The number of primary melanomas is not an independent risk factor for mortality.
The difference in outcomes between people with multiple primary melanomas (MPMs) and a single primary melanoma (SPM) has not been established.
To compare 10-year melanoma-specific mortality and overall mortality between people with MPMs and SPM, researchers drew from the Melanoma Patterns of Care study, a population-based observational analysis of residents in the state of New South Wales, Australia, who had a melanoma reported to the state cancer registry over 12 months in 2006-2007, and were followed up until 2018, for a median of almost 12 years.
The researchers performed logistic regression analyses to assess 10-year melanoma-specific mortality differences between the two groups.
Of 3404 people included in the analysis, 2830 had an SPM and 574 developed MPMs during follow-up.
On multivariable regression adjusted for pathologic characteristics of the thickest lesion in the MPM group, no significant differences were seen in 10-year melanoma-specific mortality between the two groups (odds ratio [OR], 0.85, 95% CI; 0.58-1.24; P = .40).
Sensitivity analyses adjusted for parameters of the first primary melanoma among patients with MPMs revealed similar findings (OR, 1.34; 95% CI, 0.92-1.96, P = .12).
On multivariable analysis using data from the thickest lesion, factors independently associated with melanoma-specific mortality were male sex, disadvantaged socioeconomic status (based on location of residence), and Breslow thickness.
Factors independently associated with 10-year overall mortality were like those seen in other studies and included sex, Breslow thickness, ulceration status, and socioeconomic disadvantage.
"The results of our study suggest that the number of primary melanomas is not an independent risk factor for mortality," the researchers concluded. "In addition, the detection of melanoma at an early stage (with a thin Breslow thickness) rather than an intrinsic biologic factor remains the biggest influence on melanoma mortality after diagnosis of one or more melanomas."
Corresponding author Serigne N. Lo, PhD, of the Melanoma Institute Australia, led the research. The study was published September 13, 2023, in the Journal of the American Academy of Dermatology.
No adjustments for treatment modality were made in the study, and at baseline survey, effective systemic treatments for melanoma were not available.
This study was supported by the Australian National Health and Medical Research Council, Cancer Institute New South Wales, and the New South Wale State Government via a grant to the New South Wales Melanoma Network. Additional support was provided by Melanoma Institute Australia and the New South Wales Melanoma Network.
Lead image: Centers for Disease Control and Prevention
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Cite this: Does the Number of Primary Melanomas Affect Survival? - Medscape - Sep 21, 2023.