Sentinel-node Biopsy Plays Important Role in Melanoma
According to a study published in the New England Journal of Medicine, sentinel-node biopsy provides prognostic information in patients with intermediate-thickness melanoma, and may lead to improved survival in patients who are found to have a positive sentinel node.
Melanoma is a type of skin cancer that often begins in the form of a mole. Melanoma is considered an aggressive type of cancer, which has led physicians and researchers to promote active screening measures of individuals, particularly those with light skin, moles, and/or those who have spent a lot of time in the sun. If melanoma is detected early, prior to spread, the cure rates are high. However, once melanoma has spread to distant sites in the body, long-term survival remains dismal.
Selecting the most appropriate treatment for melanoma requires accurate assessment of the extent of the cancer. Sentinel nodes are the first lymph nodes to which cancer is likely to spread. Sentinel lymph node biopsy involves the removal of these nodes. An advantage of this procedure is that if no evidence of cancer is found in the sentinel node(s), patients are considered node-negative and are spared the effects of more extensive lymph node surgery.
To evaluate patient outcomes following sentinel-node biopsy, researchers conducted a clinical trial among 1,269 patients with intermediate-thickness (1.2 to 3.5 mm) melanoma. After surgery to remove the melanoma, patients were assigned to one of two groups. One group had sentinel-node biopsy, with immediate surgery to remove more lymph nodes if the sentinel node was positive. The other group was observed and underwent lymph node surgery only after lymph nodes became enlarged.
- Sentinel-node biopsy revealed very small areas of cancer in the lymph nodes in 16% of patients. These patients had an average of 1.4 involved lymph nodes. Patients with a positive sentinel-node biopsy had worse five-year survival than patients with a negative sentinel-node biopsy (72% vs. 90%).
- 15.6% of patients in the observation group eventually had cancer detected in the lymph nodes. These patients had an average of 3.3 involved lymph nodes.
- Among patients with involved lymph nodes, survival was better among patients in the sentinel-node group than among patients in the observation group. Five-year survival was 72% among patients who had a positive sentinel-node biopsy followed immediately by more extensive lymph node surgery, and 52% among patients who had lymph node surgery only after lymph nodes became palpable.
The researchers conclude that “In patients with primary melanomas that are 1.2 to 3.5 mm in thickness, sentinel-node biopsy should be preferred to observation.”
Reference: Morton DL, Thompson JF, Cochran AJ et al. Sentinel-Node Biopsy or Nodal Observation in Melanoma. New England
Journal of Medicine. 2006;355:1307-17.
Sentinel Lymph Node Spread in Early Melanoma
According to a recent article published in the Annals of Surgical Oncology, even patients with early melanomas (less than 1.0 mm thick) have a risk of cancer spread to local lymph nodes and should consider testing of the sentinel node.
Melanoma is a type of skin cancer that often begins in the form of a mole. Melanoma is considered an aggressive type of cancer, which has led physicians and researchers to promote active screening measures of individuals, particularly those with light skin, moles and/or those who have spent a lot of time in the sun. If melanoma is detected early, prior to spread, the cure rates are high. However, once melanoma has spread to distant sites in the body, long-term survival remains dismal.
Physicians continue in their attempt to ensure that patients diagnosed with early-stage melanoma have the least risk possible for a cancer recurrence. Therefore, some physicians have advocated the testing of a sentinel lymph node to improve rates of detection of cancer spread in early melanoma. Often, the site of initial cancer spread in melanoma is local lymph nodes; the sentinel lymph node is the single lymph node to which the cancer is initially most likely to spread. Therefore, testing of the sentinel lymph node for cancer cells is considered a good predictor of the chance that the cancer has spread from its site of origin. If cancer cells are not detected in the sentinel lymph node, the patient is considered to have cancer that has not spread. However, if cancer cells are detected in the sentinel lymph node, patients typically undergo the removal of several lymph nodes, as well as further screening to detect possible cancer spread elsewhere in the body. The issue that remains controversial in sentinel lymph node testing is the precise stage at which the testing is done.
Researchers from several institutions recently conducted a clinical study to evaluate the risk of cancer spread to sentinel lymph nodes in patients with early-stage melanoma. Over a period of 6 years, 146 patients were diagnosed with melanoma that had not spread more than 1.0 mm. All patients underwent sentinel lymph node testing and 6 patients were found to have cancer cells in their sentinel lymph node. These 6 patients had their local lymph nodes removed and tested in a laboratory, which confirmed the presence of cancer cells. Researchers also evaluated several biologic and patient characteristics in these patients and could not find any associations between any of these variables and the risk of cancer spread to sentinel lymph nodes.
The researchers concluded that even thin, early-stage melanomas have a risk of cancer spread to sentinel lymph nodes. They also suggested that further research is needed into determining specific variables that are associated with a higher risk of cancer spread to lymph nodes in early melanomas. Patients with thin, early-stage melanomas may wish to speak with their physician about their individual risks of cancer spread to local lymph nodes, as well as individual risks and benefits of sentinel lymph node testing.
**Reference:**Stitzenberg K, Groben P, Stern S, et al. Indications for Lymphatic Mapping and Sentinel Lymphadenectomy in Patients with Thin Melanoma (Breslow Thickness ≤1.0 mm). Annals of Surgical Oncology. 2004; 11:900-906.