Association of pattern of mandibular invasion in MDCT with recurrence in oral cancers

Background: Mandibular invasion has been a long-debated criterion for predicting prognosis in oral cancers. Though the American Joint Committee on Cancer (AJCC) marks cortical erosion in oral lesions as T4 disease, it is often challenged that mere superficial bony erosion should not be used to demark T4 disease. Aim: This study aimed to evaluate the association of pattern of mandibular erosion in preoperative Multi-Detector CT (MDCT) of oral cancers with the presence of recurrent loco-regional malignant disease. Materials and Methods: A retrospective study was done in the Department of Radio-Diagnosis of a tertiary center in Western India. MDCT Neck findings in 56 consecutive postoperative patients clinically suspected for recurrent oral carcinoma over a period of 1 year were assessed. Preoperative MDCT of all patients was evaluated for presence and pattern of mandibular involvement by primary malignancy. These patterns were compared with the presence of recurrent disease in the postoperative scan. Association between two findings was tested by Fisher's exact test. Results: Forty-eight patients showed features of recurrent malignancy on MDCT confirmed by biopsy; of which 10 patients had shown no bony invasion in the preoperative scan, 14 had shown cortical erosion and 24 showed medullary invasion. P value for association of recurrence and bony invasion pattern was found to be 0.6705 (insignificant) for cortical erosive lesions and 0.0469 (significant) for medullary infiltrative lesions. Conclusion: Only medullary infiltrative lesions of the mandible have a statistically significant association with recurrent disease and may be used as a prognostic factor. Cortical erosions are statistically insignificant in predicting recurrence similar to no bone invasions.