De novo melanomas, which arise from clinically normal skin with no associated nevus, may be more aggressive than nevus-associated melanomas, a study published in the Journal of the National Cancer Institute has shown.1

Approximately 20% to 30% of melanomas are associated with a nevus, while the majority of melanomas are de novo. Researchers sought to examine whether these forms of melanomas are associated with differences in patient survival and clinical and histopathologic features.

For the study, investigators analyzed data from 2 prospective cohorts, which included a total of 2149 patients, conducted at NYU Langone Medical Center in New York City. Associations between melanoma classification and features were tested in the first cohort of 1024 patients and then replicated in the second cohort of 1125 patients.

Results showed that in the first cohort, de novo melanomas were associated with tumor thickness greater than 1.0 mm (odds ratio [OR] = 1.96; P <.001), ulceration (OR, 1.65; P =.02), nodular subtype (OR, 3.26; P =.001), greater than stage I (OR, 2.35; P <.001), and older age (OR = 1.64; P =.004).

Researchers also found that de novo melanomas were associated with shorter overall survival compared with nevus-associated melanomas (hazard ratio [HR], 1.63; 95% CI, 1.22-2.18; P <.001).

In the second cohort, de novo melanomas were again significantly associated with the aforementioned clinical and histopathologic features (all P <.001), as well as shorter overall survival (HR, 2.52; 95% CI, 1.78-3.56; P <.001).

Of note, the study demonstrated a statistically significantly poorer survival among male patients with de novo melanomas vs female patients with de novo melanomas; however, there was no difference in survival between patients of the opposite sex among those with nevus-associated lesions.

“This classification scheme may also provide a useful framework for investigations into sex differences in melanoma outcomes,” the authors conclude.

Reference

1. Cymerman RM, Shao Y, Wang K, et al. De novo vs nevus-associated melanomas: differences in associations with prognostic indicators and survival. J Natl Cancer Inst. 2016 May 27. doi: 10.1093/jnci/djw121. [Epub ahead of print]