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Mortality Appears to be Higher for Patients with Thicker Single Primary Melanomas than for Thicker Multiple Primary Melanomas

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Key Points

  • Researchers found no strong evidence of a difference in survival between single primary melanoma and multiple primary melanoma patients.
  • Patients with melanomas thicker than 4.00 mm had a much poorer survival compared to those with melanomas 1.00 mm or less.
  • Relative risk of death after a melanoma thicker than 4.00 mm was 4.6 times higher for single primary melanoma than for multiple primary melanoma.

Although overall mortality rates due to single primary melanomas and multiple primary melanomas appear to be similar, relative mortality for thicker single primary melanomas appears to be greater than that for thicker multiple primary melanomas, according to a study by Anne Kricker, PhD, of the University of Sydney, Australia, and colleagues. The study was published online today in JAMA Dermatology.

A total of 2,372 patients with single primary melanoma and 1,206 patients with multiple primary melanoma participated in the large, population-based Genes, Environment, and Melanoma (GEM) study. Melanoma thickness was the main determinant of mortality; other independent predictors were ulceration, mitoses, and scalp location.

GEM Study Results

After adjustment for these predictors, the researchers found little difference in mortality rates between multiple primary melanoma and single primary melanoma (hazard ratio [HR] = 1.24, 95% confidence interval [CI] = 0.91–1.69, P = .18).

However, melanoma thickness had a significant effect on mortality rates, according to the study results. Patients with melanomas thicker than 4.00 mm had a much poorer survival (HR = 7.68, 95% CI = 4.46–13.23, P < .05) compared to those with melanomas 1.00 mm or less. In addition, the relative risk of death after a melanoma thicker than 4.00 mm was 4.6 times higher for single primary melanoma than for multiple primary melanoma.

“We found no strong evidence of a difference in survival between single primary melanoma and multiple primary melanoma patients despite the evidence of other researchers and suggestions that multiple primary melanoma may have a less aggressive biology than single primary melanoma … to our knowledge, we report for the first time a greater increase in the risk of death with increasing tumor thickness for single primary melanoma than for multiple primary melanoma,” the authors concluded.

This study was supported by grants from the National Cancer Institute at the National Institutes of Health and by a Health Research Infrastructure Award from the Michael Smith Foundation. The authors reported no potential conflicts of interest.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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