Introduction to Cancer Biology

Question 1

What is cancer?

Answer 1

A group of different malignant diseases that will occur:
at different ages.
with different rates of growth, differentiation, abilities to be detected, invasiveness, capacities to spread or metastasize.
with different treatment responses and prognoses

Question 2

What fundamental trait do all types of cancer share?

Answer 2

They are diseases of the genes in that they are the consequence of flaws in the genome of the cancer cell.

Question 3

What genetic alterations that cause cancer are considered caused by “nature”?

Answer 3

Eg. inherited cancer syndromes, immune deficiencies

Question 4

What genetic alterations that cause cancer re considered to be caused by “nurture”?

Answer 4

Poor deit, smoking, etc.

Question 5

What three types of cell damage cause cancer?

Answer 5

Malignant growth is a result of DNA changes, gene transcription or translation.

Question 6

What do the cellular changes that cause cancer lead to?

Answer 6

Leads to transformation of normal cell components into uncontrolled proliferation, spread, and/or metastasis

Question 7

How are tumours identified?

Answer 7

Tumours are identified according to the tissue of origin and whether they are benign or malignant.

Question 8

What is the suffix for benign and malignant tumours?

Answer 8

“oma” (Greek for tumour)

Question 9

What prefixes are given to designate epitehlial origin or mesenchymal origin?

Answer 9

Carcin - epithelial origin

Sarc - mesenchymal

Question 10

What three things does the rate of tissue growth in normal and cancerous tissue depend on?

Answer 10

Duration of the cell cycle
Number of actively dividing cells
Cell loss

Question 11

What is a proto-oncogene?

Answer 11

The genetic portion of DNA that regulates normal cell growth and repair e.g. ras

Question 12

What is a tumour suppressor gene?

Answer 12

The genetic portion of DNA that stops, inhibits or suppresses cell division (this process is disrupted when the gene mutates)

Question 13

What is an oncogene?

Answer 13

Altered for of normal proto-oncogene that may give rise to cancers by interfering with normal cell growth, apoptosis, differentiation.

Question 14

What is the difference between tumour supporessor genes and proto-oncogenes?

Answer 14

Tumour supporessor genes cause cancer when they are inactivated; when a proto-oncogene mutaates into an oncogene then it is activated.

Question 15

What is carcinogenisis?

Answer 15

The process in which normal cells are transformed into cancer cells.

Question 16

What starts the process of carcinogensis?

Answer 16

Starts with a single cell that has genetic changes.

Question 17

What is the stochastic model (Knudson’s random “two hit” model)?

Answer 17

Any cell may be the target of carcinogenesis.

Suggests each cancer cell has the ability to multiply and form new tumours.

Question 18

What is the Cancer Stem Cell model?

Answer 18

Model the most supported by cancer reserachers.

The model states that many different types of cancer cells exist (demonstrating heterogeneity), and with proliferation comes cell division where all the cells have the ability to multiply but only one has the ability to become a new tumour - the cancer stem cell.
Once the tumour is established, the heterogenous cells proliferate and the cancer stem cell enters the G0 (resting) phase of the cell cyl.es

Question 19

What are the three stages of multi-stage theories of carcinogenesis? (3)

Answer 19

Initiation
Promotion
Progression

Question 20

What is the initiaton phase of carinogenesis?

Answer 20

Exposure of a cell to a carcinogen or initiating agent, that makes the cell susceptible to malignant transformation.

Question 21

What are initiating agents?

Answer 21

Initiating agents may be chemical, biological, or physical agents that are capable of causing irreversible changes in cell DNA.

• viral
• environmental
• lifestyle
• genetic factors

Question 22

What is the promotion phase of carcinogenesis?

Answer 22

Promoting agents cause unregulated and accelerated growth in cells that have been previously initiated.
This process can be reversible if the promoting agents are removed early enough (cancer-reversing/cancer-suppressing agents, host characteristics, time/dose limits of exposure).

Question 23

What is a complete carcinogen?

Answer 23

A chemical carcinogen that can initiate and promote malignant transformation.

Question 24

What is the progression phase of carcinogenesis?

Answer 24

At this stage, the cells acquire the malignant characteristics eg. changes in growth rate, invasive ability/potential, angiogenesis.
When a tumour is evident clinically, the differences in individual cells can be detected eg. each cell may grow at a different rate (heterogeneity).

Question 25

What is differentiation?

Answer 25

Differentiation refers to how different the tumour cells are from the cells from which they originated.

Question 26

According to Hanahan, what are the 6 essential alterations in cell physiology that dictate malignant growth?

Answer 26

Evading apoptosis
Self-sufficiency in growth signals
Insensitivity to anti-growth signals
Sustained angiogenesis
Limitless replication potential
Tissue invasion and metastasis

Question 27

How many cancers arise from inhereted genetic mutations?

Answer 27

10%

Question 28

What are the characteristics of genetically predisposed/inherited cancers?

Answer 28

Younger than expected onset of cancer
Multiple generations
Multiple family members
Same or related cancer
Presence of rare cancers and other characteristics

Question 29

What are the clinical implications of genetically predisposed/inherited cancers?

Answer 29

The presence of certain mutated genes can have diagnostic and prognostic value.
Preventing gene mutations is a focus of some chemoprevention clinical trials.
Having an understanding of genetic changes may result in new targeted treatments.
In nursing practice, an understanding of carcinogenesis enhanges care, allows nurses to assist in the translation of information for patients and their families about prevention, health promotion, diagnostics, treatments and follow-up

Question 30

What are two environmental factors that are carcinogenic?

Answer 30

Ionizing radiation

Ultra violet radiation

Question 31

What are some sources of ionizing radiation?

Answer 31

Natural sources and frome xposure to diagnostic/therapeutic sources eg. radiation therapy, x-rays

Question 32

Wat are some sources of ultraviolet radation?

Answer 32

Sun/tanning bed exposure and industrial sources like welding arcs.

Question 33

What are characteristics of chemical carcinogens?

Answer 33

Direct acting do not require activation eg. nitrogen mustard and other antineoplastic drugs (chemotherapy)
Initiators require metabolic activation eg. cigarette smoke

Question 34

What do viral carcinogens do?

Answer 34

Infect DNA and RAN that may lead to the formation of oncogenes and result in cell mutations.

Question 35

What two things might affect someone’s vulnerability to viral carcinogens?

Answer 35

Age and immune function

Question 36

What are some examples of viral carcinogens?

Answer 36

Epstein-Barr herpesvirus (burkitt’s lymphoma, nasopharyngeal cancer)

Human papillomavirus (HPV) - cervical, anal, oropharyngeal cancers

Human herpesvirus 8 (HH8) - Kaposi’s sarcoma

Hepatitis B and C viruses - hepatocellular cancers

HIV - cofactor often due to immunosuppresive properties