This document discusses the epidemiology of cancers. It notes that cancer is the second leading cause of death in the US and fourth in India. The most common cancers vary between developed and developing countries. Cancer incidence depends on predisposing factors like familial, genetic, racial, environmental, age, and sex factors as well as chronic pre-malignant conditions and hormones. Some key points are that familial cancers are more common, smoking and alcohol increase cancer risk, and hormonal factors like estrogen can increase risks of certain cancers.

1. EPIDEMIOLOGY OF
CANCERS

2. CANCER INCIDENCE:
• Cancer incidence- new cancer cases registered in given
period of time.
• 20 % of deaths in world are due to cancers.
• In INDIA- CANCERS are 4th leading cause of deaths.
(1st -heart disease)
• In USA- 2nd leading cause of deaths after heart
diseases.

3. Most common cancers in
1. Developed countries: Lung, Breast, Prostate
& Colorectal.
2. Developing countries: Liver, Cervix, Oral
Cavity & Oesophagus.

4. INCIDENCE OF CANCER DEPENDS UPON THE
FOLLOWING FACTORS:
INCIDENCE
A. PREDISPOSING
FACTORS
B. CHRONIC PRE-
MALIGNANT AND NON-
NEOPLASTIC
CONDITIONS
C. HORMONES

5. A. PREDISPOSING FACTORS
1. FAMILIALAND GENETIC FACTORS
2. RACIALAND GEOGRAPHIC FACTORS
3. ENVIRONMENTAL AND CULTURAL
FACTORS
4. AGE
5. SEX

6. 1. FAMILIAL AND GENETIC FACTORS:
• Familial predisposition and heredity play a role in the
development of cancers.
• History of cancers in family- higher chance of
cancers in off-springs & appear at early age at
multiple places.
• First degree relatives are more prone to get cancers
than secondary or tertiary degree relatives.

7. • Examples to justify above factor:
a. Cancer of breast:
• Female relatives of breast cancer patients
(1st degree) are at higher risk of developing
breast cancer due to inheritance of breast
cancer genes : BRCA1 &BRCA2 genes

8. b. Familial polyposis coli:
• APC cancer genes are inherited to offspring
and cause familial polyposis coli.
• Initially as benign tumours of colon
followed by malignant transformation.

9. 2. RACIAL AND GEOGRAPHIC FACTORS:
White Europeans and
Americans:
• Common malignancies
of the prostate, lung,
breast and colorectal
region.
• Liver cancer is
uncommon in these
races.
Japanese:
•Five times higher incidence
of carcinoma of the
stomach than the
Americans.
•Breast cancer is uncommon
in Japanese women than
American women

10. Black Africans:
• More commonly
cancers of the skin,
penis, cervix and liver.
Indians:
•Both sexes have higher
incidence of carcinoma
of the oral cavity and
upper aerodigestive tract.
•while in females
carcinoma of uterine
cervix and of the breast
run parallel in incidence.

11. 3. ENVIRONMENTAL AND CULTURAL FACTORS
I. CIGARETTE SMOKING:
(Active as well as Passive
Smoking)
• Most important etiological factor
of cancer of the lungs,
Gastrointestinal tract and organs,
kidney, urinary bladder, uterine
cervix and myeloid leukaemia.

12. II. ALCOHOL ABUSE: Predisposes to the
development of cancer of mouth, pharynx,
larynx, breast, oesophagus, intestine and liver.

13. • Synergistic interaction of alcohol and tobacco
further accentuates the risk of developing cancer of
the upper aerodigestive tract and lung.

14. III. CANCER OF THE CERVIX in women is linked
to a number of factors such as
- Early age coition,
- High frequency of coition,
- Multiple partners,
- Multiparity.

15. IV. PENILE CANCER: is rare in the Jews
and Muslims as they are customarily
circumcised.
• Carcinogenic component of smegma appears
to play a role in the etiology of penile cancer

16. V. BETEL NUT:
• Chewing of it causes oral cancer.

17. VI. INDUSTRIAL AND ENVIRONMENTAL
SUBSTANCES:
• Exposure to substances like Arsenic, Asbestos,
Benzene, Vinyl Chloride, Naphthylamine cause
various types of cancers.

18. VII. CONSTITUENTS OF DIET:
• More animal fat consumption, eating less fiber, low
Vit-A in diet predisposes to colonic cancer esp in
obese people.
• Diet rich in vitamin E protects against cancer due to
its antioxidant property.

19. 4. AGE:
• Most significant risk factor for cancer is AGE.
• Generally, cancers occur in older individuals past 5th
decade of life (two-third of all cancers occur above 65 years
of age), though there are variations in age incidence in
different forms of cancers.
• Higher incidence of cancer in advanced age could be due to
alteration in the cells of the host, longer exposure to the
effect of carcinogen, or decreased ability of the host
immune response.

20. • Some tumours have two peaks of incidence
e.g. acute leukaemias occur in children and in
older age group
Young age group old age group

21. 5. SEX:
• Most tumours are generally more common in men
than in women except cancer of the breast,
gallbladder, thyroid and hypopharynx.
• Cancer of the breast is the commonest cancer in
women throughout the world while lung cancer is
the commonest cancer in men.

22. B. CHRONIC PRE-MALIGNANT AND NON-
NEOPLASTIC CONDITIONS:
• Premalignant lesions are a group of conditions which
predispose to the subsequent development of cancer. They
are:
1. Dysplasia and carcinoma in situ.
2. Some benign tumours.
3. Miscellaneous conditions.
 Inflammatory
 Hyperplastic

23. 1. Dysplasia and carcinoma in situ.
• Dysplasia means ‘disordered cellular
development’, often preceded or accompanied
with metaplasia and hyperplasia.
Eg:
1. Cervical dysplasia.
2. Barrett’s oesophagus with dysplasia.

24. Barrett’s oesophagus with dysplasia Cervical dysplasia

25. • Most marked cytological atypia confined to epithelial layers
above the basement membrane without invading the basement
membrane is called as carcinoma in situ or intraepithelial
neoplasia (CIN)/Non-invasive cancer.
Eg:
1. Cervical Intraepithelial Neoplasia.
2. Ductal carcinoma in situ of the breast is the most common precancer in
women.
3. Bowen's disease is a squamous carcinoma in situ of the skin.
4. Actinic or solar keratosis.
5. Oral leukoplakia.

26. Actinic or solar keratosis
Oral leukoplakia

27. Bowen's disease Ductal carcinoma in situ

28. 2. Some benign tumours
• Commonly, benign tumours do not become malignant.
• However, there are some exceptions
e.g.
1. Multiple adenomas of the large intestine have high incidence of
developing Adenocarcinoma.
2. Neurofibromatosis (von Recklinghausen’s disease) may develop
into sarcoma.
3. Pleomorphic adenoma (mixed salivary tumour) may sometimes
develop carcinoma (carcinoma ex pleomophic adenoma).

29. Multiple adenomas
Neurofibromatosis
Pleomorphic adenoma of parotid gland

30. 3. Miscellaneous:
Miscellaneous
INFLAMMATORY
CONDITIONS
HYPERTROPHIC
CONDITIONS

31.  INFLAMMATORY CONDITIONS:
which become malignant.
A- CHRONIC CERVICITIS
B- ULCERATIVE COLITIS
C- H-PYROLI GASTRITIS
D- CHRONIC BRONCHITIS

32. A- CHRONIC CERVICITIS:
• HPV induced Chronic Cervicitis  High risk
of cervical cancer.

33. B- ULCERATIVE COLITIS:
• Chronic Ulcerative Colitis may become
Colon cancer in long standing cases.
• High risk.

34. C- H-PYROLI GASTRITIS:
• Gastritis may develop into Gastric cancer and
lymphoma.
Gastric cancer
Gastric lymphoma

35. D- CHRONIC BRONCHITIS
• Chronic bronchitis in heavy cigarette smokers
may develop cancer of the bronchus.

36.  HYPERPLASTIC CONDITIONS: which become
malignant.
A. CIRRHOSIS OF THE LIVER.
B. OLD BURN SCAR (MARJOLIN’S ULCER).

37. A. CIRRHOSIS OF THE LIVER
• Predisposition to develop Hepatocellular carcinoma.

38. B. OLD BURN/WOUND
SCAR (MARJOLIN’S
ULCER).
• Squamous cell carcinoma
(MARJOLIN’S ULCER)
developing in an old scar
(SCAR FORMED DUE TO BURN/WOUND/CHRONIC INFLAMMATORY CONDITIONS)

39. C. HORMONES AND CANCER:
• Cancer is more likely to develop in organs and tissues
which undergo proliferation under the influence of
excessive hormonal stimulation.
• On cessation of hormonal stimulation, such tissues
become atrophic.
• Hormone-sensitive tissues developing tumours are
the Breast, Endometrium, Myometrium, Vagina,
Thyroid, Liver, Prostate and Testis.

40. • Hormones which cause cancers when
excessive amounts are released/taken are:
1. OESTROGEN.
2. CONTRACEPTIVE HORMONES.
3. ANABOLIC STEROIDS.

41. 1. OESTROGEN:
• Women
- Receiving Oestrogen therapy &
- With oestrogen-secreting Granulosa
cell tumour of the ovary.
• Adenocarcinoma of the vagina is seen with increased
frequency in adolescent daughters of mothers who had
received oestrogen therapy during pregnancy.
have increased risk of
developing endometrial
carcinoma

42. 2. CONTRACEPTIVE HORMONES:
• Abuse of oral contraceptives (combined) increase the
risk of developing breast cancer in females.
Also liver tumours
(benign and malignant)

43. 3. ANABOLIC STEROIDS:
• Consumption of anabolic steroids by athletes to
increase the muscle mass is not only unethical athletic
practice but also increases the risk of developing
benign and malignant tumours of the liver.