Chapter 8.5 - Cancer

Question 1

Cancer is a disease of the _____ ______ _______ system. What is this system?

Answer 1

The cell cycle control system.
A cyclical system that contains checkpoints and regulates the cell cycle. It’s run by proteins that provide signals.

Question 2

Where are the three major checkpoints in the cell cycle? What happens at checkpoints?

Answer 2

At Gap 1, Gap 2 and Metaphase (between anaphase and metaphase).
Cells stop at these checkpoints and do not proceed with division unless signalled to.

Question 3

What is the non-dividing state of a cell called? When in the cell cycle does a cell enter this state? Can cells leave this state?

Answer 3

G0 (G zero)
These cells do not pass the G1 checkpoint and instead stay in a non-dividing state (i.e. muscle and nerve cells).
Yes, the right growth factor can tell a cell to start dividing again.

Question 4

What is a signal transduction pathway?

Answer 4

A series of protein molecules that convey a message (such as growth factors). It’s like a game of telephone.

Question 5

What makes cancer cells different from normal cells?

Answer 5

Cancer cells do not obey the normal signals that regulate the cell cycle. They divide continuously (even without growth factors), ignore checkpoints and may invade other tissues of the body. As long as they have nutrients they can be immortal.

Question 6

How does the first cancer cell form in the body? How does the immune system react?

Answer 6

A normal cell will convert to a cancer cell due to a mutation in a gene(s) related to the cell cycle control system.
The immune system will usually recognize and destroy these abnormal cells.

Question 7

What is tumour?

Answer 7

An abnormally growing mass of body cells that form a lump.

Question 8

What are the two general types of tumours? What makes them different? Which one is considered cancerous?

Answer 8

Benign tumours remain at the original site. Usually fully removed by surgery.
Malignant tumours invades neighbouring tissues, spread to other body parts, and can draw blood vessels towards themselves. They are considered cancerous.

Question 9

What is metastasis?

Answer 9

The spread of cancer cells beyond their original site (as in the case of malignant tumours).

Question 10

______ are the most common cancers. What body parts do they affect?

Answer 10

Carcinomas.
Cancers that originate in the external or internal covering of the body, such as the skin or the lining of the intestine.

Question 11

What are some ways tumours can be treated?

Answer 11

Tumours are often surgically removed. Radiation treatments may also be given. Radiation will tend to damage cancer DNA more than normal cells because the cancer cells are growing more rapidly.

Question 12

Cancers that have metastasized are treated with _________ .

Answer 12

Chemotherapy.

Question 13

How do two common examples of chemotherapy work? Where were they discovered?

Answer 13

These drugs work by freezing or preventing the mitotic spindle from forming, which stops cells from dividing.
Both were discovered in plants!

Question 14

Besides surgery, radiation treatment, and chemotherapy, how else can cancer be treated?

Answer 14

Hormonal treatments, specific inhibitors, antibodies, biological response modifiers, vaccines etc.
All of these are related to proteins and signals that affect cancer cells.

Question 15

What is angiogenesis?

Answer 15

A process that rapidly dividing cancer cells use to stimulate the formation of new blood vessels towards them.

Question 16

A virus can cause cancer How does this happen? What are some examples in humans?

Answer 16

A virus can insert their nucleic acid (DNA or RNA) into the DNA of
host chromosomes.
Hepatitis B, Human papillomavirus, H. pylori bacterium (that causes stomach ulcers) are linked to cancer.

Question 17

What is an oncogene? What causes oncogenes?

Answer 17

A cancer causing gene.
Can be made by a viral gene being inserted into your cell’s DNA or by a mutation in your own genes.

Question 18

What is a proto-oncogene?

Answer 18

A normal, healthy gene that, if changed, can become a cancer-causing oncogene.
Many proto-oncogenes code for growth factors (specific proteins) or other parts of the cell cycle.

Question 19

How do proto-oncogenes become oncogenes?

Answer 19

It may mutate to code for a hyperactive protein.
May create multiple copies of itself so more protein is made.
May be moved to a new location on the DNA where it is promoted (transcribed more often than normal).

Question 20

How can genes that prevent cell division contribute to cancer?

Answer 20

aka. Tumour-suppressor genes
If a mutation decreases the activity of these genes then tumours can form from lack of suppression (instead of from stimulation).

Question 21

How many mutations do most cancers require for a cell to become fully cancerous? Do a couple mutations always develop into cancer?

Answer 21

4 or more mutations.
It’s possible that only one or two mutations occur and cancer never develops or that the immune system recognizes and destroys mutated cells.

Question 22

Why are older people affected more by cancer?

Answer 22

Cancers take a long time to develop, so older people have had more time to accumulate mutations.

Question 23

There are three basic kinds of tumours, they are:

Answer 23

Benign non-cancerous, doesn’t spread.
Precancerous Could become cancerous or not.
Cancerous spreads and metastases.

Question 24

There are 5 types of pre-cancerous tumours, they are:

Answer 24

Hyperplasia – normal looking cells that grow faster than normal.
Atypia – slightly abnormal cells.
Metaplasia – Normal cells in the wrong place.
Dysplasia – overly abundant abnormal cells. These are precancerous.
Carcinoma in situ – most severe type, cells are very abnormal but haven’t spread.
HAMDC

Question 25

How does a mutated ras gene affect cell division?

Answer 25

The mutated ras gene codes for a hyperactive version of the ras protein (a relay protein) that makes the cell divide even in the absence of growth factor. It relays a message even when it shouldn’t.
Summary: overstimulates cell growth.

Question 26

How does a mutated p53 gene affect cell division?

Answer 26

A mutation produces a faulty transcription factor which prevents a cell from making a protein that inhibits cell division , resulting in excessive cell division.
Summary: fails to stop cell growth.

Question 27

The ras gene is implicated in ___ % of cancers and the p53 gene in more than ___ % of cancers.

Answer 27

Ras gene = 30%
p53 gene = 50%

Question 28

When cancers can runs in a family, what are people actually inheriting?
Are most cancers caused by this?

Answer 28

An oncogene or a mutant allele of a tumour suppressor gene. It’s one step closer to cancer but doesn’t guarantee cancer.
No, most cancers are caused by environmental factors not inherited mutations.

Question 29

What is a carcinogen?

Answer 29

A cancer causing agent. Factors that alter DNA and make cells cancerous

Question 30

What is a mutagen?

Answer 30

A substance that cause mutations.

Question 31

Most mutagens are also _________

Answer 31

Carcinogens

Question 32

Two very potent mutagens are _______ and _____________

Answer 32

X-rays and ultraviolet (UV) radiation (present in sunlight).

Question 33

The one substance known to cause the MOST cases and types of cancer is ___________

Answer 33

Tobacco.

Question 34

It often takes _________ of exposure to carcinogens before enough genetic changes accumulate to cause cancer.

Answer 34

Decades.

Question 35

What food choices reduce cancer risk?

Answer 35

Getting enough vitamins, fibre, reducing animal fat, getting sulphorophane in cruciferous veggies can help prevent certain cancers. Eat healthy!

Question 36

What is the stem cell theory of cancer?

Answer 36

That even if we physically remove or shrink the majority of a tumour with chemotherapy or radiation the cancer may come back unless we have removed the cancerous stem cells.

Question 37

How can errors in fibroblast growth factor (FGF) cause cancer?

Answer 37

FGF is involved in cellular communication. Errors in how it’s transmitted and received by cells can activate dormant stem cells in an organ that can cause cancer.

Question 38

What are telomeres? What is telomerase? How is this related to cancer?

Answer 38

DNA structures at the end of chromosomes that shorten as cells age eventually preventing cell division. Telomerase is an enzyme that controls telomere length and can add more telomeres to the chromosomes. Most cancer cells can produce this enzyme and essentially become immortal.

Question 39

List 5 things you can do to reduce your risk of getting cancer. What is the #1 thing you can do?

Answer 39

.#1 Don’t smoke, exercise, eat fruits and veggies, reduce red meat intake, maintain a healthy weight, be active, reduce sun exposure, and get routine testing that can detect cancers early.

Question 40

The chance of Canadians getting cancer in their lifetime is 2 in ____. The chance that they will die from cancer is 1 in ____ .

Answer 40

2 in 5 Canadians will develop cancer.
1 in 4 Canadians will die from cancer.

Question 41

The leading cause of death is Canada is _________

Answer 41

Cancer.

Question 42

What type of cancer is the leading cause of cancer death?

Answer 42

Lung cancer is the leading cause of cancer death.

Question 43

What is the most common type of cancer in females?

Answer 43

Breast cancer is the most common form of cancer in females.

Question 44

Almost 90% of Canadians who develop cancer are over the age of ____

Answer 44

50

Question 45

Based on survival rate, the best type of cancer is ______ cancer and the worst is ________ cancer.

Answer 45

Best: thyroid and testicular cancer (97% 5-year survival rate)
Worse: pancreas (10% 5-year survival rate)

Question 46

Why is the survival rate for pancreatic cancer so low?

Answer 46

It usually does not cause any symptoms until an advanced stage and it tends to be a highly aggressive form of cancer.

Question 47

What are the 6 most notable risk factors for cancer?

Answer 47

Smoking, unhealthy lifestyle, sunlight and tanning beds, alcohol, cancer-related infection (viruses), environmental and occupational carcinogens.
SUSAVE

Question 48

Why is early detection of cancer important?

Answer 48

It makes the potential for successful treatment much greater, which is why it is important to screen for cancer.

Question 49

If cancer rates have been declining overall, why have the number cancer cases and deaths increased?

Answer 49

Increases in cancer cases and deaths are related to an aging and growing population.

Question 50

Differences in survival rates of different cancers are due to:

Answer 50

The stage and aggressiveness of the cancer at diagnosis;
Availability of early detection, diagnostic and treatment services.

Question 51

What are the 4 basic stages of precancer/cancer?

Answer 51

Stage 0 – abnormal cells; carcinoma in situ – not yet cancer.
Stage 1 – Cancer is small and only spread a little into local tissue.
Stages 2 and 3 – Cancer is larger and has spread to nearby tissues.
Stage 4 – Cancer has metastasized to other body parts – referred to as metastatic cancer

Question 52

What are the ABCDEs of identifying melanoma?

Answer 52

Asymmetry
Border (irregular, poorly defined)
Colour (varies between areas)
Diameter (get it checked if it is 6 mm or larger)
Evolving (changes in size, shape, colour etc.)