Predicting Regional Lymph Node Recurrence in the Modern Age of Tumor-Positive Sentinel Node Melanoma: The Role of the First Postoperative Ultrasound.

BACKGROUND: The Multicenter Selective Lymphadenectomy Trial II (MSLT-II) led to a change in the management of tumor-positive sentinel lymph nodes (SLNs) from completion node dissection (CLND) to nodal observation. This study aimed to evaluate prognostic factors for predicting sentinel node basin recurrence (SNBR) using data from MSLT-II trial participants. METHODS: In MSLT-II, 1076 patients were treated with observation. Patients were included in the current study if they had undergone a post-sentinel node basin ultrasound (PSNB-US) within 4 months after surgery. The study excluded patients with positive SLN by reverse transcription-polymerase chain reaction (RT-PCR) or incomplete SLN pathologic data. Primary tumor, patient, PSNB-US, and SLN characteristics were evaluated. Multivariable regression analyses were performed to determine independent prognostic factors associated with SNBR. RESULTS: The study enrolled 737 patients: 193 (26.2%) patients with SNBR and 73 (9.9%) patients with first abnormal US. The patients with an abnormal first US were more likely to experience SNBR (23.8 vs. 5.0%). In the multivariable analyses, increased risk of SNBR was associated with male gender (adjusted hazard ratio [aHR], 1.38; 95% confidence interval [CI], 1.00-1.9; p = 0.049), increasing Breslow thickness (aHR, 1.10; 95% CI, 1.01-1.2; p = 0.038), presence of ulceration (aHR, 1.93; 95% CI, 1.42-2.6; p \u3c 0.001), sentinel node tumor burden greater than 1 mm (aHR, 1.91; 95% CI, 1.10-3.3; p = 0.022), lymphovascular invasion (aHR, 1.53; 95% CI, 1.00-2.3; p = 0.048), and presence of abnormal PSNB-US (aHR, 4.29; 95% CI, 3.02-6.1; p \u3c 0.001). CONCLUSIONS: The first postoperative US together with clinical and pathologic factors may play an important role in predicting SNBR