A NOVEL TC-99M LABELED MONOCLONAL-ANTIBODY (174H.64) FOR STAGING HEADAND NECK-CANCER BY IMMUNO-SPECT

A novel murine monoclonal antibody (MAb 174H.64) was labeled with Tc-9 9m by a direct method. MAb 174H.64 detects a cytokeratin-associated an tigen which is expressed by over 90% of all squamous cell, carinomas. Panendoscopy, sonography and computerized tomography scan were perform ed in all cases as well as magnetic resonance imaging (in selected pat ients). Pre-operative immunoscintigraphy was performed in 21 patients with histologically proven primary carcinomas (18 with remaining prima ry tumors and 3 with lymph node recurrences). Scintigraphic images wer e obtained 4-6 h after injection of 1.1 GBq of the Tc-99m-labeled anti body (2 mg). Late images were acquired 18 to 24 h after injection. Sin gle-Photon-Emission-Computed Tomography (SPECT) of the head and thorax was performed in all patients. The primary tumors were immunoscintigr aphically visualized in all 18 patients,vith remaining primary tumor. Fifteen of 18 loco-regional lymph node metastases were visualized by i mmunoscintigraphy (the smallest lesions had a diameter of <1 cm), in o ne patient lymph node metastases were detected by immunoscan only. Two metastatically involved lymph nodes were identified by histology only (micrometastases). Distant metastases were present in 3 patients, of which two were identified by immunobscintigraphy. Immuno-SPECT accordi ng to this method was a sensitive and specific imaging modality for pr eoperative staging of patients with squamous cell carcinoma of the hea d and neck and detected lymph node metastases with higher accuracy tha n conventional clinical and imaging modalities.