Role for lymphatic mapping and sentinel lymph node biopsy in patients withthick (>= 4 mm) primary melanoma

Background: Historically, patients with thick (greater than or equal to 4 m m) primary melanoma have not; been considered candidates for elective lymph node dissection, because their risk for occult distant disease is signific ant. Sentinel lymph node (SLN) biopsy offers an alternative approach to ass ess disease in the regional nodal basin, but no studies have specifically a ddressed the role for this technique in patients with thick melanoma. Altho ugh adjuvant therapy benefits patients who develop nodal metastases, data t hat supports its routine use in all patients with thick melanoma is both li mited and controversial. This study was performed to determine whether path ological status of the SLN is an important risk factor in this heterogeneou s group and, thus, provides a rationale for SLN biopsy. Methods: The records of 131 patients with primary cutaneous melanoma whose primary tumors were at least 4 mm thick and who underwent lymphatic mapping and SLN biopsy were reviewed. Several known prognostic factors, i.e., tumo r thickness, ulceration, Clark level, location, sex, as well as SLN patholo gical status were analyzed with respect to disease-free and overall surviva l. Results: Lymphatic mapping and SLN biopsy was successful in 126 (96%) of 13 1 patients who underwent the procedure. In 49 patients (39%), the SLN biops y was positive by conventional histology, although it was negative in 77 pa tients (61%). The median follow-up was 3 years. Although presence of ulcera tion and SLN status were independent prognostic factors with respect to dis ease-free and overall survival, SLN status was the most powerful predictor of overall survival by univariate and multivariate analyses. Conclusions: Lymphatic mapping and SLN biopsy is a highly accurate method o f staging lymph node basins at risk for regional metastases in patients wit h thick melanoma and identifies those patients who may benefit from earlier lymphadenectomy as well as patients with a more favorable prognosis. Patho logical status of the SLN in these patients with clinically negative nodes is the most important prognostic factor for survival and is essential to es tablish stratification criteria for future adjuvant trials in this high-ris k group.