[MUSIC] In this module, I'd like to talk a little bit about malignant and pre-malignant oral disease. More specifically, I'd like to talk about leukoplakia, which is a white lesion in the mouth. Erythroplakia, which is a red velvety lesion in the mouth. And oral squamous-cell carcinoma, which is an oral cancer. Oral leukoplakia is defined as a predominantly white lesion of the oral mucosa that can not be characterized by any other definable lesion. The risk of malignant transformation of a leukoplakia is approximately 5 to 17%. Interestingly, there's a higher risk for those non-smokers, which seems somewhat counterintuitive. Well, as it turns out, patients who smoke, a normal response of the tissue is to become white and perhaps even thickened. So those that do not smoke do not have any good reason to have this white or thickened tissue. So therefore, there is a higher risk for malignant transformation in those patients that do not smoke. Additionally, if the tissue itself has a verrucal appearance, which I will describe and show a slide of in a moment, they have a higher risk of malignant transformation. Those patients that have a mixed color, both red and white, are at higher risk of malignant transformation. It turns out that there really does not appear to be a time-related progression. Erythroplakia has actually a greater risk of being dysplastic. Erythroplakia is the red velvety patch. A study of asymptomatic oral cancers revealed that 60% were mixed red and white lesions, where 35% were purely erythroplakic and 5% were leukoplakic. The risk of malignant transformation of an erythroplakic lesion upon identification is upwards of 28%. Here's a slide of an erythroplakic lesion on the alveolar mucosa in the lower jaw. As you can tell by the patient's dentition, this patient did not follow with the dentist regularly and also used significant tobacco products. Upon biopsy of this lesion, this was, in fact, an oral cancer, which leads us to a discussion of oral cancer and oropharyngeal cancer. Turns out 40,000 new cases of oral and oropharyngeal cancer are diagnosed yearly. Approximately 8,000 deaths are attributed to oral cancer on a yearly basis as well. Presently the most important factor in survival is the stage of disease at diagnosis. It turns out that localized tumors of the oral cavity and the oral pharynx have an overall survival rate somewhere of 70 to 90%. However, patients with distant metastases, stage four cancers, demonstrate an overall survival rate somewhere around 30%. Oral cancer occurring in the posterior aspect of the oral cavity and the oropharyngeal area is often associated with a worse prognosis, because these tumors are diagnosed in later stages. The only caveat to these statistics are that when cancers are caused by HPV, they tend to have a better prognosis. The risk factors for oral cancer include some very strong risk factors, and that being the use of alcohol and tobacco, particularly when they are combined. Other very strong risk factors include the use of betel nut or quid or paan that's used in certain parts of the world. Being immunocompromised also puts you at a very strong risk for oral cancer, as does having a history of a prior oral cancer. Additional strong risk factors that have been more recently identified is having a human papilloma virus infection, especially subtype 16. Let's take a look at some presentations of oral cancer. Here's a gentleman who presented to me with a lip cancer. This area was biopsied and determined to be an oral cancer. Here's a patient with an oral cancer on the dorsum of the tongue, not a usual site for an oral cancer, as it's more frequently found in the lateral border of the tongue. Here's a rather large, extensive oral cancer involving a significant portion of the lower jaw. And here's a tonsillar cancer, a cancer in this case that was HPV positive, we believe caused by the human papilloma virus subtype 16. Presently the gold standard for predicting the malignant potential of premalignant or potentially malignant lesions is the presence or degree of dysplasia. That is a histological diagnosis in showing cellular changes throughout the layers of the epithelium. However, there are some who are questioning the validity of this being as the gold standard. In fact, many scientists who study oral cancer, are now describing and defining newer molecular techniques which may predict the molecularly high risk factor or individual in an otherwise clinically normal or histologically benign tissue. As we move forward in medicine and understand these newer molecular techniques, these series of discoveries may lead to earlier identification and therefore improved patient survival statistics.
