Table 6. Patterns of recurrence and treatment failure for nonmelanoma skin cancers with skull base invasion stratified by the route and extent of invasion.

Route and extent of skull base invasion	Patterns of recurrence and treatment failure			p Value
	Locoregional	Central	Metastatic
Direct invasion	6 (33%)	1 (6%)	11 (61%)	0.004
Zone II PNS	9 (60%)	1 (7%)	5 (33%)	0.004
Zone III PNS	2 (12%)	8 (47%)	7 (41%)	0.004

Abbreviation: PNS, perineural spread.