European ancestry and cutaneous melanoma in Southern Brazil

Similar to other countries, incidence and mortality rates for cutaneous melanoma (CM) are increasing in Brazil. Resulting from centuries of ethnic mixture, the skin of the Brazilian population presents all phototypes, being progressively lighter following the increase of the latitude toward the South, where the highest incidence of melanoma is observed. Studies from the United States and Argentina in whites suggest that European ancestry could represent an important risk factor for CM in those regions.

Questionnaires from a case-control study involving 119 melanoma patients and 177 controls were reviewed for age, gender, phototype, sun exposure, photoprotection and ancestry. The patients reported the countries of ancestry of their grandparents. Data were tabulated and converted into scores that would reflect the proportion of ancestry for each country in individuals.

Patients with German and Italian ancestry presented higher risk for CM [odds ratio (OR), 3.5; 95% confidence interval (95% CI), 1.8-6.7 and OR, 9.7; 95% CI, 3.9-24.2, respectively]. Conversely, Brazilian indigenous ancestry showed a protective effect for the development of the disease, with an OR of 0.16 (95% CI, 0.04-0.7).

Some European ancestries, especially German and Italian, seem to be associated to a higher risk of CM in this sample from Southern Brazil. On the other hand, Brazilian indigenous ancestry presented as a protection factor against developing the tumour.