with full of photos , simple and convenient learning & prepared by student of biotechnology

1. Rupen Chakma (17/BBT/11)
Bipasha Roy (17/BBT/24)

2. CONTENTS
 INTRODUCTION
 PROPERTIES
 CLASSIFICATION
 THEORIES
 REASONS FOR MUTATION
 HOW MUTATIONS CAUSE TUMOR
 REPAIR AND ANTI CANCER MECHSNISM
 RUNAWAY MECHANISM AND DIAGNOSIS
 CONCLUSION
 REFERENCE

3. What is a tumor ?
In spite of several check points in a cell cycle to
check any modifications in DNA before its
transfer to next generation, certain mutations
takes place in DNA leading to loss of certain
characters and control over its multiplication
rate.
The consequences of these modification result
in pathological over growth of modified tissues
generally referred as TUMOR or Neoplasia
(meaning new formation) or “cancer”.
There are two types of Tumors : Benign
tumors and Malignant Tumors.

4. BENIGN TUMORS :
• Benign tumors are generally not harmful due to their well-
defined growth with smooth boundaries.
• Simply grow in diameter and restricted to one place but can be
harmful if the tumor compresses the surrounding tissue against a
hard surface in the body.
• Usually grows at a relatively slow pace and may stop growing for a
time when it reaches a certain size.
• A complete cure can usually be achieved by removing the
abnormally grown tissue mass.

5. MALIGNANT TUMORS :
• The Malignant tumors are dreadful because their growth is not
restricted to one place.
• Their metastasis nature helps their spread from one place to other
locations in the body via lymph or blood.
•Unlike benign malignant tumors are properly referred to as
“Cancers”.
 The origin of the word cancer is credited to the Greek physician
Hippocrates (460-370 B.C.). In Greek cancer refers to a crab. It is
most likely applied to the disease to mind the shape of a crab,
because of finger – like projections spreading from a cancer tissue
mass resembles the structure of crab more over the spread of cancer

6. Altered biological properties of cancer cells
1) Acquistion of self-sufficiency in growth signals.
2) Loss of sensitivity to anti-growth signals.
3) Loss of apoptosis, in order to allow growth despite genetic
errors and external anti-growth signals.
4) Loss of senescence, leading to limitless replicative
potential (Immortality).
5) Acquistion of sustained “angiogenesis” (Growth of new
blood vessels from pre-existing vessels).
6) Acquistion of ability to invade neighbouring tissues, the
defining property of invasive carcinoma.
7) Acquistion of ability to metastases at distant sites, the
classical property of malignant tumors.

7. Classification of Tumors:
Since development of tumor is possible in any region or
organ of the body with dividing cell, tumors were broadly
classified into 3 basic types based upon the embryonic origin
of the tissues involved in the formation of tumor.
They are :
1. CARCINOMAS
2. SARCINOMAS
3. LEUKEMIA

8. 1.Carcinomas
• Developed from cells of ectodermal or endodermal origin.
• They invade surrounding tissues and organs and may
metastasize, or spread, to lymph nodes and other sites.
• Based upon the histopathological appearance they can be
differentiated into “Aden carcinoma” and “squamous cell
carcinoma” to reflect the involvement of glandular or squamous
cells in tumor formation.
• Approximately 90% of human cancers are malignancies of
epithelial cells.

9. 2.Sarcomas (From the Greek ‘sarx” meaning “flesh”)
• Developed from connective tissue or mesoderm.
•Cancers of breast, colon, pancreas bones etc. comes under
this type.
• Sarcomas are rare in humans; about 2% of human cancers
come under this category.

10. 3.Leukemia (Greek leukos “white” ; aima “blood”)
•Developed from bone marrow tissue or in blood.
•Characterized by an abnormal proliferation of blood cells, usually
white blood cells (leukocytes).
•Leukemia tumor is subdivided into lymphoblastic or
lymphocytic leukemia and myeloid or myelogenous leukemia
according to the blood cells affected.
To make it understandable to a common man, tumors were generally
named after the organ or tissue from which it has been developed. For
example, cancer developed in breast tissue is referred as breast cancer.
Similarly, lung cancer, colon Cancer, gastric cancer, skin cancer etc.

11. William Williams Keen

12. Different theories to explain cancer development :
From the earliest times, physicians have wondered about
the cause of cancer.
 The Egyptians blamed Gods for the development of
cancers.
Several theories were proposed by different scientists to
explain the cause for cancers. Some of them are as follows :
1. HUMORAL THEORY
2. LYMPH THEORY
3. BLASTEMA THEORY
4. CHRONIC IRRITATION THEORY
5. TRAUMA THEORY
6. PARASITE THEORY

13. Humoral theory:
 Hippocrates believed that the body contained four humors (Body
fluids) – blood, phlegm, yellow bile, and black bile.
 A balance of these fluids resulted in a state of health. Any excesses
or deficiencies caused disease
 An excess of black bile collecting in various body sites was
thought to cause cancer.
This theory of cancer was passed on by the Romans and was
embraced by the influential doctor Galen”s medical teaching, which
remained unchallenged through the middle Ages for over 1300 years.
During this period of the body, including autopsies, was
prohibited for religious reasons, thus limiting knowledge

14. Lymph Theory:
 Among the theories that replaced the humoral theory of cancer
was cancer’s formation by another fluid – lymph.
Stahl and Hofman theorized that the cancer was composed of
fermenting and degenerating lymph varying in density, acidity and
alkalinity.
 The theory gained rapid support. John Hunter(1723-1792) agreed
that tumors grow from lymph constantly thrown out by the blood.
Blastema Theory:
In 1838, German pathologist Johannes Muller demonstrated that
cancer is made up of cell and not lymph. But he was of the opinion
that cancer cells did not arise from normal cells.
 Muller proposed that cancer cells arose from budding elements
(Blastema) between normal tissues.
Muller’s students Rudolph including cancer cells, are derived from
other cells.

15. Chronic Irritation Theory:
Virchow proposed chronic irritations as the cause of cancer, but he
falsely believed that cancers “spread like a liquid.”
 A German surgeon, Karl Thiersch, showed that cancers
metastasize through the spread of malignant cells and not through
some unidentified fluid.
Trauma Theory:
Despite advances in the understanding of cancer, from the late
1800s until the 1920s, cancer was thought by some to be caused
trauma.
Parasite Theory:
In the 17th and 18th centuries, some believed that cancer was
contagious. In fact, the first cancer hospital in France was forced to
move from the city in 1779 because of the fear of the spread of cancer
throughout the city.

16. Reasons for tumor formation:
Oncogenes, activate cell division and influence embryonic
development and tumor suppressor genes halt cell division.
Since these two genes are typically found in normal human
cells, certain mutations in them may transform their normal
function resulting in the conversion of normal cells into
tumor cells. Either inherited defects or acquired mutations
due to exposure to carcinogens may cause conversion of
normal cell into a tumor cell.

17. How mutations cause Tumor: Due to mutations, some of the
regular genes may fail to code proteins essential for regulation
of cell cycle, Synthesis of proteins involved in the regulation
of cell cycle are essential to stop access of defective or altered
DNA to the daughter cells. Failure in regulation of cell cycle
results in accumulation of mutations or abnormal characters
in the daughter cells. The normal gene gradually lost its
original characters and become a tumor gene and its modified
tumor gene is known as “Proto-oncogene”. After several
divisions the cell with Proto-oncogene produces tumor.
Mutations may also suppress the efficiency of certain tumor
suppressor genes, as a result chances for tumor development
increases.
Of the many known oncogenes some are derived from normal
Proto-oncogenes. For example the Ros gene that encodes a
protein essential for intracellular signal transduction in

18. normal cells becomes an oncogene due to mutations and
starts encoding a protein that acts as a signaling molecule for
excessive or uncontrolled growth of cells. An oncopotein
encoded by an oncogene may be similar to the normal
protein but excessive production may alter the character of
normal cells and induces conversion of a normal cell into a
tumor cell.
Others things that may increase the chance of
developing tumors are-
1. Radiation: High- frequency radiation, such as ultraviolet
and ionizing radiation, damages the genetic material DNA,
possibly inducing genetically transferable abnormalities.
2. Viruses: Some human retroviruses and papilloma viruses
exhibit carcinogen gene sequence potential. Retrovirus may
convert proto-oncogenes into oncogenes either by altering or
condensing, to code proteins with abnormal activity or

19. controlling with powerful regulators to induce the
production in excess or in inappropriate circumstances.
3. Hormones: The role of hormones in carcinogenesis is still
controversial, but it seems that, excessive use of some
hormones, especially estrogen, produces cancer in animals.
4. Chemical substances: Some of the chemical substances
that can induce carcinogens include:
Alkylating agents-leukemia,
Aromatic hydrocarbons and benzopyrene ( From polluted
air) - lung cancer,
Tobacco – cancer of the Lung, oral cavity etc

20. Repair and Anti-cancer mechaniSM of body
Cell shredding: The body simply shreds some types of cells
that are particularly exposed to environmental carcinogens.
For example, intestinal epithelial cells are shed frequently, so
that any mutations do not get a chance to reproduce. Cell
shedding generally occurs in the stomach, colon, skin, and
other areas.
Cell division limits: Telomeres limit the number of cell
divisions that a single cell can under go, this character helps in
the inhibition of the growth of tumor cells. If a normal cell
becomes cancerous, its clones often die out to telomeric
restriction before producing significant tumor.
Carcinogens neutralization: Carcinogenic substances are
quickly metabolized into harmless substances by the gut and
liver in healthy individuals.

21. Run away mechanisms of tumor cells:
• Sneaking Through: Newly formed tumor cells escape
immune system’s attack by sneaking, till they increase their
number to resist the immunological response
Some tumors posses weak immunogenicity.
• Modulating Tumor Ags: Here the tumor cells pull the
newly formed Ags to interior(Cytoplasm) or stop expressing
in surface Ags. In the absence of these Ags immune system
fails to enforce any action against the tumor cells.
• Masking Tumor Ags: Certain tumor cells produce
mucoproteins coat known as Sialomucin coat to hide their
new Ags.
• Tumor induced tolerance: Certain tumor cells induce

22. tolerance through synthesizing different immuno
suppressants to suppress or activate TS-cells which in turn
inhibit the activity of TC ,TD and B-cells activity.
 Production of blocking agents: Producing auto
antibodies known as “blocking antibodies” against their own
antigen.
 Alternation of cell adhesion molecules: Newly formed
tumor cells alter their expression of cell adhesion molecules
to reduce stable contact formation with cytotoxic cells.

23. DIAGNOSIS:
•Surgery: benign tumors can be removed entirely by
surgery.
•Chemotherapy: by using suitable drugs.
•Radiation Therapy: using ionizing radiation to kill
tumor cells.
•Hormonal Therapy: inhibiting by hormones – breast,
prostate.
•Targeted therapy: interfering with specific molecules
needed for carcinogenesis

24. Conclusion
 Tumors are uncontrolled growth of cells occurs due to
mutation in different stages of cell cycle
 Two types- Benign and Malignant
 Tumors can occur due to mutation, radiation,
chemicals, viruses etc.
 Although some tumors are mostly fatal we can get rid
of certain tumors through different diagnosis like
surgery, chemotherapy etc.

25. REFERENCE
 THE ELEMENTS OF IMMUNOLOGY – Fahim
Halim Khan
 A TEXTBOOK OF IMMUNOLOGY – Dr. P.
Madhavee Latha, S Chand publication
 medicalnews.com
 macmillan.org.uk

26. THANK YOU
Fight cancer with a smile