New Study May Help Refine Sentinel Node Biopsy Decisions for Melanoma Patients
A new study presented at the Society for Melanoma Research annual meeting could influence how early-stage melanoma patients are selected for sentinel node biopsy, a surgical procedure often used to determine if melanoma has spread to the lymph nodes. The MERLIN_001 trial was designed to evaluate whether a new gene expression profile test could help doctors more accurately predict which patients are at low risk of lymph node involvement, potentially sparing them from unnecessary surgery.
Sentinel node biopsy is a common staging procedure for patients with melanoma, especially those with tumors that are at least 0.8 millimeter thick as measured under the microscope. Current guidelines routinely recommend the procedure for patients with a 10% or greater risk of lymph node metastasis, and in many centers including Moffitt Cancer Center, most healthy patients with at least a 5% risk of having melanoma in their sentinel node are considered for the surgery. But whether the threshold used is 5% or 10%, that still means that most patients who undergo the sentinel node biopsy procedure won’t be found to have cancer in their lymph nodes. So, surgeons and researchers have been looking for better ways to predict who truly needs to undergo the surgery.
The test that was evaluated in the MERLIN_001 trial, called the CP-GEP (Clinicopathologic and Gene Expression Profile) test, was developed specifically to identify patients with either a low risk or a high risk of having a sentinel node metastasis, but a large study was needed to see if the CP-GEP test could identify patients’ risk precisely enough to be clinically useful. The test combines two clinical factors – the primary melanoma tumor’s thickness and the patient’s age – with genetic information from the patient’s tumor biopsy.
The results showed that the test successfully identified patients with a less than 10% risk of lymph node metastasis, providing doctors with another tool for making more personalized treatment decisions. For example, patients with clinical stage IB tumors (T1b and T2a in the current staging system) who were classified as low risk by the CP-GEP test had a 6.4% chance of having a positive sentinel node, compared to 18.7% (three times more) for high-risk cases.
Vernon Sondak, MD
“This test could be a valuable for some patients with early-stage melanoma, but for many patients in whom a 5% risk of having a positive node is the appropriate threshold for surgery, the test won’t be helpful,” said Vernon Sondak, MD, lead investigator of the MERLIN_001 trial and chair of the Cutaneous Oncology Department at Moffitt, “Still by appropriately using this test for patients in whom a higher risk threshold is appropriate, we can reduce the number of patients who need to undergo sentinel node biopsy, which is an invasive procedure done under general anesthesia.”
The results of this trial will help doctors provide more personalized treatment for melanoma patients. With this new information, doctors can have clearer, more informed conversations with their patients about treatment options. Even for patients who don't use the gene expression test to guide their decisions, the trial will help them better understand why a sentinel node biopsy might still be necessary.
