Comparison of blue dye and probe-assisted intraoperative lymphatic mapping in melanoma to identify sentinel nodes in 100 lymphatic basins.

OBJECTIVE

To determine whether combining isosulfan blue dye with a radiopharmaceutical agent will increase intraoperative detection of sentinel nodes (SNs) in patients with early-stage melanoma.

PATIENTS AND DESIGN

Clinical trial with a consecutive sample. Eighty-seven patients with clinical stage I melanoma underwent preoperative lymphoscintigraphy with 1 of 3 radiopharmaceutical agents to identify the lymphatic basin and the site of the SN. All patients subsequently underwent intraoperative lymphatic mapping and selective lymph node dissection (SLND) with isosulfan blue dye and a radiopharmaceutical agent. A handheld gamma probe determined the radioactive counts over the draining lymph node basins and individual blue-stained lymph nodes before (in vivo) and after (ex vivo) their removal. An irrelevant body site was used as the denominator of a count ratio by which absolute counts were standardized for comparison. Completion lymphadenectomy was undertaken in patients whose SLND specimen had histopathologic evidence of tumor cells.

SETTING

Tertiary care cancer center.

INTERVENTION

Lymph node sampling.

MAIN OUTCOME MEASURE

Accuracy of SN detection by blue dye and radiopharmaceutical techniques.

RESULTS

Preoperative lymphoscintigraphic images identified 100 lymph node basins and 135 lymph nodes in 87 patients. All 3 radiopharmaceutical agents were equally effective in imaging the SN before surgery. During SLND, we identified and removed 136 blue-stained and radioactive (hot) SNs and 8 additional non-blue-stained hot nodes from 98 basins (98.0%). Of the 144 excised lymph nodes, 132 nodes (91.7%) from 83 basins had either an in vivo- or an ex vivo-background count ratio of 2:1 or more and 125 nodes (86.8%) from 77 basins had a count ratio of 3:1 or more. Twelve blue-stained SNs had count ratios of less than 2:1. Seventeen SNs (11.8%) from 15 basins contained metastases: 16 were identified with blue dye and probe and 1 was identified with blue dye alone. Four (1.1%) of 377 non-SNs excised during completion lymphadenectomy contained metastases. There have been no lymph node recurrences during mean follow-up of 16.3 months (range, 7-42 months).

CONCLUSIONS

The blue dye technique remains the criterion standard for SLND in melanoma. The addition of a radiopharmaceutical tracer serves as a useful adjunct to the visualization of blue-stained SNs.