Pathology of advanced buccal mucosa cancer involving masticator space (T4b)

Buccal mucosa cancer involving masticator space is classified as very advanced local disease (T4b). The local recurrence rate is very high due to poor understanding of the extent of tumor spread in masticator space and technically difficult surgical clearance. The objective of this study is to understand the extent of tumor spread in masticator space to form basis for appropriate surgical resection.

All consecutive patients with T4b-buccal cancer underwent compartment resection, with complete anatomical removal of involved soft-tissue structures. Specimens were systematically studied to understand the extent of invasion of various structures. The findings of clinical history, imaging and pathologic evaluation were compared and the results were evaluated.

A total of 45 patients with advanced buccal cancer (T4b) were included in this study. The skin, mandible and lymph nodes were involved in 30, 24 and 17 cases respectively. The pterygoid muscles were involved in 34 cases (medial-pterygoid in 12 and both pterygoids in 22 cases) and masseter-muscle in 32 cases. Average distance for soft-tissue margins after compartment surgery was 2 cm and the margins were positive in 3 cases. The group with involvement of medial pterygoid muscle had safest margin with compartment surgery while it was also possible to achieve negative margins for group involving lateral pterygoid muscle and plates.The involvement of pterygomaxillary fissure was area of concern and margin was positive in 2 cases with one patient developing local recurrence with intracranial extension. At 21 months median follow-up (13-35 months), 38 patients were alive without disease while two developed local recurrence at the skull base.

T4b buccal cancers have significant soft-tissue involvement in the masticator space. En bloc removal of all soft-tissues in masticator space is advocated to remove tumor contained within space. The compartment surgery provides an opportunity to achieve negative margins for cancers actually contained within masticator space.It is inappropriate to club all patients with masticator space involvement in one group.