Patterns of invasion and routes of tumor entry into the mandible by oral squamous cell carcinoma

Background.An understanding of the patterns, spread, and routes of tumor invasion of the mandible is essential in deciding the appropriate level and extent of mandibular resection in oral squamous cell carcinoma. Methods. A prospective study of histologic patterns of tumor invasion and routes of tumor entry into the mandible was performed in a consecutive series of 100 previously untreated patients. Results. The pattern of tumor invasion of the mandible depended on the depth of invasion both in the hard (p =.001) and soft tissues (p =.001). There was evidence that the pattern of invasion was related to histologic prognostic indicators of the disease, such as extracapsular spread from invaded lymph nodes (p =.03). The route of tumor entry was at the point of abutment to the mandible (direct) in all 13 cases, invading the dentate part of the mandible. Fifty-five percent (23 of 42) of tumors invading the edentulous ridge entered through the occlusal (superior) surface. Direct entry to the mandible in the edentulous ridge was more likely for tumors arising in the tongue, floor of the mouth and the buccal mucosa compared with alveolar or retromolar sites (p =.003). Conclusions. Larger or more deeply invading tumors in the soft tissue are more likely to invade the mandible and show the more aggressive (invasive) form of tumor spread, reducing the options of a more conservative (rim) resection. Tumors tend to enter the mandible at the point of abutment, which in both the dentate and edentulous jaw is often at the junction of the reflected and attached mucosa. A point of tumor entry below the occlusal ridge or gingival crest should be assumed when planning rim or marginal resections of the mandible. (C) 2002 Wiley Periodicals, Inc.