Background: Limited evidence stratifies patients at-risk for poor survival outcomes in buccal squamous cell carcinoma (SCC), particularly within the United States where oral cavity cancer is more common at other subsites.
Objective: The primary objective of this study was to evaluate clinical and histopathologic characteristics predictive of survival outcomes in an exclusively buccal SCC, United States-based cohort.
Methods: A retrospective analysis of all patients with archived specimens available for review who were treated for primary buccal SCC from 1/1/1992 to 12/31/2017at a large tertiary referral center was performed. Histopathologic review included all characteristics currently recommended by the recently revised, 2017 College of American Pathologists (CAP) synoptics for reporting of oral cavity cancers.
Results: Eighty patients with primary buccal SCC were identified, half whom were men, with a mean age at surgery of 67 years. The cohort included 37% T1, 35% T2, 8% T3, and 20% T4A at diagnosis (Table 1). Overall survival rates (95% CI) at 1, 3, and 5 years following surgery were 85% (77-94), 61% (49-74), and 40% (29-56), respectively. Age at surgery (hazard ratio for a 10-year increase of 1.39; 95% CI 1.09-1.76; p=0.007), perineural invasion (hazard ratio of 2.10; 95% CI 1.03-4.29; p=0.041), and single cell worst pattern of invasion (WPOI-4/5) (hazard ratio of 3.87; 95% CI 1.30-11.49; p=0.015) were significantly associated with overall survival (Table 2). Depth of invasion was not significantly associated with local recurrence, regional recurrence, distant metastases-free survival, or death from any cause (all p>0.05; Figure 1).
Conclusion: Using the recently revised CAP guidelines, the current study shows that patients demonstrating perineural invasion and single cell morphology (WPOI-4/5) exhibited a 2-fold and nearly 4-fold higher risk of death, respectively. In contrast to other, more common SCC subsites and reports from areas with endemic buccal SCC, depth of tumor invasion does not significantly predict regional recurrence or overall survival in this United States-based cohort.
Figure 1. Univariable associations of depth of invasion with (A) local recurrence, (B) regional recurrence, (C) any disease recurrence and distant metastases-free survival, and (D) death from any cause.