Head and neck squamous cell carcinomas (HNSCC) are common cancers with a relatively poor prognosis. Locoregionale recurrences are regularly encountered and associated with a detrimental outcome. Studies of the last few years report that not only tumor staging and grading influence locoregional control but also histologic and biological markers. One such histological marker is coined "worst pattern of invasion". It describes a histologic growth pattern consisting of invading tumor cell islands and strands that are dispatched from the invasion front (POI typ 4 and 5). Additional features of invasion are perineural invasion and extracapsular nodal extension. Besides histological markers there are molecular characteristics that include the expression of gene families involved in extracellular matrix degradation. The data suggest that head and neck cancers differ with respect to their invasive growth capacity and thus their ability to generate locoregionale recurrences. It appears that locoregionale control is a consequence of this growth pattern. This may explain, why in recent clincial studies the prognostic marker "pattern-of-invasion" outweights even such well established prognosticators such as "surgical margins".