Missed Opportunities for Neoadjuvant Immunotherapy in Melanoma: Is it Time to Consider Ultrasound Staging for Newly Diagnosed Patients?

BACKGROUND: Melanoma treatment for patients with clinical adenopathy has improved outcomes with neoadjuvant immunotherapy (NAI). Some sentinel lymph node (SLN)-positive patients have larger pathologic metastases that might be identified on ultrasound (US) preoperatively. We sought to identify SLN-eligible patients with larger nodal metastases and identify characteristics to estimate patients who might have nodal metastases identified by staging US. PATIENTS AND METHODS: Patients with clinical stage IB/II melanoma who underwent a SLNB for which the pathological size of the metastases were retrospectively identified. Comparative statistics were performed for patients with macrometastases (≥ 10 mm) compared with micrometastases (< 10 mm), as well as for 0-4 mm and 4 to < 10 mm metastases. RESULTS: There were 198 patients with clinical stage IB/II melanoma who underwent SLNB for which 41 (20.7%) had a positive node, and 39 (19.7%) had metastasis size recorded. There were 6/39 (15.4%) with a macro metastasis identified, of which 5 were clinical stage II. Median body mass index (BMI) was higher in the macro metastases group versus the micro metastases group (42.0 versus 28.9, p = 0.0307). There were 11/91 (12.1%) clinical stage II patients with metastases ≥ 4 mm. CONCLUSIONS: In our patients with stage IB/II melanoma, 15.4% had a SLN metastasis ≥ 10 mm and were more likely to be obese, suggesting physical exam was less sensitive for these patients. With a 4 mm cutoff, staging US might upstage 12% of clinical stage II to pathologic stage III. We recommend consideration of staging US for all clinical stage II patients.