Definition, types, causative agents...etc

1. CANCER…..
DR.V.JEYANTHI KUMARI,
ASSISTANT PROFESSOR OF ZOOLOGY,
A.P.C.MAHALAXMI COLLEGE FOR WOMEN,
THOOTHUKUDI-2
TAMILNADU.

4. INTRODUCTION
Cancer is a tumour. It is an abnormal overgrowth or
enlargement of tissue.
It has no co-0rdination with the normal tissue.
Cancers now cause the second largest number of
deaths in most countries.
Definition
Cancer is an independent, autonomous,
uncontrolled growth of a tissue containing a mass
of aberrant or abnormal cells

7. PROPERTIES OF CANCER
1. It arises from an existing tissue or cells of the body.
2. The growth of the tumour is autonomous. It follows its own laws of
growth.
3. It is not regulated by those governing the tissues or cells.
4. The tumour cells are undifferentiated and anaplasdtic in nature.
Anaplasia
It refers to the reversion of differentiated cells into undifferentiated
or embryonic cells.
5. They have a greater potentiality for growth and multiplication.
6.They carry out none of the functions of normal adult cells.
7.They have large and irregular nuclei.
8.They lose their contact inhibition.

8. CONTACT INHIBITION
Normal cells stop movement and division when they make
contact with each other. This phenomenon is called contact
inhibition.
Cancer cells have no contact inhibition, it becomes
cancerous.
NUCLEUS
It is larger in size and irregular in shape.
The nucleolus is also large in size and it exhibits
hypertrophy (The enlargement of organ or tissue……..)
CHROMOSOMAL ABNORMALITY
This is due to abnormal mitosis.
The misbehaviour of centrioles is another characteristic
feature of cancer cells.

9. • Plasma membrane becomes leaky.
Growth promoting factors
1.The cancer cells release an excessive amount of
growth promoting factors.
2. They escape by leakage through the cell
membranes.
3.After, it has leaked out, it acts on the surface of the
neighbouring cells.
4. Thus inducing abnormal growth and multiplication
of the normal cells.

10. CAUSES OF CANCER
I.CHRONIC IRRITATION
• Chronic irritation causes cancers.
• Ex. Irritation caused to the tongue by broken or malformed
teeth has often led to the cancer of the tongue.
• Cancers of the lip were quite common when clay pipes
were in use.
II. ATMOSPHERIC POLLUTION
• Reports says that, people living in the city sides are eaily
prone to cancers than country sides.
• It is true that the atmosphere of the cities are polluted with
the products of the combustion of coal and oil and with
motor exhaust gases.

11. • The increase in th industrilization caused a corresponding
increase in cancer cells.
III. SMOKING
Heavy smoking of cigarettes cause and increase in the
number of lung cancer cases.
Positive evidence that cigerette smoking alone cause lung
cancer
IV.RADIATION
Excessive radiation also causes cancers(x rays, cosmic rays).
X rays without appropriate shielding and other protective
devices make patient to the direct exposure of rays and
cause cancers.

12. V.CHEMICALS
Chemical substances added to food and medicines may
have the effect of causing the development of cancers.

13. TYPES
Classified into 2 ways. They are
1.Basis of pain
2.Basis of tissues
Based on the pain, the cancers are classified into
1.Malignant tumour and 2. nnon-malignant tumour.
MALIGNANT TUMOUR
1. It gives pain, grows rapidly and spreads from the
place of its origin to other parts of the body, nearby
or away.

14. NON-MALIGNANT TUMOUR(BENIGN TUMOUR)
1.This cancer do or do not harm the possessor. It is
confined to the area in which it originated.
2.Its growth is always slow.
Cancers on the basis of the tissues they originate , classified
into 8 types. They are,
1.CARCINOMA
a. It arises from epithelial cells.
b. It occurs on the skin, in the lining membrane of internal
organs.
2.SARCOMA
a. Arising from any connective tissue and mesenchymal cells.

16. sarcoma

17. Osteoma

18. Fibroma

19. melanoma

20. Lymphoma

21. teratoma

22. 3.OSTEOMA – Tumors of bone.
4.FIBROMA – Tumour arising from fibrous tissues.
5.GLIOMA – These cancers develop in the network of
supporting connective tissues in the brain and the central
nervous system.
6.MELANOMA
A. This is a pigmented tumour.
B. It originates from the pigmented moles on the skin.
C. If theses moles are irritated, they rapidly become
malignant.
7. LYMPHOMA – Cancer from lymph nodes and other tissues
of the lymphatic system.
8.TERATOMA – Arises from the morula stage itself.

23. Cancer Cell
It is an abnormal cell that doesn't follow this cycle.
Instead of dying off as they should, cancer
cells reproduce more abnormal cells that can
invade nearby tissue. They can also travel
throughout the blood and lymph systems to other
parts of the body.
FORMATION
Cancer develops when the body's normal control
mechanism stops working. Old cells do not die and
instead grow out of control, forming new,
abnormal cells. These extra cells may form a mass
of tissue, called a tumor.

24. • CARCINOGENESIS
It also called oncogenesis or tumorigenesis, is
the formation of a cancer, whereby normal
cells are transformed into cancer cells. The
process is characterized by changes at the
cellular, genetic, and epigenetic levels and
abnormal cell division.

25. DIAGNOSIS
• Cancer is nearly always diagnosed by an expert who
has looked at cell or tissue samples under a
microscope.
• In some cases, tests done on the cells' proteins,
DNA, and RNA can help tell doctors if
there's cancer.
• These test results are very important when
choosing the best treatment options

26. Signs of Cancer
• Change in bowel or bladder habits.
• A sore that does not heal or heal and returns
• Unusual bleeding or discharge.
• Thickening or lump in the breast or elsewhere.
• Indigestion or difficulty in swallowing.
• Obvious change in a wart or mole.
• Nagging cough or hoarseness.
• Alternating constipation and diarrhoea
• Unexpectable loss of weight.

27. BIOPSY
• It is a technique by which a suspected cancer tissue
can be tested. It consists microscopic examination.
X RAY
It is used to diagnose digestive tract, kidney and
chest.