(HealthDay News) — Patients with stage III or IV melanoma who have not received treatment with BRAF inhibitors remain at risk for developing new primary melanomas (NPMs), although the incidence rates are lower than those observed in studies of dabrafenib and vemurafenib, according to research published online Dec. 2 in the Journal of Clinical Oncology.
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Lisa Zimmer, MD, of the University Duisburg-Essen in Germany, and colleagues followed a large cohort of patients with stage III or IV melanoma, who were not treated with a BRAF inhibitor, to assess the background incidence of spontaneous NPMs.
The researchers found that the cumulative incidence rate of NPMs after diagnosis of stage III melanoma was 1.2% (95% confidence interval [CI], 0.86% to 1.51%) at 6 months, 1.8% (95% CI, 1.44% to 2.26%) at 1 year, and 5.9% (95% CI, 5.08% to 6.74%) at 10 years.
The cumulative incidence rate of NPMs after diagnosis of stage IV melanoma was 0.2% (95% CI, 0.07% to 0.36%) at 3 months, 0.3% (95% CI, 0.15% to 0.51%) at 6 months, and 0.4% (95% CI, 0.25% to 0.7%) at 1 year. A higher incidence of NPMs was observed in patients with stage III/IV melanoma who were male or who had a history of multiple primary melanomas.
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“Patients with stage III and stage IV melanoma remain at risk for development of further primary melanomas, particularly if they have a history of multiple primary melanomas before stage III or IV disease,” the researchers wrote. “Although the incidence rates are lower than those observed in the studies of dabrafenib and vemurafenib, the results must be compared with caution because of the more frequent and thorough dermatologic assessments in the BRAF inhibitor studies.”
Several researchers disclosed financial ties to pharmaceutical companies, including manufacturers of BRAF inhibitors.