The aim of this study was to determine
therapy-related risk factors for the development of
melanoma after
hemangioma. A cohort study was conducted among 4620 patients treated before 16 years of age for skin
hemangioma in France. A nested case-control study was also conducted on 13 patients who developed a
melanoma (cases) matched with five controls in cohort according to sex, age at the
hemangioma diagnostic, the calendar year of occurrence of the
hemangioma, and follow-up. The radiation dose received at the site of the
melanoma and at the same site in controls was estimated, and named 'local dose'. A total of 13
melanomas were registered during an average follow-up of overall 35 years, the risk of developing
melanoma after a
hemangioma treatment was 2.5-fold higher [95% confidence interval (CI): 1.4-4.1] compared with that of the general population, this ratio being only 0.8 (95% CI: 0.05-3.6) in 896 patients who did not receive
radiotherapy, but 3.0 (95% CI: 1.6-5.1) after
radiotherapy. When adjusting on sex, age, and year of the treatment and follow-up duration,
melanoma risk was 11.9 (95% CI: 1.4-123) times higher in patients treated with ytrium 90 than in the ones who did not received
radiotherapy. In the case-control study, the risk of
melanoma was not linked to the local radiation dose. Indeed, the increase in
melanoma risk was observed even for very low local doses. Compared with the corresponding skin areas in patients who did not receive
radiotherapy, the ones having received less than 0.001 Gy had a
melanoma risk of 3.9 (95% CI: 0.5-32) and those who received more than 0.01 Gy had a risk of 6.9 (0.5-99). This study suggests that
radiation therapy of skin
hemangioma increases the risk of further
melanoma, but we were not able to evidence a relation with the local dose. Nevertheless, childhood treated for
hemangioma should be considered at risk for developing
melanoma and suspicious pigmented lesions should be carefully evaluated even far from treated areas.