Comparing Two Gene Expression Profile Tests to Standard of Care for Identifying Patients With Cutaneous Melanoma at...

The National Comprehensive Cancer Network (NCCN) Guidelines for cutaneous melanoma (CM) recommend avoiding sentinel lymph node biopsy (SLNB) when the positivity risk is <5%, considering SLNB when the risk is 5-10%, or offering SLNB when the risk is >10%. Most patients undergoing SLNB have a negative result, showing that reliance upon the American Joint Committee on Cancer (AJCC) T-stage alone results in most patients undergoing an unnecessary, negative, unreliable, invasive procedure.

Two gene expression profile (GEP) tests, the CP-GEP and the 31-GEP, have been developed to identify patients at low risk of SLN positivity who may consider avoiding SLNB. We analyzed the accuracy of the CP-GEP and 31-GEP in identifying patients with <5% risk of SLN positivity across the five validation studies of the CP-GEP and four validation studies of the 31-GEP in T1-T2 tumors.

Patients considered low risk by the CP-GEP had an SLN positivity rate of 6.2%, higher than the risk threshold of 5% used by the NCCN to guide SLNB decisions. In contrast, patients considered low risk by the 31-GEP or i31-SLNB had a 2.8% SLN positivity rate, a substantial improvement over AJCC-staging guidance.

Overall, the CP-GEP did not perform as well as AJCC, while the 31-GEP performed better than AJCC.