Role of proteases, cytokines, and growth factors in bone invasion by oral squamous cell carcinoma

Cancer of the lip and oral cavity is a rising problem worldwide with around 300,000 new cases per annum [1]. Squamous cell carcinoma (SCC) is detected in most patients with oral cancer [2]. Oral squamous cell carcinoma (OSCC) often happens at the gingiva and tongue and contributes above 90% of all oral cancers [3,4]. Genetic aspects and environmental factors, including alcohol abuse, smoking, viral infection, and chronic inflammation, have been associated with the pathogenesis of OSCC [5,6]. Due to the close anatomical structure of the oral mucosa and jaws, OSCC cells may frequently invade bone tissues. Tumors derived from the floor of the mouth, the retromolar zone, and the tongue invade the mandible in 62%, 48%, and 42%, respectively [7]. The patients with oral cancer generally have severe dysfunctions of speaking, chewing, and/or swallowing. Treatment and rehabilitation are particularly difficult in the patients with bone invasion. Thus, early detection and accurate prediction of bone invasion is important to plan surgical ablation and minimize the spread of tumor cells, especially to induce maxillary or mandibular conservative surgery. In general, OSCC bone invasion shows histologically two distinct patterns. One is the less aggressive erosive pattern with a tumor mass that invades on a broad pushing front and is detached from the bone by the connective tissue layer. The other is the invasive pattern in which the connective tissue layer is destroyed and the islands of tumor penetrate the bone [7-9] (Fig. 1). The formation of two patterns is affected by regional anatomic aspects of exposed bone, particularly whether the progressing front of the neoplasm contacts cancellous bone, by Int J Oral Biol 44:37-42, 2019 pISSN: 1226-7155 • eISSN: 2287-6618 https://doi.org/10.11620/IJOB.2019.44.2.37