An analysis of risk factors for cutaneous melanoma by anatomical site (Australia)

Emerging evidence suggests that melanomas arising on the head and neck that are not lentigo maligna melanomas have different associations with phenotypic and environmental risk factors than those on the trunk and other sites. We sought to test this hypothesis in a population-based study in Queensland, Australia.

Risk factor data were collected from 2360 participants with incident cutaneous melanoma diagnosed 1982--1990, including 167 participants with lentigo maligna melanoma. For each risk factor, polytomous logistic regression analysis, using the trunk as a reference category, was used to estimate the odds ratio and 95% confidence interval for cutaneous melanomas by anatomical site.

Participants with melanomas of the head and neck were significantly older than those with melanomas of the trunk (males 52.7 versus 49.7 years; females 47.8 versus 40.5 years). Compared with patients with truncal melanomas, those of the head and neck were less likely to have many nevi (OR 0.41, 95% CI 0.13--1.31), although this did not reach statistical significance. Among females, melanomas of the lower limb were negatively associated with a past history of non-melanoma skin cancer (OR 0.41, 95% CI 0.23-0.74).

We have observed heterogeneity for melanoma risk by anatomical site, lending weight to the hypothesis that cutaneous melanomas may develop through multiple causal pathways.