Melanoma incidence continues to rise in different populations and ethnic groups worldwide.1–3 Epidemiological data and known risk factors for melanoma are mostly based on studies of US, Australian, and European populations. Few population-based studies have been conducted in Latin American or Hispanic communities.4

Latin America is known for its significant ethnic diversity secondary to interracial relationships that vary from one country to the next depending on population structure and migration history. In Colombia, for example, the population results from interactions between indigenous/native populations, Spanish people, and Africans, with mestizos representing the largest segment. The aim of this study was to identify possible risk factors for cutaneous melanoma in a Colombian population in the city of Medellín, Colombia.

We conducted a retrospective age- and sex-matched case-control study. Cases were patients with a histopathologically confirmed diagnosis of in situ or invasive melanoma, while controls were randomly selected patients without a personal history of melanoma who were seen for any dermatologic condition. The ratio of cases to controls was 1:2. We analyzed the medical records of patients older than 18 years seen at Clínica Aurora, a specialized skin cancer center, in Medellín between May 2014 and October 2017. We included both incident and prevalent cases of melanoma. In other words, we studied patients newly diagnosed with melanoma during the study period and those with an existing diagnosis. The required sample size was estimated at 62 cases and 125 controls using an alpha error of 5%, a beta error of 20% (95% confidence level and 80% statistical power) and an odds ratio (OR) of 3 associated with the presence of multiple melanocytic nevi as the main risk factor for melanoma. The calculations were performed in the statistical software program Epi Info.

We analyzed the medical records of 187 patients (62 cases and 125 controls). Their phenotypic, sociodemographic, and sun exposure characteristics are given in Table 1. Table 2 summarizes the characteristics of the patients with melanoma. Table 3 presents the results of the bivariate and multivariate analyses.

Similarly to previous reports in the literature,5–7 our multivariate analysis showed that patients with melanoma were more likely to have a history of recreational or intermittent sun exposure (OR = 4.2; 95% CI, 1.8-9.6) and a lifetime history of sunburn (OR = 5.6; 95% CI, 2.2-14.6), suggesting that these patterns of exposure are risk factors for melanoma in our study population. In contrast, the use of 2 or more sun protection measures exerted a protective effect (OR = 0.2; 95% CI, 0.1-0.5). Unlike other studies, we did not observe an association between number of common or atypical nevi and melanoma risk.5,8 We observed a protective effect for a personal history of basal cell carcinoma, possibly because the control population was selected from a specialized center where patients with skin cancer predominate and basal cell carcinoma would be expected to be relatively common.

Our study has some limitations. First, the controls were selected from a referral center for patients with skin cancer and their exposure habits may not be representative of the general population in the area, possibly resulting in an overestimation of the proportion of patients with a history of skin cancer and creating a bias in our results for use of sun protection measures, access to health care, and level of education. Second, recall bias may have affected the accuracy or completeness of important data for our analyses, as some of the information was based on subjective perceptions of past events.

In conclusion, recreational or intermittent sun exposure and a lifetime history of sunburn were risk factors for melanoma in our study population, while use of 2 or more sun protection measures exerted a protective effect. Our findings are consistent with reports from different regions in the world, indicating that UV radiation plays an important role in populations other than Whites and that primary prevention efforts are also essential for preventing skin cancer in mestizo populations such as those in Colombia.