Extent of local invasion and safe resection in cT1–2 tonsil cancer

Abstract

Although intraoral resection of small-sized tonsil cancer achieves excellent tumor control, the extent of local invasion and adequate safety margin in resection have not been studied. Thus, we aim to determine the extent of local invasion in terms of mucosal spread and deep infiltration in stage T1-2 tonsil cancer. We re-analyzed the surgical specimens from 49 cT1-2 tonsil cancers. Microscopic tumor cell extension from the tumor gross boundary of specimens was assessed in representative sections of each tumor. We also tested whether local extension correlates with human papilloma virus (HPV) status of tumors. The extent of microscopic deep invasion from the gross tumor border was 0.52 ± 0.41 mm, which was significantly less than that of mucosal spread (0.83 ± 0.61 mm, P = 0.01) in cT1-2 tonsil cancer. The microscopic deep invasion correlated with tumor size (rho = 0.703, P < 0.001). We found tumor invasion into superior constrictor muscles in 58.1%, no cases of tumor invasion into the deep fascia. In terms of HPV status (genotyping plus p16 staining), there were no differences in microscopic tumor extension. Our detailed pathologic analyses confirm that an oropharyngectomy including the superior constrictor muscle is an oncologically safe procedure for stage T1-2 tonsil cancer.