The brave new world of melanoma gene expression markers
By Warren R. Heymann, MD
May 14, 2016
Epidermolysis bullosa nevi (EBN) are clinically alarming lesions that may display “pseudomelanoma” features histologically. Changes within these lesions may be disconcerting, necessitating repeated biopsies. Any advances to predict biologic behavior would be welcome.
Ahn et al report the case of a 12 year-old girl with EB simplex, who they had followed since age 4 with an EBN. At age 9 a biopsy of the lesion demonstrated features consistent with an atypical nevus. When she was 12 the lesion has recently changed with dermatoscopy suggesting malignant transformation. A repeat biopsy showed an atypical compound nevus with areas of regression. The authors utilized the Myriad myPath gene expression test score (for 23 melanoma genes) that the lesion was benign. The decision was made to manage the lesion with conservative observation (1).
Last week we listened to a presentation from Castle Bioscience about their similar test of 31 melanoma genes. * They score patients as level 1 (low risk) or level 2 (high risk). Unquestionably, even more novel, potentially more precise techniques are being developed at breakneck speed. For example, long non-coding RNAs (lncRNAs) cannot be translated into proteins, but are aberrantly expressed in cancers, affecting apoptosis, cell regulation, and epigenetics .Guo et al have linked lncRNAs to melanoma survival (2).
These are exciting times in the melanoma world, both diagnostically and therapeutically. Despite these advances, many questions remain. For patients with melanoma, should we be testing patients that are classically low-risk with these tests? For example, I view my own melanoma (Breslow 0.33 mm, no mitoses) as low risk. Do I really want to know if my score is a level 2.? What would I do then? Go for PET-CT scans every 6 months? Would my insurance pay for it? I could foresee ample worry with little benefit. One could argue that with new immunotherapeutic and targeted therapies, the earlier anything is detected, the better. I agree with that completely, however, at this point, perhaps such testing should be performed for only those patients for whom we might otherwise consider sentinel node mapping (> 1mm, or thin lesions that are ulcerated or display mitotic figures).
This article, on the other hand, points to a very appropriate use of genomic technology. Be it an EBN, an atypical Spitz nevus, or nevoid melanoma, having accurate prognostication is the key to proper management. I have little doubt that before the next decade, advances in molecular studies will supplant the use of sentinel node testing and be used routinely in the diagnosis of borderline, atypical melanocytic lesions.
1. Ahn JW, et al. Melanoma gene expression markers for surveillance of epidermolysis bullosa nevi malignant transformation. JAMA Dermatology 2016; 152: 584-6.
2. Guo L, et al. A novel integrative approach to identify lncRNAs associated with the survival of melanoma patients. Gene 2016; 10: 585: 216-20.
I have no conflict of interest with either Castle Bioscience or Myriad Genetics.
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