Abstract 62: Melanoma Incidence Trends by Population Group in South Africa, 1991–2021

Abstract Purpose: South Africa (SA) has a diverse population, with varying skin phenotypes. Melanoma incidence in SA has increased over the past decade, making it one of the top 10 reported cancers attributed to varied risk factors. Analyzing melanoma incidence trends by population group in SA is useful for understanding the epidemiology of melanoma. This study aims to provide a 30-year trend analysis of melanoma cancer in SA. Methods: A retrospective cohort study using the SA National Cancer Registry database analyzed melanoma incidence trends from 1991 to 2021. The age-standardized incidence rate (ASR) was calculated using the Segi-World Standard Population, and the annual percent change (APC) by population group was estimated using Joinpoint Regression. Results: Pathologically confirmed melanoma cases accounted for 39.6% (18,665/47,177). Among the White population, ASIR increased from 0.77/100,000 in 1991 to 2.00/100,000 in 1997, with an APC of 20.21% (CI: 13.77–32.22). This was followed by a decline of 26.58% from 1997 to 2000, reducing the ASIR to 0.73/100,000 (CI: −31.68–13.84). A further decrease of 2.36% occurred between 2000 and 2010 (ASIR: 0.73–0.53/100,000; CI: −9.69–2.40). From 2010 to 2015, the ASIR increased by 13.79% (ASIR: 0.53–1.31/100,000; CI: 5.10–29.88), followed by a decline of 1.67% from 2015 to 2021. The Coloured population experienced a significant ASIR increase of 40.36% (0.07–0.78/100,000; CI: 20.98–98.61) from 1991 to 1998, followed by stabilization and a decline of 0.51% annually from 1998 to 2021. In the Black population, ASIR increased by 9.40% (0.05 to 0.13/100,000; CI: 5.16–18.74) between 1991 and 1999, then declined annually by 2.41% from 1999 to 2021 (CI: −3.06 to −1.81). The Asian population showed a non-significant ASIR increase of 1.52% over the study period (CI: −0.18–4.64). Conclusion: This study highlights population-related differences in melanoma incidence trends, with higher rates observed in the White and Coloured populations. The findings offer valuable insights into how factors such as UV radiation, skin phenotype, HIV epidemic, socioeconomic development, lifestyle, and occupation are influencing melanoma risk over time in SA’s diverse population. Strengthening prevention strategies and improving early detection are essential to enhancing survival outcomes for those at risk. Citation Format: Rethabile Whitney Mothosola, Caradee Yale Wright, Babongile Ndlovu, Judith Mwansa-Kambafwile. Melanoma Incidence Trends by Population Group in South Africa, 1991–2021 [abstract]. In: Proceedings of the 13th Annual Symposium on Global Cancer Research; 2025 Sep 16. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2025;34(12_Suppl):Abstract nr 62.