Thin vs. Thick Melanomas: Both Carry Same SLN Risk
FROM A SYMPOSIUM SPONSORED BY THE SOCIETY OF SURGICAL ONCOLOGY
Major Finding: A positive sentinel lymph node was identified in 8.2% of patients with thin melanomas and positive deep margins vs. 9% of those with thicker margins, regardless of margin status.
Data Source: Retrospective analysis of 260 patients with cutaneous melanoma.
Disclosures: The authors reported no relevant financial disclosures.
SAN ANTONIO – Patients with thin melanomas and positive deep margins on initial biopsy had the same incidence of sentinel lymph node metastasis as those with thicker melanomas, according to the results of a retrospective analysis of 260 patients with melanoma.
At least one positive sentinel lymph node was detected in 6 of 73 patients (8%) with a melanoma Breslow thickness of less than 0.8 mm and positive deep margins vs. 17 of 187 patients (9%) with a melanoma Breslow thickness of 0.8-2.0 mm, regardless of margin status (P = .82).
Immunohistochemistry was the most common method of identifying positive sentinel nodes in both the thin and thick melanoma groups (5 cases vs. 10 cases, respectively), Dr. Victor Koshenkov said at a symposium sponsored by the Society of Surgical Oncology.
The decision to perform sentinel node biopsy is largely driven by tumor thickness. When the initial biopsy of a thin melanoma shows positive deep margins, many clinicians will treat these cases as potentially thicker melanomas and perform sentinel lymph node (SLN) biopsy. There are few data on the impact of positive deep margins on surgical decision making, prognosis, and outcome, even though positive deep margins are the most common cause of incompletely measured or indeterminate tumor thickness, said Dr. Koshenkov of the department of surgery at Atlantic Health Memorial Hospital in Morristown, N.J.
He presented data from a retrospective analysis of 260 adult patients who underwent wide excision plus SLN biopsy for cutaneous melanoma from January 2004 to May 2010.
Demographics were not statistically different between the two groups, except for tumor site and Clark’s level, he said. In 53% of patients in the thicker melanoma group, the extremities were the primary tumor site vs. 38% in the thin melanoma group (P = .042), while 40% had Clark’s level IV-V vs. 22% in the thin melanoma group (P less than .001).
Multivariate regression analysis revealed that only female gender (P = .046; odds ratio, 2.68) and Clark’s level IV-V (P = .024; OR, 3.54) were significantly associated with an increased risk of positive SLNs. Belonging to the thin melanoma group versus the thicker melanoma group was not significant (P = .66; OR, 1.29) Dr. Koshenkov said.