PowerPoint Presentation


31-gene expression profile assessing metastatic risk in 
melanoma patients: Issues impacting patient selection 

Ryan M. Svoboda, MD MS1, Alex M. Glazer, MD2, Darrell S. Rigel, MD MS3* 

Background 

Objective       

Methods 

Results 

Limitations 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Conclusions 

1National Society for Cutaneous Medicine, New York, NY 2Division of Dermatology, University of Arizona, Tucson, AZ 3Ronald O. Perelman Dept. of Dermatology, NYU Medical Center, New York, NY 
 

• Genetic evaluation of melanoma plays an increasingly important 
role in clinical practice 

• A 31-gene expression profiling (31-GEP) test (Decision-DX-
Melanoma, Castle Biosciences, Inc., Friendswood, TX) to predict 
metastatic risk in cutaneous malignant melanoma (CMM) has been 
validated and is available for clinical use 

• The impact of the results of this test on clinical decision making has 
been studied, but little is known about which clinical factors impact 
dermatologists’ decision to utilize the test 

• To determine which factors impact the decision to utilize the 31-
GEP test for metastatic risk stratification in CMM patients 

*Disclosures: Dr. Rigel serves as a consultant to and on the advisory board for Castle Biosciences. Drs. Svoboda and Glazer participated in Research Fellowships funded in part by Castle Biosciences. 

• 181 dermatologists attending the 2017 Winter Clinical Dermatology 
Conference-Hawaii® completed a series of questions based around 
four clinical vignettes using an audience response system 

• Vignettes assessed the impact of three factors on the decision to 
order the 31-GEP test: 

• Breslow thickness 
• Ulceration 
• Sentinel lymph node biopsy (SLNBx) status 

• Chi-squared tests were used to compare the proportion of 
respondents who would order the test at baseline and in the 
presence of ulceration and a negative SLNBx for each Breslow 
thickness 

Patient 
Vignette 

Age, 
Gender 

Melanoma 
Location 

Breslow 
Thickness 

1 45, Female Right leg 0.76 mm 

2 42, Male Right back 0.50 mm 

3 35, Male Right arm 0.26 mm 

4 72, Female Right neck 2.10 mm 

Clinical Characteristics of Patient Vignettes 

• Subjects were given a brief introductory lecture on the background of the 31-GEP test immediately prior to the survey; this 
may have introduced bias 

• Sample may not be representative of the overall population of practicing United States dermatologists 

• A majority of Dermatologists in this sample would order the 31-GEP test for melanomas of any Breslow thickness in the 
presence of ulceration and melanomas with Breslow thickness ≥ 0.50 mm in the absence of ulceration 

• Despite the fact that 2/3rds of CMM patients who develop metastases initially have a negative SLNBx, negative SLNBx 
status does not seem to be a significant stimulus to ordering the test 

Percentage of Dermatologists Who Would Order 31-GEP Test in Different Clinical Scenarios 

*statistically  
  significant  
 
**p-value comparing  
proportion who would order  
test at baseline and in  
presence of ulceration or  
SLN negative status for given 
thickness 

Breslow 
Thickness 

 
0.26 mm 

 
0.50 mm 

 
0.76 mm 

 
2.1 mm 

 
p-value* 

Non-ulcerated 22% 78% 61% 74% <0.001 

Ulcerated 67% 87% 80% 72% <0.001 

Percent of Sample Who Would Use 31-GEP Test to Predict Metastatic Risk in Malignant Melanoma 

*Using chi-squared test to compare the proportion  who would order the 31-GEP test at each Breslow thickness