20 - Oncology Basics Part 1

Question 1

What are proto-oncogenes ?

Answer 1

• Normal cellular genes that are important regulators of normal cellular processes
• Mutations that alter their expression can activate them to act as oncogenes (tumor-inducing)

Question 2

What are tumor suppressor genes?

Answer 2

• Suppress growth of tumors

- Mutations render them inactive allowing tumors to develop

Question 3

What is the immune system’s response?

Answer 3

to reject or destroy cells perceived as non-self

Question 4

Describe immunologic surveillance

Answer 4

• Lymphocytes continually check cell surfaces, detect and destroy cells with abnormalities
• Involves cytotoxic T-cell natural killer cells, macrophages, and B lymphocytes
• Some cancer cells have changes on their surface antigens (Tumor-associated antigens)

Question 5

What are some escape mechanisms by which cancer cells evade immune system ?

Answer 5

• Suppression of factors that stimulate T-cells
• Weak surface antigens allow cancer cells to “sneak through” surveillance
• Development of tolerance of immune system
• Suppression of immune response to products secreted by cancer cells
• Induction of suppressor T-cells
• Blocking antibodies that bind TAAs (tumor associated antigens)

Question 6

Describe altered cell growth

Answer 6

• “Immortality”: unlimited number of cell divisions
• growth without “go” signals
• growth factors, cell-to-cell adhesion molecules, extracellular matrix components
• ignoring “stop” signals
• loss of contact inhibition: invade neighbouring cells, keep dividing
• loss of cell cycle control
• avoidance of APOPTOSIS

Question 7

Body cells are not immortal and can only divide a limited number of times due to _____

Answer 7

telomeres

Question 8

What are telomeres?

Answer 8

repeated DNA sequence and protective caps on each chromosome and are held in place and maintained by enzyme telomerase

Question 9

Telomeres become smaller and smaller with each cell ___

Answer 9

division

Question 10

______ is increased in cancer

Answer 10

telomerase

Question 11

Process of Tissue Invasion & Metastasis

Answer 11

Getting into the bloodstream: altered adhesion and mobility

Surviving in the bloodstream: altered anchorage-dependent growth

Getting back into tissue: extravasation and attraction to adhesion molecules in metastatic site

Angiogenesis is important component

Question 12

What is angiogenesis ?

Answer 12

Tumor needs a blood supply for it to grow.. Will send out growth factors (ex. VEGF) to get blood supply

Question 13

What can cause cancer?

Answer 13

1) External stimuli causing genetic mutation:
-Carcinogens:
Chemicals: tobacco smoke, arsenic, EtOH, vinyl chloride, benzene
Diet

2) Exposure to viruses

3) Genetic abnormalities (inherited/heritable)
- Oncogenes, porto-oncogenes, tumor suppressor genes
- Inherited genetic risk: 5-10% of cancers

4) Chromosomal abnormalities (spontaneous)
- Increased #, deletion, translocation, breakage

5) Immune system abnormalities

Question 14

Most common virus that can cause cancer?

Answer 14

Hep B - liver cancer

Question 15

What are some inheritable genetic mutations?

Answer 15

• BRCA-1: breast, ovarian, prostate
• BRCA-2: breast
• RB1: retinoblastoma
• WT1: Wilm’s tumor
• Li Fraumeni (p53 supressor mutation): breast, brain, acute leukaemia, soft tissue sarcomas, osteosarcomas, adrenal cortical carcinoma
• Hereditary non-polyposis colorectal cancer
• Familial adenomatous polyposis
• MEN1 & MEN2: multiple Endocrine Neoplasia

Question 16

Up to 80% of cancers could be prevented if Canadians made healthier choices about ?

Answer 16

• tobacco
• diet
• exercise
• sexual practices (HPV, Hep B/C, etc)

Question 17

What are some early warning signs for common cancers that should be acted upon ?

Answer 17

• Change in bowel or bladder habits
• Sores that will not heal
• Unusual bleeding or discharge
• Thickening or lump in breast or elsewhere
• Indigestion or difficulty swallowing
• Obvious change in a mole or wart
• Nagging cough or hoarseness

Question 18

Describe what a histopathology looks like

Answer 18

What it looks like under the microscope

• Tissue of origin
• Tumor grade: how aggressive is it?
• Receptors, chromosomal abnormalities, tumor markers, etc.

Question 19

Disease stage ?

Answer 19

how far has it spread?

Question 20

What is a carcinoma ?

Answer 20

• epithelial tissue
• adeno-glandular/columnar
• squamous - squamous

Question 21

What is a sarcoma ?

Answer 21

• connective tissue
• osteo-bone
• blastoma - embryonal origin

Question 22

What is a teratoma ?

Answer 22

germ cells

Question 23

What is a hematologic cancer?

Answer 23

leukemia, lymphoma

Question 24

metastatic

Answer 24

means it’s spread

Question 25

Describe the clinical staging of cancer (0-4)

Answer 25

0: cancer in situ
1: tumor limited to tissue of origin
2: limited local spread
3: extensive local and regional spread
4: metastasis (spread)

Question 26

Describe the TNM Classification of cancer

Answer 26

One example of a classification system - there are MANY staging systems that are disease-specific

T = Tumor size
N = Spread to Lymph nodes
M = Metastasis