A study of the association between the prognosis of carcinoma of the mandibular gingiva and the pattern of bone destruction on computed tomography

Objective: To clarify whether the pattern of bone destruction seen on CT is more closely associated with the outcome of carcinoma of the mandibular gi ngiva than that derived from panoramic radiographs (PR). Method: Axial bone window CT scans and PR of 62 patients with carcinoma of the mandibular gingiva were evaluated retrospectively by two oral radiologi sts for the pattern of bone destruction. Patterns were classified into the three types: erosive, invasive and mixed. The relationship between these pa tterns with each imaging modality and cumulative recurrence rate, cumulativ e metastasis rate and cumulative survival rate, calculated by the Kaplan-Me ier method, were statistically analysed by the log rank test. Results: The pattern of bone destruction derived from CT was closely associ ated with the cumulative metastasis rate (P<0.05), the cumulative recurrenc e rate and the cumulative survival rate. In contrast, the pattern of bone d estruction based on the PR was not associated with the cumulative metastasi s rate (P = 0.43), the cumulative recurrence rate (P = 0.44), or the cumula tive survival rate (P = 0.5). Conclusion: The prognosis of patients with carcinoma of the mandibular ging iva is more closely related to a classification derived from the pattern of bone destruction on CT rather than PR. However, the number of subjects inv estigated in this study was nor large enough to confirm our conclusions sta tistically. Further studies by other investigators are therefore needed.