Observation after a positive sentinel lymph node biopsy in patients with melanoma.

Abstract

9033 Background: The therapeutic benefit of completion lymph node dissection (CLND) in melanoma patients with a positive sentinel lymph node (SLN) remains unknown. This study describes the natural history of selected patients undergoing nodal observation (no-CLND) after a positive SLN biopsy and compares outcomes with those undergoing immediate CLND. Methods: A prospective database was used to identify melanoma patients with a positive SLN biopsy from 1994 to 2012. Patient and tumor characteristics, reasons for not undergoing CLND, patterns of initial recurrence, and melanoma-specific survival data were analyzed. Results: Of 4319 patients undergoing SLN biopsy, 505 (12%) had a positive SLN. 170 (34%) patients underwent nodal observation and 335 (66%) had an immediate CLND. Patients in the no-CLND group were older (65 vs. 56 years, p<0.001) and more likely to have lower extremity lesions (43% vs. 30%, p=0.004). There were no differences in tumor thickness, Clark level of invasion, presence of ulceration, or degree of SLN tumor between groups. In 89% of cases, the reason to forgo CLND was due to doctor and/or patient decision. Median follow up was 23.5 and 78.5 months for no-CLND and CLND groups and median time to first recurrence was similar at 9 and 12 months (p=NS) respectively. There was no difference in regional recurrence rates between groups (20%). Nodal disease as a site of first recurrence occurred in 16% of patients in the no-CLND group compared with 7% of CLND patients (p<0.001). In contrast, systemic disease as first site of recurrence occurred in 8% of no-CLND patients compared with 27% of CLND patients (p<0.001). While median relapse-free survival was better after CLND (34.5 vs. 20.9 months, p=0.02), melanoma-specific survival was similar (not reached, no-CLND vs. 110 months, CLND, p=0.14). Conclusions: Immediate CLND after a positive SLN biopsy is associated with fewer initial nodal basin recurrences but similar melanoma-specific survival. These results support ongoing equipoise in the two arms of MSLT-II.