The influence of the pattern of mandibular invasion on recurrence and survival in oral squamous cell carcinoma

Background. Controversy exists over the predictive value of the presence and pattern of tumor invasion of the mandible in oral squamous cell carcinoma (SCC). Many authors have questioned increasing the classification of small tumors to T4 on the basis of mandibular invasion alone. There are little data on the influence of the pattern of invasion on prognosis. Methods. We prospectively reviewed 100 consecutive mandibular resections for previously untreated oral SCC. Clinical and pathologic data collected included details of soft and hard tissue histologic findings. Outcomes included recurrence (local, regional, and distant metastases), disease-specific survival, and death from other causes. The median follow-up for survivors was 65 months. Results. Of 100 cases, 65 involved segmental and 35 involved marginal resections. Sixty-two percent of mandibles were invaded by tumor. Local recurrence occured in 21% and was strongly correlated with tumor size, nodal involvement, and pattern of soft tissue invasion. The 5-year disease-specific survival was 68%, and the crude survival was 50%. Mandibular invasion predicted for recurrence and disease-specific survival, even after correcting for the effects of other variables. The pattern of mandibular invasion (erosive/infiltrative) was also predicted for recurrence and disease-specific survival. Conclusions. Even in the presence of mandibular invasion, soft tissue factors are the most important determinants of prognosis. Upstaging tumors on the basis of mandibular invasion is justified. An infiltrative pattern of bone invasion is a marker of aggressive tumor biology and should be included in the pTNM classification