medwireNews: Compared with the general population, childhood cancer survivors have a twofold increased risk for melanoma, findings indicate.
Furthermore, “survival was substantially worse” for those who developed invasive melanoma versus other survivors, report Seth Rotz (Cleveland Clinic Children’s Hospital, Ohio, USA) and co-investigators in the Journal of Clinical Oncology.
They analyzed data from the Childhood Cancer Survivor Study cohort, which followed up 5-year survivors of childhood cancer diagnosed in the USA and Canada between 1970 and 1999.
Among the 25,716 participants included in the current analysis, 177 melanomas were diagnosed in 160 survivors at a median of 26.4 years from their pediatric cancer diagnosis. The majority (n=110) of the melanomas were invasive cutaneous, while 62 were in situ cutaneous and five were ocular.
The 40-year cumulative incidence of any melanoma was 1.1% among all participants and 1.5% among those who had received a cumulative radiation dose of 40 Gy or more.
The standardized incidence ratio for invasive skin or ocular melanoma was 2.0 for childhood cancer survivors versus the general population. And the absolute excess risk for survivors was 9.1 cases per 100,000 person–years.
Rotz and colleagues also evaluated risk factors for cutaneous melanoma, finding that the risk was significantly greater for participants who had received a cumulative radiation dose of at least 40 Gy to the corresponding body region, with a hazard ratio (HR) versus no radiation of 2.0 after adjusting for multiple factors.
The risk was similarly increased for participants who received a cumulative cyclophosphamide equivalent dose of at least 20,000 mg/m2 versus no treatment with alkylating agents, and for those treated with any dose of bleomycin versus none, with respective significant HRs of 1.9 and 2.2.
“Alkylating agents have been associated with the development of both solid and hematologic SMNs [subsequent malignant neoplasms] among survivors,” say the researchers. “However, bleomycin, which acts by inducing DNA strand breaks, has not historically been associated with SMNs and this relationship bears further investigation.”
Finally, they report that “a multivariable model with attained age as the time scale and adjusted for sex” showed a significant association between invasive melanoma at any site and an increased risk for death, with an HR of 2.4.
In conclusion, Rotz et al say that “[f]uture dermatologic screening practices should consider the risks of melanoma among childhood cancer survivors and the relationship to these exposures.”
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