Bone scanning for evaluating mandibular bone extension of oral squamous cell carcinoma.

Inability to control the primary tumor in oral cancer, leading to local recurrence, results in low survival rates. The extent of bone involvement is therefore a critical factor in planning treatment. To evaluate whether uptake of 99mTc-DPC (dicarboxypropane-diphosphate) was reliable in demonstrating the extent of mandibular involvement, 13 consecutive patients with squamous cell carcinoma of the mandibular gingiva, floor of the mouth, and lower buccal sulcus were studied. Bone involvement, as judged from preoperative radiographs and bone scans, was compared with that determined through careful analysis of histologic sections of jaw specimens. The bone scan findings corresponded well with the histologic findings in 10 cases. In contrast to earlier studies, there were no false-positive findings. False-negative bone scans were seen in three cases in which there was infiltration of the upper cortex of the mandible. A negative bone scan, therefore, cannot guarantee absence of bone involvement. Nevertheless, bone scanning seems to provide valuable information for preoperative evaluation of evident tumor infiltration of bone.