PowerPoint Presentation


A clinical impact study of dermatologists’ use of the 23- or 35-gene expression profile 
(GEP) tests to guide surgical excision and enhance management plan confidence

Aaron S Farberg, MD1, Kelli L Ahmed, PhD2, Briana B Rackley, PhD2, Jennifer J Siegel, PhD2, Brooke H Russell, PhD2, 

Jason H Rogers, MSc2, Sarah J Kurley, PhD2, and Matthew S Goldberg, MD2,3

1Baylor Scott & White Health System, Dallas, TX 2Castle Biosciences, Inc., Friendswood, TX 3Icahn School of Medicine at Mount Sinai, New York, NY

› The 23-gene expression profile (GEP) and 35-GEP tests are clinically available, objective ancillary
diagnostic tools that facilitate diagnosis of melanocytic lesions with ambiguous histopathology. The
tests use proprietary algorithms to provide results: suggestive of benign neoplasm; intermediate
(cannot rule out malignancy); or suggestive of malignant neoplasm with high accuracy.1-6

› Communication between the diagnosing dermatopathologist/pathologist and the treating clinician
is key to establishing appropriate patient management.7,8 There are circumstances when a
dermatologist may find additional diagnostic information helpful in determining excision and
follow-up actions.9,10

Background

Methods

Clinical impact

The majority of excision
decisions and follow-up
changes were aligned
with GEP results across
the uncertain scenarios.
There was also an
increase in management
plan confidence with GEP
results provided

›.

› Clinicians were invited for study participation based on prior use of diagnostic GEP testing (minimum 3
encounters with GEP results). Thirty-two board certified dermatologists participated in this Institutional Review
Board (IRB)-approved study. Clinicians were asked three questions per scenario: 1) How would you treat the
patient? No further treatment necessary, No further treatment necessary if lesion appears completely excised,
Excise <5 mm margins (narrow but complete), Excise ≥5 mm margins (but <1 cm), Wide local excision (Excise
≥1 cm; 2) Which follow-up schedule would you recommend? Every 12, 6, 3, or every month; 3) How
confident are you in this management plan? 1 (not confident), 2 (slightly confident), 3 (somewhat confident),
4 (fairly confident), 5 (completely confident).

› Clinical and diagnostic information for six uncertain patient scenarios was provided (Table 1). Diagnostic
information was taken from real-world pathology reports of melanocytic lesions and displayed in mock form
including the diagnosis and microscopic description. Clinical information was based on common clinical
situations that may alter patient treatment. GEP test results were either not provided (baseline), benign, or
malignant for each patient scenario.

Acknowledgments & Disclosures
ASF has served as a consultant for Castle Biosciences, Inc. KLA, BBR, JJS, BHR, JHR, SJK, and MSG are employee shareholders of
Castle Biosciences, Inc. The study was supported by Castle Biosciences, Inc. Presented at the Winter Clinical Dermatology
Conference - Hawaii® (WCH23), January 13-18, 2023, Kohala Coast, Hawaii (Encore presentation in part from ASDS 2022)
For more information: afarberg@castlebiosciences.com

Results

References

›GEP results can aid dermatologists in decision making to
achieve appropriate management plans

›Management changes, including surgical excisions and
follow-up frequency, were aligned with GEP results for these
uncertain clinical scenarios

›Scenario-specific survey results demonstrate that a
personalized approach can be achieved with GEP

Conclusions

Results

1. Clarke, L. E. et al. J Cutan Pathol 2015. 42 (4) 244–252. 2. Clarke, L. E. et al. Cancer 2017. 123 (4) 617–628. 3. Clarke, L. E. et al. Personalized Medicine
2020. 17 (5) 361–371. 4. Estrada, S. et al. SKIN 2020. 4 (6) 506–522. 5. Ko, J. S. et al. Cancer Epidem Biomar Prev 2017. 26 (7) 1107–1113. 6. Ko, J. S. et al.
Human Pathology 2019. 86 213–221. 7. Smith, Shane D. B., et. al. JAMA Dermatol. 2021. 157(9):1033-1034. 8. Cockerell, C. Dermatol Surg. 2018.
44(2):175-176. 9. Cockerell C, et al. Personalized Medicine. 2017. 14(2):123-130. 10. Farberg, A. et al. SKIN 2020. 4 (6) 523–533.

Scan or click here 
for more info

Here we present dermatologist management plans and confidence utilizing 
diagnostic GEP results in uncertain clinical and diagnostic scenarios 
›.

Excision Follow-up Confidence

GEP Result

A
v
e
ra

g
e

 %
 C

h
a
n

g
e

Benign Benign MalignantMalignant Benign Malignant

-50

50

0

100

D
e

c
re

a
se

In
c
re

a
se

Baseline

Figure 1. Overall clinical impact across all ambiguous scenarios

Figure 2. GEP results impact surgical excision planning and margin decisions

Figure 3. GEP results alter recommended follow-up frequency

› Clinical impact was assessed by calculating the mean percent of no change, increase in change, or
decrease in change relative to no GEP results (baseline) for each scenario and normalized to 100%.

› Surgical margins: When a malignant GEP result wass provided, there was an increase in surgical
treatment for most scenarios. When a benign GEP result was received, there was a decrease in
surgical management intensity in most scenarios.

Table 1. Ambiguous lesion scenarios from real-world pathology reports

Clinical Impression Diagnosis
Included excision 
recommendation

Cosmetic site Melanocytic neoplasm, atypical melanocytic proliferation No

Cosmetic site Dysplastic nevus with features of regression Yes

Personal history of melanoma Melanocytic neoplasm, atypical melanocytic proliferation No

Personal history of melanoma Melanocytic neoplasm, deep penetrating Yes

Comorbidities Atypical intraepidermal melanocytic proliferation (AIMP) Yes

High clinical suspicion Atypical intraepidermal melanocytic proliferation (AIMP) Yes

Malignant GEP

Baseline (no GEP)

Benign GEP

Malignant GEP Baseline (no GEP)Benign GEP

mailto:afarberg@castlebiosciences.com
https://castletestinfo.com/mypath-melanoma-diffdx-melanoma/scientific-references/
https://castletestinfo.com/mypath-melanoma-diffdx-melanoma/scientific-references/

	DD_01_036 Winter Clinical Hawaii 2023 poster survey v2 
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