36; p = 0.065). Men had higher rates throughout. Sex-specific segmented models showed an increase followed by a decline in men and an overall stable trend in women. An exploratory, non-multiplicity-adjusted interaction offered limited and inconsistent evidence of a more favorable trajectory in women than in men (p = 0.037). Mortality declined in all groups younger than 60 years and increased overall among adults aged 60 years or older, although the rise leveled off after 2015. The Southeast declined, the South was stable overall, and the North and Northeast increased from very low initial rates. The pandemic was associated with a one-time 6.60% downward shift in mortality in 2020, without a change in slope. Using population estimates not rebased to the 2022 Census changed the national AAPC from 0.17% (−0.01 to 0.36) to −0.39% (−0.60 to −0.18). Conclusions: The increasing number of melanoma deaths in Brazil was driven largely by population growth and aging rather than by a sustained increase in age-standardized mortality. A national decline began around 2016, but trends remained heterogeneous by age and region. The material change in the national AAPC after revision of the population denominators demonstrates that denominator vintage is not merely a technical consideration in long-term mortality studies but can materially affect epidemiological conclusions.