Lecture 1 & 2

Question 1

What is cancer?

Answer 1

• a collection of related diseases of proliferation
• some of the body’s cells begin to divide without stopping and spread into surrounding tissues
• cancer cells are less specialized than normal cells

Question 2

What is the leading cause of death in Canada?

Answer 2

Cancer is responsible for 29.9% of the deaths in Canada

Question 3

In the levels of the skin, what are the various kinds of cancer found in the cell types?

Answer 3

Basement membrane - carcinoma
Fibroblast and epithelial cells - sarcoma
Blood cells - Leukaemia

Question 4

What are some of the Canadian Cancer Statistics from 2013?

Answer 4

• About 850000 Canadians were alive at the beginning of 2009 with a cancer diagnosed in the previous 10 years
• 2 in 5 Canadians will develop cancer in their lifetime
• 187600 Canadians will be diagnosed with cancer in 2013
• 63% is the likelihood of Canadians with cancer surviving 5 years relative to the general population
• 1 in 4 Canadians will die of cancer
• 75500 Canadians will die of cancer in 2013

Question 5

How is the geographical distribution of cancer relevant to the cause of it?

Answer 5

Geographical variation indicative of environmental, genetic, behavioural, natural causes, etc.

Canada (leukaemia), USA (colon), Brazil (Cervical), UK (Lung), China (Liver), Japan (Stomach) and Australia (Skin)

Question 6

What is a tumour?

Answer 6

Any abnormal growth (neoplasm) or mass of tissue which exceeds and is uncoordinated with that of normal tissue and persists in the same excessive manner after the stimuli, which evoked the change, is removed
- may be benign or malignant

Question 7

What are examples of stimuli?

Answer 7

Growth factors, infection, the microenvironment, etc.

Question 8

What are the microscopic differences between benign and malignant tumours?

Answer 8

Nuclear size - small vs. Large (due to the increase in DNA synthesis)
N/C ration (ratio of nuclear size to cytoplasmic volume) - low vs high
Nuclear shape - regular vs pleomorphic (irregular shape)
Mitosis index (relative number of dividing cells) - low vs high
Tissue organization - normal vs disorganized
Differentiation - well differentiated vs poorly differentiated (anaplastic)
Tumour boundary - well defined (encapsulated) vs poorly defined

Question 9

What is metastasis?

Answer 9

The process through which the cancer establishes itself at another site(s)

• invade surrounding tissues and vessels
• then transported Bt the circulatory system to distant sites
• reinvade and grow in a new location

Question 10

Where does prostate, small cell lung, neuroblastoma and breast cancers frequently metastasize? Why?

Answer 10

Bone
Brain
Liver
Liver
Due to how the blood circulates, liver for example is where the blood is filtered.

Question 11

What is the hypothesis given by Seed and Soil about cancers frequently metastasizing to specific sites?

Answer 11

Certain tissues or organs are particularly favourable for the growth of some cancers

Question 12

Why do some think capillary bed entrapment is the reason for some cancers metastasizing in certain tissues frequently?

Answer 12

Organ preference is a function of entrapment of cancer cells in the first capillary bed encounter

Question 13

What are the 4 kinds of cell growth?

Answer 13

Hypertrophy, hyperplasia, dysplasia and neoplasia

Question 14

What is hyper trophy?

Answer 14

Cells increase in size with normal organization

Caused by external stimuli and is reversible

Question 15

What is hyperplasia?

Answer 15

Increase in cell number with normal organization

Caused by external stimuli and reversible

Question 16

What is dysplasia?

Answer 16

Disorganized growth (may or may not be reversible)

Question 17

What is neoplasia?

Answer 17

Disorganized growth
There is a net increase in number of dividing cells
No stimuli required and not reversible

Question 18

Does the size of tumour determine its malignancy?

Answer 18

Size does not determine how malignant a tumour is

Question 19

Can you die from a benign tumour?

Answer 19

Usually no, but it does depend on where in the body the tumour is.

Question 20

Provide some examples on why there is poor correlation between cancer and cell division frequency.

Answer 20

• brain cells divide rarely, yet the tumours in the supporting tissue can be frequent
• small intestinal tumours are rare yet the average human produces ~40kg of gastrointestinal cells/year and 10kg of white blood cells (rapid growth)
• a human fetus requires 9 months to achieve a weight of 4kg while a patient can die from a tumour that is less than 5kg that took years to develop

Question 21

What is the major cause of tumour growth?

Answer 21

Imbalance between cell division, cell death and cell differentiation

• differentiation is the hallmark of cancer prevention
• cell death pathways are not being regulated

Question 22

What are the ratios of cell birth to cell death in a normal cell and a tumour cell?

Answer 22

Normal - 1 born : 1 dies

Tumour - ratio altered - too much cell birth to too little cell death

Question 23

In what types of cells does cancer arise?

Answer 23

Stem cells, restricted-potential stem cells and progenitor cells.