28) Treatment of Cancer

Question 1

1) Cancer definition

Answer 1

disease in which control of growth is lost in one or more cells leading to solid mass of cells known as a tumour

growing (primary) tumour often becomes life-threatening by obstructing vessels and/or organs

death most often caused by spread of primary tumour to one or more other sites in the body (i.e metastasis) making surgical intervention impossible

other types of cancers such as leukaemias involve a build up of white blood cells in the blood

Question 2

2) Naming of cancers

Answer 2

in relation to the type of tissue they arise from

Question 3

3) Tumour definition

Answer 3

also called a neoplasm

an abnormal tissue mass or growth which results from neoplasia

neoplasia is a state in which control mechanisms governing cell growth become deficient leading to cell proliferation

Question 4

4) Sarcoma definition

Answer 4

tumours occurring in mesodermal tissue which includes connective tissue, bone and msucle

Question 5

5) Osteosarcoma definition

Answer 5

bone cancer

Question 6

6) Carcinoma definition

Answer 6

tumours of the epithelial cell tissues such as mucous membranes and glands (including cancers of the breast, ovary and lung)

Question 7

7) Blastoma definition

Answer 7

cancers of the blood or haemopoietic tissue

these can involve lymphoid, erythroid or myeloid cells which generally fall into the sarcoma category

Question 8

8) Leukaemias definition

Answer 8

originate in leukocytes and may be myeloid, lymphatic or monocytic

in addition these particular cancer types may be described as chronic or acute

Question 9

9) Myelomas definition

Answer 9

refer to bone marrow cell tumours

in multiple myeloma a clone of plasma cells is involved

Question 10

10) Primary polycythaemia definition

Answer 10

neoplasia of erythroid cells

Question 11

11) Lymphosarcoma definition

Answer 11

cancer of lymphoid cells

Question 12

12) Hodgkin’s disease definition

Answer 12

example of a lymph adenoma

Question 13

13) Histology of cancer cells

Answer 13

irregular nuclear border

nucleus that engrosses most of the cell

Question 14

14) Growth pattern of tumour cells

Answer 14

in early stages of tumour growth, cancer cells look like the original cells from which they derive

later lose appearance and function of these tissues

requires only a slow increase in the rate of proliferation to gradually outgrow normally controlled cellular populations

Question 15

15) Stages involved in the formation and progression of solid tumours

Answer 15

transformation of normal cell into cancer cell (primary tumour)

metastasis-cells break off and move around body

cancer cell- grows into secondary tumour

Question 16

16) Metastases definition

Answer 16

ability of solid tumours to spread to new sites in the body thus establishing secondary cancerous growths

tumour cells may easily penetrate the walls of lymphatic vessels and distribute tot eh draining lymph nodes and hence move to distant sites

can also invade blood vessels directly since capillaries have weak thin walls that offer little resistance

may also spread across body cavities from one organ to another, e.g ovary to stomach

most patients die of cancer due to metastatic spread to vital organs

both primary and secondary tumours not only expand in size but also infiltrate surrounding tissue

when nerve endings are affected then pain and discomfort is experienced

Question 17

17) Importance of early diagnosis in cancer

Answer 17

at point of diagnosis, curative surgical or radiological treatment only possible if metastasis of primary tumour has not occurred

early diagnosis essential as about 50% of malignant tumours have already metastasised prior to diagnosis so the condition is often beyond reach of curative surgery or radiotherapy alone

in these cases systemic chemotherapy can reduce risk of further formation and growth of secondary tumours

Question 18

18) Screening of cancer

Answer 18

highly sensitive analytical techniques to detect tumour markers (e.g. proteins or glycoproteins) in easily obtain body fluids such as blood, urine and saliva and are likely to revolutionise early diagnosis

Question 19

19) Possible causes of cancer

Answer 19

exposure to ever increasing number of chemicals (carcinogens) in the environment

diet may also be significant contributing factor

occupation factors, life-style and diet

genetic predisposition is also a factor in some types of disease

Question 20

20) Challenges of treating cancer

Answer 20

more than 200 different diseases

late diagnosis

metastasis

tumour cells evolve to become more aggressive and therefore very similar to healthy cells

most drug targets are also present in healthy cells (unlike bacterial cells)

Question 21

21) Hallmarks of cancer

Answer 21

small number of molecular, biochemical and cellular traits shared by most and perhaps all types of human cancers

Question 22

22) Rareness of cancer cells during human lifetime

Answer 22

multiplicity of defences

Question 23

23) Characteristic hallmarks of tumour cancer cells

Answer 23

evading growth suppressors

avoiding immune destruction

enabling replicative immortality

tumour promoting inflammation

activating invasion and metastases

inducing angiogenesis

genome instability and mutation

resisting cell death

deregulating cellular energetics

sustaining proliferative signalling

Question 24

24) Mechanisms of genomic damage

Answer 24

internal factors

external factors

hereditary factors

Question 25

25) Internal factors of genomic damage

Answer 25

tumour formation results from changes to DNA sequence brought about by malfunction of normal DNA processing systems within the cell

addition or loss of genetic material during normal DNA processes such as repair, DNA bases may be added or deleted, which can have a similar effect to a point mutation as it can alter the codon reading frame and lead to production of faulty proteins, critical for control of cell growth

changed gene expression, such as uncontrolled expression or amplification

if growth factors or proteins responsible for receptor formation are involved- then tumourogenesis may result

Question 26

26) Point mutation

Answer 26

only one base is altered (i.e a frame-shift mutation)

resulting a new codon can cause insertion of an incorrect amino acid into the corresponding position of the protein

should the protein be critical for proliferation, then tumourogenesis may result

Question 27

27) Translocation mutation

Answer 27

entire segment of DNA may be moved from one part of the gene or chromosome to another

in this case, loss of the proteins corresponding to the original DNA sequences or the production of a new protein corresponding to the novel fusion sequence may lead to tumourogenesis

Question 28

28) Hereditary factors known to contribute to genomic damage

Answer 28

number of genes identified that predispose individuals to certain types of cancer
e.g. BRCA1 and BRCA2 are associated with breast cancer

led to the introduction of diagnostic screening with subsequent genetic counselling for affected individuals

Question 29

29) Carcinogens in environment and food known to cause genomic damage

Answer 29

certain chemicals in environment and some encountered in diet, lifestyle and occupation can lead to tumourogenesis

Question 30

30) Examples of occupational carcinogens

Answer 30

tarry deposits from coal fires known to cause scrotal skin cancer

vinyl chloride used by workers in the plastics industry have been associated with angiosarcoma of the liver

furniture industry workers prone to nasopharyngeal malignancies induced by inhalation of small particles

many of these organic carcinogens work by covalently modifying DNA (either before or after metabolism)

Question 31

31) Asbestos as a cause of cancer

Answer 31

causes pleural and peritoneal tumours

due to physical damage of chromosomes by microscopic fibres of asbestos which are needle like and can penetrate the cellular and nuclear membranes

Question 32

32) Lifestyle factors that affect the growth of cancer

Answer 32

tobacco

alcohol

other recreational drugs

obesity

exercise

Question 33

33) How human T-cell leukaemia virus (HTLV-1) causes cancer

Answer 33

results in overexpression of interleukin 2 by introducing gene known as tax

leads to adult T-cell lymphomas with an increase in the number of lymphocytes

Question 34

34) How Epstein-Barr virus (EBV) causes cancer

Answer 34

causes Burkitt’s lymphoma which allows infected lymphocytes to become immortal

Question 35

35) How Hepatitis B virus causes cancer

Answer 35

linked to hepatocellular carcinoma

X-gene in HBV codes for proteins that promote transcription

Question 36

36) How Human Papilloma virus causes cancer

Answer 36

over 50 different types

linked to cervical cancer

virus produces several proteins some of which enhance mitosis whilst others interfere with P53 (a tumour suppressor gene) or modify the interaction between cellular proteins and transcription factors

Question 37

37) How bacterial infections cause cancer

Answer 37

bacterial infections can lead to tumourogenesis and stomach cancer e.g. Helicobacter pylori colonises stomach and is associated with the development of stomach ulcers

Question 38

38) How worm infections are known to cause cancer

Answer 38

certain parasitic worms are known to be carcinogenic

clonorchis sinensis and opisthorchis have been associated with cholangiocarcinoma

schistosoma species associated with malignant bladder cancer

Question 39

39) How radiation causes cancer

Answer 39

malignancies linked to exposure to a or B particles or gamma or X-rays which are known to damage DNA fragmentation through formation of free radicals

Question 40

40) How radon gas is known to cause cancer

Answer 40

naturally occurring radioactive gas that once inhaled, enters the bloodstream and delivers radiation to all tissues

bone marrow is particularly sensitive and so leukaemias predominate