RADIOIMMUNOIMAGING OF HEAD AND NECK-CANCER

Background: Squamous cell carcinoma of the head and neck frequently sp reads to regional lymph nodes in early stages. While radioimmunoimagin g has progressed to a rather routine diagnostic procedure in melanoma and colorectal carcinoma, nuclear medicine imaging in head and neck ca ncer previously was confined to nonspecific agents or cross-reacting m onoclonal antibodies primarily raised against other tumor entities. Ho wever, the ideal radioimmunoagent is directed against tumor-associated epitopes of the cancer in question and is labeled with a radionuclide combining high image quality with low radiation burden to the patient . Patients and Methods: Five patients with primary pharyngeal carcinom a metastatic to ipsilateral and in two patients also to contralateral lymph nodes were investigated using a new technetium-99m-labeled monoc lonal antibody (MoAb 174, TruScint SQ(TM)) directed against cytoskelet al proteins of squamous cell carcinoma. All patients had their tumors surgically resected, and a final diagnosis was established. Patients a lso were monitored for toxicity, induction of anti-mouse antibodies (H AMA), and serum concentrations of different tumor markers. Results: No toxicity was observed. Primary tumors were correctly identified in 5/ 5, ipsilateral jugular lymph node metastases in 4/5, and deeper cervic al metastases in 1/1 patients. Image interpretation was complicated be cause of nonspecific radioactivity in the nasal mucosa and in major ve ssels. False-positive results were found in contralateral jugular lymp h nodes, the maxillary sinus mucosa and in one glenohumeral joint. HAM A concentrations did not rise in any patient, while the concentrations of the tumor markers SCC and CYFRA-21-1 were not significantly differ ent after surgery. Conclusions: In our opinion, radioimmunoimaging by means of technetium-99m-labeled anti-squamous carcinoma antibodies rep resents a major progress in functional diagnostic oncology. It aims at the evaluation of tumor metabolism, tissue vitality, and cellular ant igenic patterns, in contrast to former less specific (and partly assoc iated with a higher radiation burden) nuclear medicine imaging modalit ies, which are based on size criteria such as clinical examination, ma gnetic resonance imaging and other morphological investigations.