Muller C, et al. - In this study, researchers analyzed to define the risk factors of subsequent melanomas. They observed internal factors like family history and genetic variants, the number of nevi and actinic damage on the back more suitable for the development of subsequent melanomas as compared to skin phototype or hair color. Cases with multiple nevi were found younger at the time of the diagnosis of their first melanoma. This conclusion appeared helpful in distinguishing person at increased risk of exhibiting multiple primary melanomas.

Methods

• From January 1, 1968, to March 16, 2015, 1648 candidates with histologically verified cutaneous melanoma diagnosed were recruited from a tertiary referral center as part of the Molecular Markers of Melanoma study.
• They sequenced CDKN2A in 514 and MC1R in 953 cases.
• They examined the data from March 7, 2008, to March 25, 2015.
• Phenotypic characters and internal and external risk factors for the development of a second, third, or fourth melanoma were the main outcomes and measures .

Results

• They enrolled 1648 subjects (53.6% men; mean [SD] age, 54 [15] years) involving 1349 with single and 299 with multiple primary melanoma.
• They observed 57 (15) years for the single-melanoma and 62 (14) years for the multiple-melanoma groups as the mean (SD) age at recruitment.
• By using multivariate logistic regression analysis they noted family history (odds ratio [OR], 1.76; 95% CI, 1.22-2.55; P=.006), CDKN2A high-risk mutations (OR, 4.03; 95% CI, 1.28-12.70;P =.02), and high numbers of nevi as a phenotypic risk factor (ORs, 2.23 [95% CI, 1.56-3.28, P < .001] (from the internal risk factors) for 20-30 smaller nevi and 2.56 [95% CI, 1.50-4.36; P=.003] for 20-30 larger nevi) were significantly correlated with the risk of developing a subsequent primary melanoma.
• They also found nonmelanoma skin cancer (OR, 2.57; 95% CI, 1.84-3.58; P < .001) and symptoms of actinic skin damage, especially on the back (ORs, 1.91 [95% CI, 1.12-3.25; P =.04] for freckling and 1.92 [95% CI, 1.29-3.08; P =.007] for solar lentigines) as increased risk factors for subsequent melanoma.
• All the factors were also observed linked to an earlier development of the second melanoma.
• Cases with 3 melanomas were recorded with developed second melanoma earlier than those with only 2 melanomas (mean [SD] age, 55 [15] years for those with 2 primary melanomas; 52 [15] years for those with 3 primary melanomas).
• No significant associations were observed in these models among time spent outdoors, solarium use, outdoor occupation, and hair color.