Proposed sub-compartmentalization of high infratemporal fossa involvement in gingivobuccal cancers and its impact on clinical outcome and staging

Abstract

According to the American Joint Committee on Cancer (AJCC) eighth edition, involvement of the masticator space and infratemporal fossa (ITF) by oral cancer signifies advanced disease (T4b), which is most often deemed unresectable. The extent of ITF involvement impacts the management and outcomes. The extent of T4b disease needs to be subclassified for optimal management. T4b disease with infra-notch extension is associated with a favorable prognosis compared to supra-notch disease. Certain cases with supra-notch involvement may potentially be converted to resectable disease following neoadjuvant chemotherapy. We performed a comprehensive search of abstracts of ITF subdivisions and their impact on staging as per the AJCC eighth edition. We included studies reporting data on ITF subdivisions and their impact on clinical outcomes. The key words for Medical Subject Headings were “cross-sectional imaging,” “oral carcinoma,” “AJCC 8 th edition,” “infratemporal fossa,” “masticator space,” “survival,” and “neoadjuvant chemotherapy.” We selected 30 studies that had been published in English. We propose that the T4b category needs to be classified into compartments that have predictive and prognostic implications, including Compartment 1 comprising the low ITF (medial pterygoid and masseter), Compartment 2 comprising the anterior high ITF (retroantral fat), Compartment 3 comprising the posterior high ITF, Compartment 3a comprising the paramandibular compartment (temporalis), Compartment 3b comprising the lateral pterygoid, and Compartment 3c comprising the perineural compartment (pterygopalatine fossa and pterygomaxillary fissure). Our proposed subclassification of T4b will impact the patients' management and outcomes.