Oral cancer : part II

Squamous cell carcinoma and its histologic variants account for over 90% of all malignancies of the oral cavity. Early squamous cell carcinoma often presents as a white lesion (leukoplakia), red lesion (erythroplakia), or a combination of both (erythroleukoplakia). 1,2,3,4 However, with time, superficial ulceration of the mucosal surface may develop. As the lesion grows, it may become an exophytic mass with a fungating or papillary surface architecture. Some tumors demonstrate an endophytic growth pattern that is characterized by a depressed, ulcerated surface with a raised, rolled border. Pain is not a reliable indicator as to whether a particular lesion may be malignant and interestingly, most oral cancers will be totally asymptomatic or may be associated with only minor discomfort. The most common site for intraoral carcinoma is the tongue, which accounts for approximately 40% of all cases in the oral cavity proper. These tumors most frequently occur on the posterior lateral border and ventral surfaces of the tongue. The floor of the mouth is the second most common intraoral location. Less common sites include gingiva, buccal mucosa, and hard palate. The lateral tongue and floor of mouth combine to form a horseshoe-shaped region of oral mucosa, which is at greatest risk for cancer development. Two major factors help to explain why this region is at such a high risk. First, any carcinogen may mix with saliva, pool in the floor of the mouth, and constantly bathe these anatomic sites. Second, these regions of the mouth are covered by a thin, nonkeratinized mucosa, which provides less protection from carcinogens. 6 In addition to the oral cavity proper, squamous cell carcinomas also develop on the lip vermilion and the oropharynx. Vermillion carcinomas show a striking predilection for the lower lip, and usually occur in light-skinned individuals with a long history of solar damage. The lesion usually arises in an actinic cheilosis which is itself a premalignant condition. Actinic cheilosis is characterized by atrophy of the vermilion border which may develop dry, scaly changes. As the condition progresses, ulcerated sites may appear partially healed, only to recur at a later date. The evolving cancer slowly becomes a crusted, nontender, indurated ulcer or mass. Oropharyngeal carcinomas have a clinical appearance that is similar to cancers found in the oral cavity proper. Such tumors often arise on the lateral soft palate and tonsillar region, but also may originate from the base of the tongue. Unfortunately, such tumors are typically larger and more advanced at the time of discovery than compared to the more anteriorly located cancers of the oral cavity. Presenting symptoms often include difficulty in swallowing (dysphagia), pain during swallowing (odynophagia), and pain referred to the ear (otalgia).