Factors Affecting Dermatologists’ Use of a 31-Gene Expression Profiling Test as an Adjunct for Predicting Metastatic Risk in Cutaneous Melanoma

May 2018 | Volume 17 | Issue 5 | Original Article | 544 | Copyright © May 2018

Ryan M. Svoboda MD MS,a Alex M. Glazer MD,b Aaron S. Farberg MD,c and Darrell S. Rigel MD MSd

aNational Society for Cutaneous Medicine, New York, NY bUniversity of Arizona, Tucson, AZ cIcahn School of Medicine at Mount Sinai, New York, NY dNYU School of Medicine, New York, NY

decision-making in smaller, lower stage tumors. Since larger, higher-stage tumors are typically treated more aggressively according to available guidelines, these smaller tumors are the lesions where differentiating between less-aggressive and more-aggressive tumor biology becomes essential. However, it is unclear why SLN-negativity did not have a greater magnitude of impact on the decision to perform the assay. Despite the minimal impact of SLNBx results on the decision to order the 31-GEP test, in a patient with no a priori SLNBx results, a majority of respondents stated that 31-GEP test results would impact their decision of whether to recommend a SLNBx. This is consistent with a prior study by Farberg et al in which Dermatology residents were queried as to whether Class 1 or Class 2 results would alter their likelihood of recommending SLNBx.5 Taken together, these two studies suggest that in low-stage CMM, the results of the 31-GEP test have a significant and appropriate impact on management while remaining within the context of established guidelines. More research is needed to determine the actual incidence of SLNBx positivity in the subpopulations of Stage T1b CMM with Class 1 and Class 2 31-GEP results. Limitations of this study include the fact that the sample of dermatologists attending an academic conference may not be representative of the larger population of practicing United States dermatologists. Additionally, the survey format of the study, while providing insight into some of the factors considered by dermatologists when ordering the 31-GEP test, did not include all potential factors and did not allow discernment as to why SLN-negative status did not have a significant influence on the decision to order the test. 


The presence of ulceration and Breslow thickness ≥0.5 mm appear to be the most influential factors found in this study influencing the decision to order the 31-GEP test in patients with CMM. Despite the fact that two-thirds of CMM patients who develop metastases initially have a negative SLNBx, SLN-negative status does not seem to be a significant stimulus to ordering the test. Future studies should aim to understand the reasons for this and should also focus on uncovering other potential influences on the decision to utilize the assay. 


Dr. Rigel served as a consultant to Castle Biosciences Inc. Dr. Farberg served on an Advisory Board for Castle Biosciences, Inc. Drs. Glazer and Svoboda participated in a research fellowship, which was partially funded by Castle Biosciences Inc. 

Funding Sources: 

This study was funded in part by a grant from Castle Biosciences Inc. 


  1. Coit DG, Thompson JA, Algazi A, et al. Melanoma, Version 2.2016, NCCN Clinical Practice Guidelines in Oncology. J Natl Compr Cancer Netw. 2016;14(4):450-473. 
  2. Berger AC, Davidson RS, Poitras JK, et al. Clinical impact of a 31-gene expression profile test for cutaneous melanoma in 156 prospectively and consecutively tested patients. Curr Med Res Opin. 2016;32(9):1599-1604. 
  3. Morton DL, Thompson JF, Cochran AJ, et al. Final trial report of sentinel-node biopsy versus nodal observation in melanoma. NEJM. 2014;370(7):599-609. 
  4. Morton DL, Thompson JF, Cochran AJ, et al. Sentinel-node biopsy or nodal observation in melanoma. NEJM. 2006;355(13):1307-1317. 
  5. Farberg AS, Glazer AM, White R, Rigel DS. Impact of a 31-gene Expression Profiling Test for Cutaneous Melanoma on Dermatologists’ Clinical Management Decisions. .J Drugs Dermatol. 2017;16(5):428-431. 
  6. Ferris LK, Farberg AS, Middlebrook B, et al. Identification of high-risk cutaneous melanoma tumors is improved when combining the online American Joint Committee on Cancer Individualized Melanoma Patient Outcome Prediction Tool with a 31-gene expression profile-based classification. J Am Acad Dermatol. 2017;76(5):818-825.e813. 
  7. Gerami P, Cook RW, Russell MC, et al. Gene expression profiling for molecular staging of cutaneous melanoma in patients undergoing sentinel lymph node biopsy. J Am Acad Dermatol. 2015;72(5):780-785.e783. 


Ryan M. Svoboda MD MS rmsvoboda@gmail.com