Microscopic Melanoma Metastases in Less Radioactive Sentinel Lymph Nodes Pose Risk of Progression and Mortality
In a study reported in JAMA Surgery, Luo et al found that microscopic melanoma metastases in sentinel lymph nodes that were not the most radioactive (“hottest”) were still associated with an increased risk of progression and mortality.
The study involved data from 475 consecutive patients with cutaneous melanoma with sentinel lymph nodes resected between January 2004 and June 2008 at Massachusetts General Hospital. The operative protocol included resection of all sentinel lymph nodes with radioactivity > 10% of the most radioactive lymph node. Mean follow-up was 59 months, and the last year of follow-up was 2012.
Progression and Survival
A total of 1,575 sentinel lymph nodes were analyzed in the 475 patients; 91 (19%) had positive sentinel lymph nodes, and 72 of them (79%) had metastases in the most radioactive sentinel lymph node. In 19 cases with tumor present but not in the most radioactive sentinel lymph node, technetium-99m counts ranged from 26% to 97% of the most radioactive node. Progression occurred in 43% of patients with sentinel node metastasis, irrespective of whether the most radioactive lymph node was positive. Among patients with negative sentinel lymph nodes, 11% had metastases outside of the sentinel lymph node basin, and 3.4% had recurrence within the basin.
Removal of only the most radioactive sentinel lymph node would have resulted in false-negative results in 19 (4%) of all patients and 19 (21%) of 91 patients with positive sentinel nodes.
Sentinel lymph node metastasis was associated with reduced progression-free and overall survival (P < .001), with no difference in prognosis according to whether metastasis was present in the most radioactive node or not. In patients with negative sentinel lymph nodes, mitogenicity of the primary tumor was associated with reduced progression-free and overall survival (P < .001).
The 8-year survival in patients with at least one positive sentinel lymph node was < 55%.
The investigators concluded: “Microscopic melanoma metastases was associated with disease progression and mortality, whether present in the hottest sentinel lymph node or not. These observations emphasize the importance of removing the less hot nodes, addressing a practice gap in the surgical approach to patients with melanoma.”
Lyn M. Duncan, MD, of Massachusetts General Hospital, is the corresponding author of the JAMA Surgery article.
This study was supported by departmental research funds from the Dermatopathology Unit of the Pathology Service of Massachusetts General Hospital. The study authors reported no potential conflicts of interest.
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