Genomic Test Could Reduce Lymph Node Biopsy Surgery in Melanoma Patients

Accurately determining whether melanoma has spread to the lymph nodes is crucial for guiding treatment decisions, yet the standard procedure—sentinel lymph node biopsy—remains invasive, costly, and unnecessary for many patients. Now, researchers have developed a genomic test that predicts the likelihood of lymph node involvement using only tumor tissue from an existing biopsy.

Sentinel lymph node biopsy, the current standard for assessing melanoma spread, involves removing one or more lymph nodes under anesthesia for microscopic examination. Although effective, the procedure carries risks and side effects, including pain, swelling, and infection. Yet nearly 80% of patients who undergo the surgery are found to have no cancer in their lymph nodes.

Image: The genomic test measures eight gene activities in a melanoma tumor and combines this data with patient factors like age and tumor thickness (Photo courtesy of 123RF)

The genomic test, called the Merlin CP-GEP Test, developed by researchers at the Mayo Clinic (Rochester, MN, USA), in collaboration with SkylineDx (San Diego, CA, USA), measures the activity of eight genes within a melanoma tumor and combines this molecular data with patient-specific clinical factors such as age and tumor thickness. This information is used to estimate the likelihood that cancer cells have spread to nearby lymph nodes.

Importantly, the test analyzes tissue already collected during the initial tumor biopsy—meaning no additional surgical procedure or clinic visit is required. The Merlin CP-GEP Test offers a noninvasive alternative that could spare many from unnecessary surgery while maintaining diagnostic accuracy.

In the largest prospective study of its kind, a multicenter clinical trial that enrolled 1,761 patients with early- or intermediate-stage melanoma across nine U.S. cancer centers between 2021 and 2024. The results were striking: about 93% of people classified as low risk had no cancer in their lymph nodes, while roughly 25% of those in the high-risk group did. These findings suggest that the test can accurately distinguish which patients need further surgical evaluation and which can safely avoid it. The study, published in JAMA Surgery, demonstrates that the test could help thousands of melanoma patients avoid unnecessary surgery.

Researchers emphasize that melanoma progression is influenced by subtle molecular mechanisms, and translating these biological insights into clinical tools is transforming care. Future studies are now underway to explore how incorporating the Merlin CP-GEP Test into standard melanoma management could help predict recurrence risk and guide follow-up care, advancing the shift toward more personalized, data-driven oncology.

“Surgery will always be central to cancer care, but this study shows that sentinel lymph node surgery might be avoided for selected melanoma patients,” said Dr. Tina Hieken, co-principal investigator of the study. “This test lets us use a patient’s own tumor biology to guide care with true precision.”

Related Links:
Mayo Clinic
SkylineDx