Evaluation of bone scan by scintigraphy to detect subclinical invasion of the mandible by squamous cell carcinoma of the oral cavity.

A prospective study using scintigraphy was performed to compare the sensitivity of the Panorex roentgenogram and the bone scan in detecting subclinical invasion of the mandible by squamous cell carcinoma of the oral cavity and floor of the mouth. Twenty-five patients with squamous cell carcinoma of the floor of the mouth were evaluated preoperatively by both the Panorex and scintigraphic techniques and the results compared with postoperative pathologic findings. In 13 (52%) of the cases, Panorex and scintigraphic techniques were comparable in detecting tumor involvement in bone. In eight cases (32%) all three modalities had normal pathologic indications of the mandible. However, in four cases (16%) results of the scintigraphic techniques were abnormal and the Panorex, normal. In four separate cases, the extent of lesion demonstrable by scintiscanning was greater than delineated by Panorex; surgical specimen confirmed this finding. Pathologic examination of operative specimens confirmed tumor involvement. These data lead us to believe that the scintigraphic techniques may be more sensitive in detecting early mandibular involvement with squamous cell carcinoma than the Panorex technique and may help alter the therapeutic approach.