S1: What is cancer?

Question 1

What is cancer?

Answer 1

Cancer is the name for a group of diseases characterised by uncontrolled proliferation and spread of abnormal cells

Question 2

What is a tumour?

Answer 2

The abnormal cells proliferate to form a mass of tissue called a tumour.

Question 3

What do abnormal cells do?

Answer 3

• multiply and form a tumour

- invade neighbouring tissues and spread throughout the body to form distant tumours

Question 4

How are cancers classified?

Answer 4

They are classified according to tissue of origin

Question 5

Name the 4 classes of cancers

Answer 5

Carcinoma (epithelial origin)

Sarcoma (connective tissue)

Lymphoma (lymphoid tissue)

Leukemia (Blooc cells and blood forming cells)

Question 6

What is the most common class of cancer and why?

Answer 6

Carcinoma’s

This is probably because the epithelia are actively dividing cells and they are most exposed to external damage

Question 7

What is cell turnover?

Answer 7

This is when a cell grows, matures and then performs its function for a period of time and then die.

The rate of turnover depends on the cell as certain cells don’t turnover (e.g. brain cells).

Question 8

What are the characteristics of cancer cells?

Answer 8

• Increased cell growth and proliferation in the absence of stimuli
• Decreased cell death
• Decreased cell maturation (decreased differentiation, they behave like immature cells)
• Invade and spread

Question 9

What are tumours which aren’t cancerous called?

Answer 9

Benign
They do not invade surrounding tisue

e.g. polyps in our colon

Question 10

What are characteristics of benign tumours?

Answer 10

• Non invasive
• Growth is usually self limiting
• Can grow into malignant cancers
• Can be dangerous if it presses on a vital structure e.g. brain

Question 11

Benign vs Malignant

Answer 11

If the margins of the tumour are well-defined and growth is entirely local, the tumour is benign (this does not mean they are always harmless).

If the margins of the tumour are poorly defined and the cancerous cells extend into, invade and destroy surrounding tissues then the tumour is malignant.

Question 12

When diagnosing cancer using histopathology, what are scientists looking for?

Answer 12

• Abnormalities of cells (cytology)
• Abnormalities of tissue structure
• Evidence of invasiveness

Question 13

How does metastases occur?

Answer 13

As the cell ebcoems more invasive, the cells eat their way through the basement membrane (by proteolysis) and start to spread through the body (become motile)

Question 14

How does cancer spread to the regional lymph nodes and distant parts of the body?

Answer 14

Local spread occurs through the lymphatic system to the regional lymph nodes
Distant spread to further parts of the body occurs through the blood circulation

Question 15

What are distant tumours called?

Answer 15

Metastases (singular: metastasis)

Question 16

How can the origin of a metastases be found?

Answer 16

Looking at cells by doing a biopsy and then looking at a histeopathology

Question 17

What are the commonest cancer in men and women in the UK?

Answer 17

MEN
Prostate
Lung
Colorectal
Bladder

WOMEN
Breast
Colorectal
Lung
Ovary
Uterus

Question 18

What are the risk factors that can cause cancer?

Answer 18

• Increasing age
• Chemical factors e.g. tobacco
• Physical factors e.g. ionising/solar radiation
• Viral factors e.g. HPV which is strongly associated with carcinoma in uterine cervix
• Hormonal factors
• Genetics

Question 19

What is the priamary mechanism of what causes cancer?

Answer 19

• Mutations within the genes of cancer cells
• Dysregulated genes within cancer cells

Mechanism is genetic but it is mostly due to somatic mutations not inherited ones

Several mutations are needed for full malignancy

Question 20

How are chemical factors, physical factors and age a risk of cancer?

Answer 20

Age is a risk factor, as one gets older there is increased number of mutations over time, so more likely to get multiple mutations in the same cell

Chemical and Physical are a risk as they cause mutations

Question 21

How hormonal factors a risk for cancer?

Answer 21

They are involved with increased cell turnover (the hormonally driven organ cells are being turned over at a high rate). This high turn over increases the mutation rate

Question 22

Give an example of how genetics can be a risk for cancer

Answer 22

e.g. an defect in DNA repair being inherited