62: Prospective validation of the integrated 31-gene expression profile test for cutaneous melanoma to select patients who may consider foregoing sentinel lymph node biopsy

Thursday, March 21, 2024

2:17pm – 2:27pm ET

Location: C102

Abstract Presenter(s)

JG

J. Michael Guenther, MD

Physician
St Elizabeth Physicians
Cincinnati, Ohio, United States

Author(s)

AW

Andrew Ward, PhD

Nurse Practictioner
Division of Surgical Oncology, University of Tennessee Medical Center
Knoxville, Tennessee, United States
BM

Brian Martin, PhD

Senior Scientist II
Castle Biosciences, Inc.
Friendswood, Texas, United States
RS

Rohit Sharma, MD, FACS

Surgical Oncologist
Marshfield Medical Center, United States
MY

Maki Yamamoto, MD

Physician
School of Medicine, University of California-Irvine, United States

Disclosure(s):

J. Michael Guenther, MD: Castle Biosciences: Speaker (Ongoing)

Introduction:

Sentinel lymph node biopsy (SLNB) is recommended for patients with cutaneous melanoma for those with >10% risk of having a positive node, considered for those with 5-10% risk, and not recommended when risk is < 5%. Estimating these risks using AJCC criteria results in 88% of SLNBs being negative. Identification of patients at low risk of SLN positivity could reduce the number of negative SLNBs performed. The integrated 31-gene expression profile test (i31-GEP for SLNB) combines the 31-GEP with clinical and pathological factors to identify patients with low-risk of SLN positivity who may potentially forego SLNB.

Methods:

The DecisionDx-Melanoma Impact on Sentinel Lymph Node Biopsy Decisions and Clinical Outcomes (DECIDE) study is a prospective, United States-based, multicenter study analyzing the effect of 31-GEP results and SLNB risk prediction on SLNB decisions in patients with T1-T2 cutaneous melanoma tested with the 31-GEP. The decision whether to perform an SLNB procedure was determined by the physician and patient. This analysis assessed 322 patients with all clinical data for analysis by the i31-GEP for SLNB. Patients with an i31-GEP for SLNB predicted risk < 5% were considered low-risk.

Results:

SLNB was performed in 43.5% (140/322) of patients with T1-T2 tumors. The overall SLNB positivity rate was 6.4% (9/140). Thirty-five patients (25.0%) undergoing SLNB had < 5% predicted risk of a positive SLN by the i31-GEP (n=11 T1a; 19 T1b; 4 T2a; 1 T2b). Of those with predicted risk ³5%, 8.6% (9/105) had a positive node, and of those with a predicted risk < 5%, none (0/35) had a positive node.

Conclusions:

In this prospective study, no patient with an i31-GEP for SLNB and predicted risk of < 5% had a positive SLN. The i31-GEP for SLNB identified a group of patients with T1-T2 cutaneous melanoma with < 5% risk of SLNB who should consider foregoing the procedure.

Learning Objectives:

Upon completion, participant will be able to understand how the integrated-31-gene expression profile test can identify patients with low risk of sentinel lymph node positivity.
Upon completion, participant will be able to describe the results of DECIDE, a prospective multicenter study to assess the effect of 31-GEP results on sentinel lymph node biopsy decisions.
Upon completion, participant will be able to understand how GEP testing can reduce unnecessary biopsies in patients with T1-T2 cutaneous melanoma.