3. Oral Cancer 26.3.19.ppt

Oral Cancer

Introduction • Oral cancers are defined as cancer of lips, mouth and tongue. • They rank amongst top three malignancies in our country. • Different studies indicate that about 5 to 12 % of all malignancies in India arise in relation to oral cavity. • Amongst oral cancers, more than 90% are squamous cell carcinoma.

Etio - pathogenesis • Etiology of oral SCC is multifactorial. • Factors implicated are – Use of tobacco

– Alcohol – Different ingredients of 'Paan' – Actinic radiation – HPV infection • Some other associated factors are: – Poor oral hygiene, – Iron deficiency,

– Syphilis, and – Candidiasis • Predominant causative factor varies in different parts of the world. It may also differ depending on site of origin of the tumour.

• For carcinoma of lip in fair skinned persons, excessive exposure to UV rays is implicated. To a lesser extent, smoking and repeated trauma also plays a role. • In India and Asia, use of smokeless tobacco and betel quid chewing is a major predisposing factor. • For cancer of the oropharynx, tobacco and alcohol abuse are the major culprits.

• In carcinoma of tonsil, oropharynx and base of tongue, presence of oncogenic variants of HPV (HPV -16) has been demonstrated in ~ 50% of cases. • Oral SCC is often preceded by leukoplakia. • The tumour is encountered more often in males. • Its incidence is increasing in persons younger than 40 years, who do not have any known risk factors. Cause unknown.

Role of tobacco as an etiological factor Epidemiological studies in India show that: –

Daily consumption of 40 cigarettes - risk increases five folds.

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daily consumption of 80 cigarettes - risk increases seventeen folds.

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Use of smokeless tobacco increases the risk four folds.

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Tobacco + Paan + SMF- risk increases nineteen times.

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Tobacco + Alcohol - risk increases the fifteen times.

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In our country ~ 40% individuals > 15 years of age consume tobacco in some form (1993).

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Epidemiological studies in western countries, show that heavy smoking in conjunction with alcohol abuse raises the risk to about 100 folds in females, and 38 times in males.

Molecular biology of SCC • For tobacco induced cancers – Mutations are seen in • p53, • p63 and • NOTCH 1

• For HPV induced cancers – Over expression of p16 and – Inactivation of p53 and RB pathways

Clinical and Gross Features • Oral SCC can present as a solitary ulcer, a lump, leukoplakia, erythroplakia, numbness of lips in absence of trauma or infection, trismus or cervical lymphadenopathy. • Tumor is found most commonly on ventral surface of the tongue, floor of mouth, lower lip, soft palate and gingiva. • Lesions on hard palate are found more frequently in reverse smokers. • Irrespective of the initial appearance of the lesion, all tumors progress to produce either a protruding mass (exophytic lesion) or an ulcer with rolled out edges (endophytic mass). • Oral cancers are notorious for exhibiting the phenomenon of field cancerization.

Squamous Cell Carcinoma

Squamous Cell Carcinoma

Squamous Cell Carcinoma

Squamous Cell Carcinoma

Squamous Cell Carcinoma

Squamous Cell Carcinoma

Site specific peculiarities of oral SCC • Tumors of lip vermillion are slow growing. They also metastasize late. • Lesions of floor of the mouth are the ones most likely to arise from pre-existing leukoplakia. They are also more likely to give rise to a second primary lesion. • Tumors of gingiva and alveolus can mimic benign lesions like pyogenic granuloma. • As oropharyngeal cancers are located posteriorly, they are more likely to present, initially as cervical lymphadenopathy, or in an advanced stage of the disease.

Histological Features

Squamous Epithelium – Normal Maturation

SCC – well differentiated • Initially dysplastic lesions are seen. For oral SCC, invasion may occur even without development of carcinoma in situ (cf cervical scc) • Tumours may range from well differentiated to anaplastic to sarcomatoid. • Degree for keratinization does not correlate with clinical behaviour.

SCC – Moderately Differentiated

SCC – Poorly Differentiated

Prognosis

• In oral SCC, stage of the tumor is more important than grade for determining the prognosis. • Metastasis occurs initially to ipsilateral lymph nodes followed by contalateral or distant lymph node involvement. Lung, liver and bones are the most frequently involved sites for blood borne metastasis. • Stage of the disease and the site of the primary tumor, are the best indicators of prognosis – Cancer of tongue • If localized: five year survival is 50%

• Stage 4 tumor: five year survival is 10% – Cancer of palate and tonsillar area • If localized: five year survival is 65% • Stage 4 tumor: five year survival is 17%

• Tumors of lip has the best ,and palate the worst prognosis. • Presence of desmoplasia indicates more aggressive behavior. • Tissue eosinophilia is a favorable prognostic sign. • Over expression of P21 and amplification of 3q26.3 locus indicates poor prognosis

– Overall survival • For stage 1: five year survival is 85% • For stage 4: five year survival is 10%

Deaths from Oral Cancer

SCC Post Surgery