To determine the rate and clinicopathologic factors predictive of sentinel lymph node (SLN) positivity, regional lymph node recurrence, and survival in a large series of patients with thin primary cutaneous melanoma who underwent SLN biopsy (SLNB).
Patients with thin (≤1 mm) melanomas who underwent SLNB between 1992 and 2009 at Melanoma Institute Australia were identified from the Melanoma Institute Australia database. The association of clinicopathologic features with SLN status, lymph node recurrence, and survival was analyzed.
In 432 patients [226 men, 206 women; median age 49.5 years (range: 14.4–85.0 years)], SLNB was positive for metastatic melanoma in 29 (6.7%) patients. No SLN positivity was detected in 37 patients with primary tumor thickness 0.50 mm or less. Breslow thickness (P = 0.012) and presence of lymphovascular invasion (P = 0.018) were the only factors significantly associated with SLN positivity. Regional lymph node recurrence was significantly more common in tumors located in the head/neck region (4/33, 12%) than in extremities (3/245, 1.2%) and trunk (2/154, 1.3%) (P < 0.001). Primary tumor mitotic rate was a significant predictor of melanoma-specific survival (Hazard Ratio [HR] = 1.2, 95% confidence interval: 1.09–1.35, P < 0.001).
There is a low but significant rate of SLN positivity in patients with primary melanomas 0.51 to 1.0 mm in thickness. Given its prognostic importance, SLNB should be considered in such patients, particularly if there is lymphatic permeation by melanoma at the primary tumor site. More frequent regional node field recurrences in patients with head/neck primary tumors may be a consequence of complex lymphatic drainage patterns in this region.
In this study of 432 patients with thin primary cutaneous melanomas, there was a low but significant rate of sentinel lymph node positivity in patients with primary melanomas 0.51 to 1.0 mm in thickness. Given its prognostic importance, sentinel lymph node biopsy should be considered in patients with melanomas more than 0.50 mm in thickness.
*Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
†Melanoma Institute Australia, North Sydney, New South Wales, Australia; and Disciplines of
§Surgery, Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia.
Reprints: Rajmohan Murali, MBBS, MD, FRCPA, Human Oncology and Pathogenesis Program, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, Box 20, New York, NY 10065. E-mail: MuraliR@mskcc.org.
All of the listed authors give final approval of the version to be published.
Disclosure: Professor Scolyer is a Cancer Institute New South Wales Clinical Research Fellow.