New Technique Helps Determine Spread of Melanoma
UCLA professors Dr. Donald Morton and Dr. Alistair Cochran recently led a long-term research study with promising results for techniques used to detect signs of melanoma metastasis. The study confirmed that lymphatic mapping and sentinel-node biopsy are ideal methods for doctors to quickly determine whether patients need to have their lymph nodes removed or if they can be spared the surgery.
The study notes that 20% of patients benefit from having their non-sentinel lymph nodes removed, and 80% cannot benefit from the surgery. By detecting the degree of melanoma metastasis in the lymph nodes of the patient, the 80% who will not benefit can be spared the stress of surgery, the cost, and the associated complications. Moreover, this method has shown to prolong patients’ survival of the disease and melanoma over the traditional treatment based on observation or “watch and wait”.
At the time of melanoma diagnosis, the procedure can be done to measure if any tumor cells have spread to the sentinel lymph node. This technique works through lymphatic testing with blue dye by a radioactive tracer. The mixture that is injected into tissue around the tumor will take the same lymphatic path as the melanoma cells, making it easy to find the lymph node most connected to the melanoma. When the sentinel node is found they will remove just the one to examine it and test for melanoma cells. If this one node is free of tumor cells, it is very unlikely that cells have spread to other lymph nodes. Extracting all the lymph nodes from the patient’s body in this case would be unnecessary. If tumor cells are found in the sentinel lymph node however, immediate removal of nodes in that group is crucial.
The long-term research also found that the thickness of the melanoma tumor affects the impact of these treatments on nodal management. Patients with tumor thickness of 1.2-3.5 millimeters had a 71.3% disease-free survival after the sentinel-node biopsy and lymph node removal. Patients with similar thickness who did not have the biopsy showed a 64.7% disease free survival. Researchers also noted that sentinel-node biopsy prolonged survival without disease spreading to other organs or development of more metastases for patients with tumors of this thickness.
Image: Paul Garland