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Cohort study finds 8% risk for second primary melanoma within 5 years

Researchers identified an 8% 5-year risk for second primary melanoma in a cohort of patients with melanoma and confirmed the utility of total body photography and digital dermatoscopic documentation in follow-up visits.

The cohort included 977 patients with recently diagnosed primary cutaneous melanoma of any stage who underwent clinical and dermatoscopic examinations for up to 5 years. The male-female ratio was 1.1:1, and mean patient age at baseline was 54.69 years; 77.4% of patients had invasive melanoma and 22.6% had in situ melanoma. Invasive melanomas had a mean Breslow thickness of 1.92 ± 1.55 mm.

At the time of analysis, 807 patients had completed 1 year of follow-up, 560 patients completed 2 years, 349 patients completed 3 years, 172 patients completed 4 years and 114 patients completed 5 years; 131 patients were within their first year of follow-up.

One hundred eighty-five patients died, of which 145 deaths were associated with melanoma; 51 patients were lost during follow-up.

Forty-six patients (4.7%) developed a second primary melanoma, four patients developed a third and two developed a fourth during the study period.

The annual risk for a second primary melanoma was 2.46% within the first year, 1.61% the second year, 1.43% the third year, 1.43% the fourth year and 1.17% the fifth year.

The cumulative proportion of patients who did not develop a second primary melanoma in the study period was 92%, so the risk for developing a secondary primary melanoma within the first 5 years was 8%.

About two-thirds of new melanomas were in situ and nearly a third were invasive.

Researchers identified three strong predictors of second primary melanoma: nevus count, phototype and occupational sun exposure. Family history was associated with a higher probability of second primary melanoma, but it was marginally not significant.

“Our study also highlights the usefulness of [total body photography] and sequential [digital dermatoscopic documentation] as integral parts of follow-up visits of patients with melanoma history,” Aimilios Lallas, MD, MSc, PhD, of the first department of dermatology at Aristotle University, Greece, and colleagues wrote. “Of all new melanomas, 67.3% were in situ and the remaining 32.7% were thinner than 1 mm, suggesting a high efficacy of the applied monitoring protocol in early [second primary melanoma] diagnosis.” – by Abigail Sutton

Disclosures: The authors report no relevant financial disclosures.