Vital dye lymphatic mapping may stand alone

July 1, 2005

Consistent with previous reports, GPD offered a higher sentinel node identification rate overall than PBD, 97 percent vs. 93 percent, respectively.

Research study The trial included 192 patients with localized cutaneous melanoma of Breslow thickness 0.76 mm who underwent sentinel node biopsy using preoperative lymphoscintigraphy with technetium (Tc99) colloid to characterize the drainage lymphatic basin and enable skin localization of the sentinel node plus intraoperative lymphatic mapping with 1) PBD intradermal injection according to the technique of Morton et al. and 2) gamma probe detection (GPD).

Procedure particulars All of the procedures were performed at the Oncology Prevention Center, Federal University of São Paulo, Brazil, and involved the cooperative efforts of a multidisciplinary team. Renato Santos de Oliveira Filho, M.D., an oncologic surgeon, was the lead investigator. The team also included Dr. Tovo, a dermatologist in private practice, and also a researcher in the department of dermatology at the University of São Paulo Brazil, along with a nuclear medicine physician and a pathologist.

Research results Consistent with previous reports, GPD offered a higher sentinel node identification rate overall than PBD, 97 percent vs. 93 percent, respectively.

In addition, the detection rate was higher for GPD than for PBD in the axillary (95 percent vs. 84 percent) and cervical (93 percent vs. 91 percent) basins, although the two methods were complementary to each other for those sites. However, both GPD and PBD detected 100 percent of the 148 nodes excised from inguinal basins.

"The combined use of GPD and PBD for optimal identification of sentinel nodes has been advocated," Dr. Tovo says. "However, GPD requires use of expensive equipment that is available at only a limited number of centers. Further investigations are needed to confirm our results and we must also consider that there is a learning curve for performing the PBD technique. However, our study suggests that if the surgeon is skilled, then inguinal sentinel lymph node biopsy could be done using PBD alone without compromising sentinel node detection rate and with benefits for reduced cost and more widespread accessibility."

Patients represented The patients included in the study represented 103 men and 89 women who ranged in age from 18 to 81 years (mean, 44). Their primary tumors ranged in thickness from 0.76 mm to 7.0 mm (mean, 2.1) and were located on the head and neck (n = 36), trunk (n = 83) and extremities (n =73). The preoperative lymphoscintigraphy identified a total of 218 basins, including one in the mediastinum and four in the retroperitoneum that were not explored.

Study findings Histopathological examination of the excised sentinel nodes for micrometastases was performed using paraffin hematoxylin-eosin sectioning and immunohistochemical staining with S-100 protein and HMB-45 antigen. Forty six (13.4 percent) of the excised sentinel nodes were positive for tumor. Identification of micrometastasis was made using immunohistochemistry only in nine (19.6 percent) cases.

"Interestingly, the percentage of patients in this study found to have a positive sentinel node is similar to the rate reported elsewhere for patients found to have nodal metastasis after undergoing diagnostic lymph node dissection. Sentinel node biopsy offers a less aggressive alternative to detect micrometastasis and spares patients with no evidence of nodal spread from the morbidity and potential complications of elective lymph node dissection," Dr. Tovo says.

In this study, sentinel lymph node biopsy was associated with only six complications. They included cases of wound infection, hematoma and seroma and all were easily managed.