Management and Prognostic Implications of Posteriorly Advanced OSCC in Contact With the Medial Pterygoid Muscle

T4b was previously defined as unresectable; however, it has been demonstrated that compartmental surgery can achieve treatment outcomes comparable to those of T4a cases. We frequently encounter posteriorly advanced oral squamous cell carcinoma (OSCC) in contact with the medial pterygoid muscle, and determining the appropriate extent of resection and managing subsequent recurrence in the masticator space remain challenging. Therefore, this study aimed to investigate the association between the tumor's spatial relationship with the medial pterygoid muscle and patient outcomes, providing insights to enhance diagnostic precision and guide therapeutic strategies.

This retrospective study included 50 patients with posteriorly advanced OSCC, excluding those classified as T4b. Preoperative magnetic resonance imaging classified lesions as either non-contact or contact type based on their relationship to the medial pterygoid muscle. Clinicopathological factors, overall survival rate (OS), and recurrence rates in the masticator space were compared between the two groups.

No significant differences were observed in OS between the non-contact and contacttypes. Among non-contact types, no recurrence in the masticator space was observed, whereas contact-type tumors showed a recurrence rate of 22.6% (p = 0.04). Multivariate analysis revealed that lymphatic invasion was associated with an increased risk of primary recurrence, whereas postoperative radiotherapy was associated with a reduced risk among 31 patients with contact-type tumors.

In summary, compartmental surgery with pterygomandibular space dissection should be considered for contact-type tumors near the medial pterygoid muscle, along with T4b cases. However, its indication must be assessed based on clinical findings. Postoperative radiotherapy is key to recurrence prevention, improving oncologic outcomes and long-term disease control.