Lecture 2

Question 1

WHAT IS CANCER?

Answer 1

a disease of unregulated growth of cells resulting from genetic mutations

Not a single disease but a generic/umbrella term for a large family of diseases that can affect any part of the body.

Definition: a disease caused by an uncontrolled division of abnormal cells in a part of the body.
* Usually fatal if untreated

Question 2

Cancer cells are abnormal in many ways

Answer 2

• in the way they multiply indefinitely
• how they invade underlying tissue
• migrate to other sites of the body and multiply there

Question 3

Cancer causes death because

Answer 3

the cells proliferate continuously and don’t die at the same rate as normal cells, crowding out healthy cells and causing disruption to normal function

• 2018 – 18 million diagnoses , 9.6 million deaths
• Up to 50% of the population will get cancer at some stage of their life.

Question 4

Neoplastic diseases:

Answer 4

Normal life processes are characterized by continuous growth and maturation of cells, and all cells are subject to control mechanisms that regulate their growth rate.

• In contrast, Neoplasm (Neo =new + plasm=growth) is an overgrowth of cells that serve no useful purpose; for example a tumour

A benign tumour (neuroma) arises from the siatic nerve. Note No infiltration of the adjacent nerve

Question 5

CLASSIFICATION OF TUMOURS
Benign tumor

Answer 5

-small
slow growing
non invasive
well differentiated
stay localized (stay where they are and can’t invade or metastasize)

Question 6

Malignant Tumor

Answer 6

large
fast-growing
invasive
poorly differentiated
metastasize (infiltrate, invade, destroy surrounding tissue and metastasize to other parts of body)

Question 7

Cancers are usually described by

Answer 7

a) the location in the body from which they originated in;
b) the type of cell from which they originate (as many organs are composed of multiple types of tissue)

Question 8

Polyp, papiloma

Answer 8

Any benign tumour projecting from surface epithelium.

Question 9

Adenoma (adeno- gland )

Answer 9

benign tumour of epithelial tissue with glandular origin; often from glandular organs, including the adrenal glands, pituitary
gland, thyroid, prostate

Question 10

Carcinoma

Answer 10

Malignant tumor arising from surface, glandular or parenchymal epithelium (but not endothelium or mesothelium) approx. 90% of human cancers

Question 11

Sarcoma

Answer 11

Malignant tumour of mesenchymal, connective tissue eg bone, cartilage, fat, muscle, vascular, or hematopoietic tissues

Question 12

Leukemia

Answer 12

Neoplasm of blood cells

Question 13

TYPES OF CANCERS
Carcinomas

Answer 13

(cells that cover internal and
external body surfaces)

Question 14

TERATOMA

Answer 14

A tumour of mixed cell components

Often arise in the reproductive tract

May consist of fat, muscle, bone, hair and oil

E.g. Dermoid cyst: A common benign cystic tetratoma that commonly arises in the ovary

Question 15

HALLMARKS OF CANCER

Answer 15

1. Self-sufficiency in growth signals 2. Insensitivity to anti-growth signals 3. Evading apoptosis
2. Limitless replicative potential
3. Sustained angiogenesis
4. Tissue invasion and metastasis

Updated in 2011 to include 2 new Hallmarks
1. Deregulated metabolism
2. Evading the immune system

Question 16

CANCER CELL DIVISION

Answer 16

Normally, cell divisions are strictly controlled. Require signaling from growth factor receptors to proliferate and will undergo a controlled form of cell death (apoptosis) when this signaling ceases or in response to DNA damage

In cancer cells, mutations have removed these controls and allows for the cells to continually grow out of control

– They may not detect neighbouring cells
– They may produce their own growth hormones to stimulate cell division
– They may not produce tumour suppressor proteins
– They ignore normal apoptotic processes

Question 17

GROWTH OF CANCER CELLS

Answer 17

Cancer cells can divide every 2-6 weeks

This is a rough estimate and can vary significantly between different tumor types and different patients

Tumuor size
One million cancer cells = head of a pin One billion cancer cells = a small grape

If cancer cells divide every month, it would be 2.5 years before one cancer cell grows into a small grape-sized tumor.

Question 18

cancer

Answer 18

• a person has usually had cancer for several years before it is detected and/or causes side effects.

Multiple genetic changes required for full development of cancer – can take several years to accumulate

• Often results in gradual changes to the cells structure, shape and biological behaviour
• Often undergoes changes including hyperplasia (increased cell growth) and dysplasia (disorderly growth)
• Development of a small localised tumour called “carcinoma in situ” can then develop. Although not usually dangerous, these in-situ tumours can progress to malignant, aggressive tumours.

Question 19

ONCOGENESIS

Answer 19

Transformation of normal cells into cancer cells is referred to as tumourigenesis, carcinogenesis or oncogenesis

Multi-step process, entailing changes in the expression of many genes. Commonly mutated genes include both tumuour suppressors (genes which work to reduce development of cancer) and oncogenes (genes that promote cancer once mutated)

Question 20

Cancer risk increases with age. Two main theories currently exist to explain this findings

Answer 20

: -Conventional oncogenesis
-Adaptive oncogenesi

Question 21

CONVENTIONAL ONCOGENESIS MODEL - Conventional View :

Answer 21

Aging primarily contributes to increased cancers by facilitating the accumulation of oncogenic mutations (red cells), including activating mutations in oncogenes or genetic/epigenetic inactivation of tumor suppressor genes.

as we age the risk of cancer increases.

More than 80% of human cancers being diagnosed after the age of 50, aging represents the single most important prognostic factor for many cancers, including lung, breast, colon, prostate, and certain leukemias

Question 22

INVASION

Answer 22

When cancer cells spread (no longer benign) from the primary site to another part of the body Complex process involving change of cells to a migratory phenotype and secretion of enzymes to break down surrounding ECM

Question 23

Metastasis

Answer 23

Tumour cells are transported through the circulatory system

Cancer migrate to particular locations within the body including the bone, liver, brain, lungs and lymph nodes, where they may form secondary/tertiary tumours

Most people who die of cancer die of metastatic disease. Prognosis declines significantly the greater the spread of the metastasis

Question 24

TUMOUR ANGIOGENESIS & NECROSIS

Answer 24

As a tumour develops it requires oxygen and nutrients for survival. As a tumour enlarges the centre of the tumour may not receive enough nutrients, forming a necrotic core

Cancers often secrete signaling factors (e.g. VEGF) to induce nearby blood vessels to grow towards them to continue supplying oxygen and nutrients.

This process is known as angiogenesis and can be inhibited with anti-angiogenic therapy to try and limit blood supply to the tumuor

Question 25

Skin cancer

Answer 25

• Usually keratinocyte or melanocyte based tumours
• Often divided into melanoma and non- melonoma

Question 26

Nevus

Answer 26

a benign tumour of melanocytes, often called a mole

Question 27

Melanoma

Answer 27

malignant tumour of melanocytes

Question 28

basal cell carcinoma

Answer 28

Accounts for approximately 75% of all skin cancers.
This highly treatable cancer starts in the basal cell layer of the epidermis (the top layer of skin) and grows very slowly.
Basal cell carcinoma usually appears as a small, shiny bump or nodule on the skin - mainly those areas exposed to the sun, such as the head, neck, arms, hands, and face.
It commonly occurs among persons with light-colored eyes, hair, and complexion.

Question 29

squamous cell carcinom

Answer 29

Accounts for about 20% of all skin cancer cases. Although more aggressive than basal cell carcinoma, this cancer is highly treatable. Squamous cell carcinoma, may appear as nodules or red, scaly patches of skin, and may be found on the face, ears, lips, and mouth. Squamous cell carcinoma can spread to other parts of the body. This type of skin cancer is usually found in fair-skinned people

Question 30

malignant melanoma

Answer 30

-less common, this type of skin cancer is the most deadly,
-79% of all skin cancer deaths

. Malignant melanoma starts in the cells that produce pigment in the skin. Malignant melanoma usually begins as a mole that then turns cancerous
.
This cancer may spread quickly. Malignant melanoma most often appears on fair-skinned men and women, but persons with all skin types may be affected.

Question 31

LUNG CANCER

Answer 31

1 cause of cancer deaths worldwide

• Lung cancers can arise in any part of the lung, but 90% to 95% of cancers of the lung are thought to arise from the epithelial cells, the cells lining the larger and smaller airways (bronchi and bronchioles), for this reason, lung cancers are sometimes called bronchogenic carcinomas.
• Cancers also can arise from the pleura (called mesotheliomas) or rarely from supporting tissues within the lungs, for example, the blood vessels.