Abstract
To investigate the tumor extent pattern of gingival carcinoma of the mandible, 98 surgically treated patients with squamous cell carcinoma (SCC) of the lower gingiva were clinicopathologically examined. Tumor extent pattern was classified as follows: intraosseous extent type (type I), buccal extent type (type B), lingual extent type (type L), exophytic type (type E), and gingival surface extent type (type G). Each group was further divided into two subgroups: with or without invasion into surrounding tissue.
Bone invasion involving the mandibular canal was noted in types I, B, and L. Moreover, tumors with surrounding tissue invasion frequently showed diffuse bone invasion. Regarding mandibular resection, in type I, the mandibular resection level was determined based on the degree of bone invasion. In types L and B, however, segmental mandibulectomy was often selected in cases with periosteal invasion exceeding the muscular attachment level, such as mylohyoid muscle and buccinar muscle. The incidence of local recurrence was higher in types I, B, and L, compared with types E and G. In particular, 31% of type L tumors with invasion into surrounding tissue had local recurrence. Neck metastasis was also significantly increased in such cases of type L. The overall cumulative five-year survival rate was 86.7%.
Treatment for gingival cancer of the mandible is mainly focused on bone invasion; however, evaluation of the tumor extent pattern is also an important factor to determine adequate surgical resection. Thus, establishment of standards of diagnosis and treatment for lower gingival cancer are necessary.
