Research on lymphatic mapping and sentinel-node biopsy has confirmed that these techniques significantly prolong patients’ disease-free and melanoma-specific survival over traditional “watch and wait” techniques.
This method of detecting melanoma metastasis to the lymph nodes allows doctors to determine which patients actually have nodal metastasis and may benefit from having their non-sentinel lymph nodes removed, which consists of approximately 20 percent of patients, while sparing the surgery for the many patients it will not benefit.
The study, published in the New England Journal of Medicine, evaluated outcomes of 2,001 melanoma patients at 10 years of follow-up.
One important finding was that the thickness of the initial melanoma tumor relates to the effectiveness of these treatments in managing nodal and other metastases.
Patients with primary melanoma tumors of intermediate thickness (1.20 to 3.5 millimeters thick) who had sentinel-node biopsies with immediate complete removal of the lymph nodes if the sentinel node contained cancer cells had an overall disease-free survival of 71.3 percent compared to 64.7 percent for those whose nodes were observed without sentinel biopsy.
The research also found that sentinel-node biopsy prolonged distant disease-free survival and melanoma-specific survival for patients with lymph node metastasis from primary melanomas of intermediate thickness.
A mixture of blue dye and radioactive tracer was injected into the tissues around the primary tumor to find the lymphatic channels that lead to the first tumor-draining lymph node. The dye-isotope mixture follows the same lymphatic path used by the melanoma cells to spread to the sentinel node. The sentinel node is removed and examined by microscopy. If tumor cells are not found in the sentinel node it is highly unlikely that there will be tumor in other non-sentinel nodes and further nodal surgery is considered unnecessary. If cancer cells are found in the sentinel node, all other lymph nodes in the nodal group are removed.
Although some patients with thick primary tumors benefit from having their lymph nodes removed, the findings suggest that the timing of the intervention is not as crucial for them as it is for patients with intermediate thickness primary tumors. Not enough patients with thin melanomas were in this trial to permit conclusions on their benefit from the technique.
