(A652) Use of 111In for Sentinel Lymph Node Mapping in Patients with HNSCC

Introduction: Sentinel lymph node (SLN) mapping in patients with head and neck squamous cell carcinoma (HNSCC) has been limited by preoperative injections into oral cavity, oropharynx and laryngeal subsites in the awake patient. We hypothesize that intravenous administration of radiolabeled (111In) anti-EGFR antibody (panitumumab) goes to the primary tumor first and then drains into upper echelon LNs which will identify the SLN in HNSCC patients

Methods: We assessed 13 patients with oral cavity or oropharynx cancers who received an infusion of 111In-panitumumab several days before primary tumor resection with SLN identification and neck dissection. We measured gamma counts on LNs in situ and ex vivo. The lymph nodes were removed as standard of care with preservation of orientation in the neck (level I, II, III, IV). The three LNs with the highest gamma counts were considered the SLN and then sent to pathology for evaluation.

Results: Out of the 13 patients, 4 patients had wide separation of the SLN with other harvested nodes – suggesting a successful identification of SLN in 31%%. There were 5 (38%) metastatic LNs of which 4 were identified as SLNs. In the four patients whose metastatic LNs had higher gamma counts than their benign LNs, the average gamma count difference between metastatic and benign LNs was 116 (range: 3 – 284). In one patient the positive LN had gamma counts outside of the top three LNs.

Conclusions: With additional refinement of imaging timing, our data suggests that systemic administration of 111In-panitumamb may work as a diagnostic agent for identifying metastatic lymph nodes.