The document discusses epidemiology and etiology of oral cancer. It notes that oral cancer prevalence is high in South and Southeast Asia due to cultural habits like betel quid chewing and smoking. Tobacco and alcohol are major risk factors. Nutritional factors like low fruit/vegetable intake are also associated with increased risk. The document also discusses various pre-cancerous lesions and conditions like leukoplakia, erythroplakia, and submucous fibrosis. It outlines various carcinogenic agents including viruses, nitrosamines in tobacco/cured meats, and free radicals; and how antioxidants can help prevent cancer development.

1. Iraqi Dental Students Association
I.D.S.A

2. Epidemiology and Etiology

3. Epidemiology
and Etiology
• Oral and oropharyngeal cancer of the oral cavity and pharynx
affects 10.8 of every 100.000 individuals in the United States, based
on the National Cancer Institute data.
• In South and Southeast Asia, the prevalence of oral cancer is high.
• Oral Cancer is ranked one of the sixth most frequent
malignancies in Asia.

4. Epidemiology and Etiology
• Cultural habits, including
betel quid chewing,
alcohol consumption,
and reverse smoking, as
well as low
socioeconomic status
and low consumption of
fruits and vegetables
contribute to this high
prevalence.
•

5. Epidemiology and Etiology
• The majority of oral cancers are squamous cell cancers.
• Other malignant diseases that can occur in the oral cavity
include tumors of the salivary glands, lymph nodes, bone,
and soft tissue.
• Approximately 95% of oral cancer occurs in people older
than 40 years, with average age at diagnosis of
approximately 60 years.

6. Epidemiology and Etiology
• The majority of oral cancers involve the
lateral borders and base of the tongue.
• The lips, gingiva, dorsal tongue, palate, and
salivary glands are less common sites.
• Primary squamous cell carcinoma (SCC) of
bone is rare; however, a tumor may develop
from epithelial rests and from epithelium of
odontogenic lesions, including cysts and
benign lesions.

7. Epidemiology and Etiology
• Oral cancer is age related disease, which may reflect time for
the accumulation of genetic changes and duration of exposure
to initiators and promoters.
• These include chemical and physical irritants, viruses, and
hormonal effects, In addition, decreased immunologic
surveillance over time.
• Tobacco products and alcohol are the risk factors for oral
cancer.

8. Epidemiology and Etiology
• Nicotine is a powerful and addicting drug.
• Epidemiologic studies have reported that up to 80% of oral
cancer patients were smokers.
• In addition to the risk of developing primary cancers, the risk
of recurrent and second primary oral cancers is related to
continuing smoking after cancer treatment.

9. Epidemiology and Etiology
• Alcohol, including wine, and beer, have been implicated in the
etiology of oral cancer.
• The combined effect of tobacco and alcohol result in a
synergistic effect on the development of oral cancer which
may include dehydrating effect of alcohol on the mucosa,
increasing mucosal permeability, and the effects of potential
carcinogens in alcohol or tobacco as well as influence on
central nervous system activity.
• In addition betel (Areca) Nut, Human Papilloma Virus and
nutritional factors are predisposing or precipitating factors.

11. Epidemiology and Etiology
• Nutritional factors such as
consumption of fruits and vegetables
which is associated with reduced risk
for oral cancer.
• This may be due to the antioxidant
vitamins C and E and flavonoids.
Vitamin A may play a productive role
in oral cancer.

12. Nutrition and oral cancer

13. Nutrition and oral cancer
• Oral cancer is largely a preventable disease, dietary factor
seems to be important in the prevention of oral cancer, this
has been shown in hundred of recent studies.
• Significant trend of increase risk with more frequent intake
of meat and processed meat while significant inverse trend in
risk were observed with more frequent intake of fruits and
vegetables.

14. Carcinogenic agents

15. Carcinogenic agents may be of two
types:
• Exogenous agents
• Endogenous

16. Carcinogenic agents :Exogenous agents
• Physical: ultraviolet rays, Xray and gamma rays.
• Biological: viruses.

17. Carcinogenic agents :Exogenous agents
• Chemical: e.g. nitrosamines, which a class of
carcinogenic amine that are form from nitrate and
nitrites in food, either during drying and cooking or
when the food is in the gastrointestinal tract, also found
in cigarette smoke.
• This nitrosamine is known carcinogens that may be
responsible for some cancer.
• Nitrites are also used as food additives to preserve the
color of meat, inhibit oxidation, and discourage the
growth of microorganism in meat.

18. Carcinogenic agents :Endogenous agents
• normal products of oxidative
metabolism that can cause damage to
DNA and convert normal cells to
cancer cell.
• Oxygen is essential for sustaining life,
but it could be harmful. Oxygen itself is
not the problem, but once it transform
into a free radical, it assume a
destructive power.
• Free radicals are unstable form of
oxygen they have lost an electron from
their molecular structure, (normally
these electron exist in pairs).

19. Carcinogenic agents :Endogenous agents
• To replace the lost electron free radicals actively seek out electron from
other substances in the body.
• When these materials give up an electron to the free radicals their
structure, become damaged.
• Damage to these structure can trigger the development of cancer.

20. Carcinogenic agents :Endogenous agents
• Fortunately, the bodies are
armed with antioxidants, these
substances can neutralize free
radicals, and include:
• Vitamins: vitamin C, E,
carotenoids, beta-
carotene(provitamin A)
• Minerals: selenium, manganese,
and zinc.

21. Carcinogenic agents :Endogenous agents
• Other way antioxidants may protect against
cancer by preventing chemicals from being
transformed into cancer-causing substances
or carcinogens in the first place.
• For example, vitamin C can stop the
transformation of nitrates- into powerful
carcinogens called nitrosamines but nitrates
discourage the growth of microorganisms in
meats and therefore perform an important
function
• so instead of eliminating nitrates they
added vitamin C to these foods to prevent
their transformation into carcinogenic
nitrosamine.

22. Carcinogenic agents :Endogenous agents
• It has been found from
epidemiological studies that
protection against cancer was found
among individuals who ate relatively
large amount of fresh fruits and
vegetables rich in vitamin C.
• It appears best increase intake of
vitamins from food source rather
than from large doses of vitamin
tablets because benefit can be
derived from cellulose, and from
other vitamins, minerals naturally
present in the food.

23. Inhibition of tumor
promotion and progression

24. Inhibition of tumor promotion and
progression
• Certain antioxidants such as selenium,
ascorbic acids and some poly-phenolic
compound found in green tea, fruits
and vegetables have been shown to be
effective in inhibition of tumor
promotion.

25. Vitamin A
• Large number of retinoid are
inhibitors of substances specific to
tumor promotion (in the early
stage of vitamin A deficiency,
change that resemble the early
stages of cancer occur in cells).

26. Vitamin A
• The retinoid are powerful antioxidants, protecting cellular
lipids from oxidation.
• In addition, vitamin A direct cells to produce new cells that
are identical reproduction of the original, restore normal cell
and differentiation (tumor form when new cell that are
different from the original call, begin to reproduce) so they
have been used in treatment of cancer, with some success.

27. Vitamin A
• Vitamin A also boosts immune
function, enhances cell mediated
immunity and induce a
mononuclear infiltrate in the tumor
suggesting that immune modulation
may be a protective mechanism
against the tumor.
• Retinoids are a chemoprevention
agents for oral pre-malignant
lesions, they have significant effect
but wide spread use is limited by
significant clinical toxicity.

28. Soybeans
• Interest in use of soy beans
products as a cancer
preventive agent.
• epidemiological studies
demonstrated low incidence
rate of several cancers in
population with high soy
intake.
• In Japan, which has a high
dietary intake of soy product,
the incidence rate of several
cancers is very low.

33. Leukoplakia
pre cancer leasions and conditions

34. Erythroplakia
pre cancer leasions and conditions

35. Speckled Leukoplakia
pre cancer leasions and conditions

36. Candidal Leukoplakia
pre cancer leasions and conditions

37. Oral Submucous Fibrosis
pre cancer leasions and conditions

38. Sideropenic Dysphagia
pre cancer leasions and conditions

39. Squamous Cell Carcinoma
pre cancer leasions and conditions

40. Osteoradionecrosis
pre cancer leasions and conditions