The influence of sentinel lymph node biopsy on survival for intermediate-thickness melanoma

The Multicenter Selective Lymphadenectomy Trial-1 (MSLT-1) failed to demonstrate a survival advantage for sentinel lymph node biopsy (SNB) in melanoma. This may have been secondary to inadequate statistical power. This study was designed to determine the impact of SNB on melanoma-specific survival (MSS) in a larger patient cohort.

From 2003-2008, patients with tumors 1-4 mm in thickness and clinically negative nodes were identified within the SEER registry. Propensity score was used to create two matched cohorts: those who underwent a wide excision with SNB or wide excision alone.

A total of 15,274 met inclusion criteria and 7,910 comprised the match cohort. Average age was 67.4 years. The majority were male (62.3 %) and white (97.2 %). Primary tumors were most frequently nonulcerated (77.1 %), located on the extremity (42.3 %), and T2 (64.1 %). There were 3,955 patients in both the SNB and observation groups. There was no significant difference in gender, ethnicity, ulceration status, primary site, or T-classification between the groups. Improved 5-year MSS was associated with SNB (85.7 vs. 84.0 %), female gender (88.3 vs. 82.7 %), absence of ulceration (87.5 vs. 75.7 %), extremity location (87.4 %), T2 disease (88.6 vs. 77.9 %), and a negative SNB (88.9 vs. 64.8 %). The relationships between observation [hazard ratio (HR) 1.18], male gender (HR 1.33), ulceration (HR 1.77), head-and-neck location (HR 1.34), and T3 disease (HR 1.82) persisted on multivariate analysis.

Status of the sentinel node is the strongest predictor of survival in patients with intermediate thickness melanoma. SNB compared with observation was associated with a modest survival advantage.