Use of computed tomography in the assessment of mandibular invasion in carcinoma of the retromolar trigone

Carcinomas originating in the retromolar trigone (RMT) are uncommon and cha racterized by early spread. Determination of mandibular invasion is signifi cant for planning therapy and determining prognosis. For oral cavity cancer s in general, CT is reasonably accurate in assessing bone invasion. However , there is a paucity of information specifically addressing the value of CT in the RMT. In this study, the records of patients with biopsy-proven RMT carcinomas treated between 1984 and 1998 were reviewed with attention to pr eoperative CT scans and histopathologic findings during surgery. Half of th e patients who were treated with primary resection had mandibular invasion. Bone invasion was not identified radiographically in 27% of patients with preoperative CT scans. The sensitivity of CT for bone involvement in RMT ca ncers was 50%, with a negative predictive value of 61.1%. The positive pred ictive value was 91.1%. These findings suggest that CT is a useful, but pot entially inaccurate, predictor of bone invasion in the RMT.