SLN Biopsy May Be Sufficient for Some Melanoma Patients

NEW ORLEANS—Management of some patients with melanoma of the lower extremity could potentially stop with sentinel lymph node (SLN) biopsy, according to results presented at the 68th Annual Scientific Meeting of the American Society of Plastic and Reconstructive Surgeons. The study suggests that regional micrometastases of melanoma in the lower extremity are likely confined to the sentinel lymph nodes harvested by lymphadenectomy in some patients, said Lee L.Q. Pu, MD, PhD, resident in plastic surgery, University of South Florida, Tampa.

The researchers retrospectively examined charts from their institution recorded over the last 7 years, identifying 16 patients with lower-extremity melanoma lesions who underwent subsequent inguinal complete lymph node dissection after having a positive sentinel lymph node biopsy and wide local excision of the primary lesions.

Because complete lymph node dissection is associated with high morbidity, it is important to identify procedures that offer the least amount of risk and still allow adequate management of these patients, Dr. Pu said in a postpresentation interview with ONI.

The study identified an average of 2.5 sentinel lymph nodes in each patient, of which an average 1.5 were positive for micrometastases. Upon complete lymph node dissection, only one additional positive lymph node was found in one patient. The other 15 patients had no further histologically positive lymph nodes confirmed by complete lymph node dissection. None of the study patients developed regional recurrence during the mean follow-up of 31.1 months.

The one patient in whom complete lymph node dissection identified an additional positive lymph node was a 41-year-old woman with a 7.5-mm primary lesion located on the right knee and ankle. The primary lesion was ulcerated. One of three sentinel lymph nodes was positive, with several microscopic foci. Complete lymph node dissection showed micrometastases in 1 of 12 lymph nodes removed.

“These results indicate that some of these patients may be undergoing complete lymph node dissection unnecessarily,” Dr. Pu said. The results offer further evidence that sentinel lymph node biopsy can possibly evolve from a staging tool to a therapeutic tool in some patients, he commented.

Concerns and Reservations

Some physicians at the meeting had reservations about the findings. “I would be a little bit nervous about recommending sentinel node biopsy as the sole necessary treatment,” commented audience member Jeffrey D. Wagner, MD, associate professor of plastic surgery, Indiana University, Indianapolis.

Dr. Wagner was specifically concerned about the study’s low 6% incidence of additional positive nonsentinel nodes identified by complete lymph node dissection and its emphasis on the positive result in a single thicker lesion. Other studies, he said, have demonstrated this incidence to be anywhere from 7% to 33%, and his own group currently has work in press showing a 28% to 40% incidence that was not predicted by any patient or tumor characteristic.

“This and other studies have not subjected nonsentinel nodes to the same rigorous testing as sentinel nodes,” Dr. Wagner said. A much larger series with longer clinical follow-up will be necessary to validate the concept of sentinel node biopsy as a stand-alone therapy, he said.

“This is a preliminary study in a small series,” Dr. Pu responded. He emphasized that the sentinel lymph node biopsy sensitivity and success shown in this study could indeed change with larger series of patients. The study’s main contribution, Dr. Pu believes, is that “it provides evidence to initiate further studies to identify melanoma patients in whom sentinel lymph node biopsy can adequately manage micrometastases.”