Prospective Clinical Study to Identify Secondary Sentinel Lymph Nodes in Patients With N1/N2b Oral Cavity or H&N Skin Cancers Using Patent Blue V and Indocyanine Green Dyes

Head and neck (H\&N) cancer has a poor prognosis and high morbidity with \~50% survival and frequent treatment resistance. Most deaths result from local or loco-regional progression rather than distant metastasis. Lymphatic spread to regional lymph nodes (RLNs), especially with extra-nodal extension (ENE), is a key predictor of poor outcomes. Current imaging techniques often miss micrometastases, leading to extensive but sometimes unnecessary neck treatments. Sentinel lymph node biopsy (SLNB) offers a precise method to detect early spread but is not yet widely adopted. Identifying second-echelon sentinel nodes-those receiving drainage from primary or first-tier nodes-may further refine treatment. The preReDSeL study evaluates the use of dyes (indocyanine green and Patent Blue V) for detecting these nodes. Success could reduce morbidity and guide tailored surgical/radiation therapy. The follow-up ReDSeL study will assess the clinical value of these findings.