Cancer Biology**

Question 1

What are characteristics of a Benign tumour?

Answer 1

• Slow growing
• Well-organized
• Differentiated (known origin)
• Generally non-destructive (not harmful)
• Rarely cause death

Question 2

What are the characteristics of a Malignant tumour?

Answer 2

• Fast growing
• Unorganized
• Loss of differentiation
• Increased invasiveness
• Ability to kill host tissue
• Usually cancerous

Question 3

Explain the benign and malignant tumour continuum

Answer 3

A benign tumour can have characteristics that lead towards malignant and become benign, but malignant tumours cannot become begign

Question 4

What are Carcinomas?

Answer 4

Solid mass/tumours that originate in the epithelial cells (lining of all tissues)
- Most common cancer cases, 85-90% of all cancers are carcinomas

Question 5

What are Melanomas?

Answer 5

• Originates in melanocytes (can be apparent as a mole or can be found in the eye)
• Most commonly found on skin
• Most serious type of cancer

Question 6

What is the difference between a melanoma skin cancer and a non-melanoma skin cancer?

Answer 6

Melanoma - more deadly and have the ability to spread
Non-melanoma - More common but not deadly and cannot spread

Question 7

What are Sarcomas?

Answer 7

Solid tumours found in connective tissues, bones, muscles, cartilage and fat (soft tissue sarcomas or osteosarcomas)
- Account for less than 2% of all cancers

Question 8

Are sarcomas life threatening?

Answer 8

Yes, the survival rate is not great.
- Can lead to amputations due to osteosarcomas (more common in younger ages)

Question 9

Where are osteosarcomas found?

Answer 9

Typically in long bones - Femur, Tibia, etc - but can form on any bone
- Small and hard to detect

Question 10

What is Leukemia?

Answer 10

Non-solid type of cancer that forms in blood organs (Bone marrow, lymphatic system)

Question 11

What are the two main types of leukemia?

Answer 11

1. Acute - Sudden onset
2. Chronic - Slow onset, low grade level for a long period of time

Question 12

How else can leukemia be classified?

Answer 12

Based on cell types
- Myeloid (myelogenous leukemia)
- Lymphocytes (lymphocytic leukemia)

Question 13

What are Lymphomas?

Answer 13

Non-solid cancer of the lymphocytes that results in enlargement of lymph nodes
- 5% of cancers are lymphomas

Question 14

What are the two distinct lymphoma groups?

Answer 14

1. Non-Hodgkin’s Lymphoma (NHL) > throughout the lymphatic system, quick to progress but hard to treat
2. Hodgkin’s Lymphoma > Progress through lymphatic system one node at a time, easier to treat

Question 15

What is the origin of cancer?

Answer 15

Cancer develops from normal cells

Question 16

Is cancer an invader?

Answer 16

No, cancer does not invade cells it forms within them however invaders like viruses/bacteria may promote cancerous cell growth

Question 17

Do all cells in tumours have the same characteristics?

Answer 17

Cells within a tumour all have the same genetic makeup

Question 18

How can you determine the origin of cells in a tumour?

Answer 18

Because of their genetic makeup, all cells in a tumour are developed in one single cell. Their genetics determine their origin cell

Question 19

How does a tumour arise?

Answer 19

From a series of mutations in the original cell and progeny of the cell

Question 20

What is a mutation?

Answer 20

Permanent changes in DNA

Question 21

How many mutations in specific genes does it take to produce a tumour?

Answer 21

6 independent mutations to a specific gene to produce a tumour (can occur over years of time)

Question 21

What is the mutation rate in Humans?

Answer 21

1 in 1 million genes per cell generation (most harmless or cell repairs self)

Question 22

How do mutations occur?

Answer 22

• Inherited (genetics)
• Arise during DNA replication and recombination
• Caused by mutagens

Question 23

What are mutagens? Give examples

Answer 23

A mutagen is an environmental agent that cause mutations
- UV rays = risk of skin cancer
- Pollutants (air, work place substances)
- Smoking = risk of lung cancer

Question 24

What can genetic mutations result in?

Answer 24

Results in the activation of oncogenes

Question 25

What does the activation of oncogenes do?

Answer 25

Increases the chance of developing cancer

Question 26

What are oncogenes?

Answer 26

Excessively active versions of normal cellular genes called proto-oncogenes

Question 27

What do proto-oncogenes do?

Answer 27

Parts of DNA that - Control cell division - Cell death - Other cell functions

Question 28

What happens if proto-oncogenes don't work properly?

Answer 28

Become oncogenes which - causes increase in uncontrolled cell division - Potential problems with cell death - Increases the risk of cancer

Question 29

What do oncogenes do to increase risk of cancer development?

Answer 29

Leads to excessive proliferation (cell division) and problems in signalling cell apoptosis (cell death) - Cancer is rarely caused by one activation of a single oncogene (usually multiple)

Question 30

What does a tumour suppressor do?

Answer 30

Normally they suppress oncogenes by controlling excessive cell division

Question 31

What happens when there is a mutation in tumour-suppressor genes?

Answer 31

Typically less of function of t-s genes, therefore there is nothing suppressing oncogenes

Question 32

How can a person have inactive tumour suppressor genes?

Answer 32

1. Most commonly inactivation is associated with inherited cancers 2. Can also be sporadic (by chance) and not inherited

Question 33

What is an example of a sporadic tumour cancer suppressor?

Answer 33

Wilm's tumour

Question 34

What is Wilm's Tumour (nephorblastoma)?

Answer 34

- It's a tumour that originates in cells of the kidney - Most common Kidney (renal) cancer

Question 35

What is the cause of Wilm's Tumour?

Answer 35

Caused by mutations in kidney cells in utero (embryonic tumour) = Paediatric tumour - Most are not inherited but rather sporadic

Question 36

What population does Wilm's Tumour affect?

Answer 36

- Children up to age 10 - Majority affects age 43 months - 48 months - Accounts for 6% of all childhood cancers (1 in 10,000 live births) - 90-95% of cases are in a single kidney, can happen in both (commonly inherited)

Question 37

What are the 4 gene types associated (mutated) in Wilm's Tumour?

Answer 37

TP53 - classic tumour suppressor gene CTNNB1 - classic oncogene WTX - tumour suppressor gene WT1 - similar to tumour suppressor gene

Question 38

What are properties of tumour cells?

Answer 38

- Proliferate (divide) indefinitely - Less cell adhesion (sticking together) - Ability to continue growing despite crowding - Reduced apoptosis (cell death)

Question 39

What is Metastasis?

Answer 39

Migration of cancer cells from the original tumour site through the blood and lymph to other tissues

Question 40

Why are metastases so crucial in relation to cancer?

Answer 40

Without metastasis, cancer would be harmless. Metastasis is a major cause of death

Question 41

Is metastasis growth random?

Answer 41

No. Main thing to remember is each different type of cancer has a specific site where metastasis form. E.G: Liver cancer can form metastasis in the lungs but it's still considered liver cancer because of it's origin

Question 42

What must be in place for metastatic cells to be successful?

Answer 42

1. Angiogenesis 2. Motility 3. Alterations in cell adhesion 4. Secretion of proteolytic enzymes 5. Ability to escape immune surveillance

Question 43

What is Angiogenesis?

Answer 43

The development of new blood vessels to supply blood needed for primary tumour growth

Question 44

Why is angiogenesis related to metastatic cells?

Answer 44

New blood vessels provide a route for metastatic cells to escape into the blood and travel to another part of the body - The degree of angiogenesis determines likelihood of metastases, more blood supply = more chance of metastases

Question 45

What is Motility?

Answer 45

The ability of a cell to move under its own power

Question 46

Why is motility related to metastases?

Answer 46

It's needed in order for a tumour cell to leave the primary tumour and circulate throughout the blood or lymphatic system

Question 47

What is Cell Adhesion?

Answer 47

Allows cancer cells to stick to extracellular matrix and not to other cells allowing metastases to adhere successfully to other structures/organs

Question 48

What do Proteolytic Enzymes do?

Answer 48

Secreted by cancer cells to break down barriers such as: - Basement membrane - Extracellular matrix - Endothelial barrier

Question 49

Why are proteolytic enzymes important for metastases?

Answer 49

Need to break down barriers to get into circulation and the new tumour bed to settle and continue growing

Question 50

What immune system cells do cancer have to escape from? (cells that kill off disease)

Answer 50

1. Cytotoxic T lymphocytes 2. Activated macrophages 3. Natural killer cells

Question 51

What is the Metastatic Cascade?

Answer 51

Primary Tumour forms > Angiogenesis and Invasion > Survival in Circulation > Tumour Cells Arrest in Capillary Bed of Organ > Establishment of Secondary Tumour