14 Non-communicable diseases

Question 1

what is the definition of a non-communicable disease?

Answer 1

a disease which is non-infectious and non-transmissable among people

Question 2

what are the four main types of non-communicable diseases?

Answer 2

cardiovascular

cancer

chronic respiratory diseases

diabetes

Question 3

what is the definition of a risk factor?

Answer 3

a variable associated with an increased chance of developing a disease or infection

Question 4

what are the three ways in which a risk factor can be expressed?

Answer 4

relative risk

fraction of incidences occurring in a group having been exposed to the risk factor

increase in incidence in the exposed group

Question 5

how is the risk calculated?

Answer 5

number of people experiencing event / number of people exposed to risk factor

OR

A = p x (1 + r)^n

where:
A = number of global cases
p = initial number of cases
r = annual increase
n = number of years

Question 6

what are the three main risk factors associated with developing non-communicable diseases?

Answer 6

preexisting conditions

behaviour/lifestyle choices

hereditary/genetic factors

Question 7

give three of the Bradford-Hill criteria for establishing causal relationships

Answer 7

strength

temporality

consistency

theoretical plausibility

coherence

specificity

experimental evidence

Question 8

what are the

• preexisting conditions
• behavioural/lifestyle choices
• hereditary/genetic factors

associated with strokes?

Answer 8

conditions:

• hypertension
• high cholesterol

behaviour:

• excessive salt
• excess alcohol inactivity

hereditary
- sickle cell disease

Question 9

what are the

• preexisting conditions
• behavioural/lifestyle choices
• hereditary/genetic factors

associated with lung cancer?

Answer 9

conditions:

• chronic lung diseases
• radiation exposure

behaviour:

• smoking
• asbestos exposure

hereditary:

• 1st degree family member with lung cancer
• gender

Question 10

what are the

• preexisting conditions
• behavioural/lifestyle choices
• hereditary/genetic factors

associated with asthma?

Answer 10

conditions:
- another allergic condition

behaviour:

• exposure to allergens
• smoking

hereditary:
- blood relative with asthma

Question 11

what are the

• preexisting conditions
• behavioural/lifestyle choices
• hereditary/genetic factors

associated with type 2 diabetes?

Answer 11

conditions:

• aged 45+
• gestational diabetes

behaviour:

• physical activity < 3 times a week
• being overweight

hereditary:

• blood relative with diabetes
• certain ethnicities

Question 12

what is the definition of a tumour?

Answer 12

a lump or growth of abnormal cells that divide uncontrollably

Question 13

what is the definition of cancer?

Answer 13

a disease usually caused by a mutation that causes uncontrolled cell division and the subsequent formation of a tumour

Question 14

what are the four types of cancer?

Answer 14

carcinomas (internal and external body surfaces)

sarcomas (supporting structures)

lymphomas (lymph nodes and immune system)

leukemias (immature blood cells)

Question 15

what is metastasis?

Answer 15

the process in which cancer cells break from the primary tumour and spread to initiate a secondary tumour formation at a different location

Question 16

what is the difference between a benign and malignant tumour?

Answer 16

benign:

• slow growing
• not normally life-threatening
• do not normally grow back

malignant:

• fast growing
• metastatic
• can be life-threatening

Question 17

what is the function of proto-oncogenes?

Answer 17

to stimulate cell division after stimulation from a growth factor

Question 18

how can mutated proto-oncogenes cause cancer?

Answer 18

the base sequence mutates –> oncogenes with different receptor proteins

∴ DNA replication is triggered without the extra-cellular growth factor

Question 19

what is the function of tumour suppressor genes?

Answer 19

to code for proteins that prevent cell division

and initiate breakdown of damaged cells in apoptosis

Question 20

how can mutated tumour suppressor genes cause cancer?

Answer 20

apoptotic stimulation is lost ∴ damaged DNA can be replicated

Question 21

what is a mutagen?

Answer 21

a physical, biological or chemical agent that mutated the DNA of an organism and increases the frequency of mutations above the natural background level

Question 22

give an example of a

• physical
• biological
• chemical

mutagen

Answer 22

physical: ionising radiation
- high energy breaks H bonds in DNA –> change in DNA base sequence
- DNA most susceptible at end of interphase and during mitosis

biological: viruses
- can interfere with p53 production –> prevention of apoptosis

chemical: benzene
- react with and alter structure of DNA
- can be counteracted with anti-oxidant

Question 23

outline the role of the Ras gene and explain [how its mutated form can cause cancer]

Answer 23

division stimulated by extra-cellular messengers

[division stimulated by Ras gene without hormone ∴ cell cycle inhibition removed]

Question 24

outline the role of the c-Myc gene and explain [how its mutated form can cause cancer]

Answer 24

regulator gene on chromosome 8 responsible for regulating 15% of gene expression

[Myc constantly expressed –> unregulated expression of genes –> cell proliferation and cancer formation]

Question 25

outline the role of p53

Answer 25

a transcription factor which plays a role in apoptosis, genomic stability and inhibition of uncontrolled cell division temporarily stops cell cyle at G1/S checkpoint to allow reparation of damaged DNA

Question 26

outline the use of x-rays in detecting cancer give one strength and one weakness of this method

Answer 26

high energy radiation and photographic film plate create a black and white image, depending on the absorbency of the tissues + quick; non-invasive - can't distinguish without further tests

Question 27

outline the use of mammograms in detecting cancer give one strength and one weakness of this method

Answer 27

low energy x-rays of the breast + quick; non-invasive - can't distinguish without further tests

Question 28

outline the use of computerised axial tomography (CAT) scans in detecting cancer give one strength and one weakness of this method

Answer 28

x-ray tube rotates around patient and sends x-rays through their body to a photographic plate which captures a black and white image + non-invasive; produces a 3D image - uses x-rays; can't distinguish without further tests

Question 29

outline the use of ultrasound in detecting cancer give one strength and one weakness of this method

Answer 29

high frequency sound waves are picked up by a handheld transducer and converted to an image by a computer + non-invasive; no x-rays - can't distinguish without further tests

Question 30

outline the use of magnetic resonance imagery (MRI) scans in detecting cancer give one strength and one weakness of this method

Answer 30

creates a magnetic field, which causes protons in H atoms to line up; radio waves then 'spin' the protons - the resulting signal is converted into a 3D image + non-invasive; good for soft tissues - costly; can't distinguish without further tests

Question 31

outline the use of positron emission tomography (PET scans) in detecting cancer give one strength and one weakness of this method

Answer 31

a radioactive tracer (e.g. fluorodeoxyglucose) is injected and used as a marker for glucose uptake; scanner detects gamma radiation given off by the tracer to produce coloured images + accurate; fine detail; 3D coloured images - can't distinguish without further tests

Question 32

outline the use of biopsies in detecting cancer give one strength and one weakness of this method

Answer 32

cell/tissue sample is removed from the body and analysed in a lab for definitive diagnosis + can distinguish - invasive

Question 33

outline the use of blood tests in detecting cancer give one strength and one weakness of this method

Answer 33

diagnosis given concentration of certain compounds in the blood; indication of response to treatment + effective diagnostic tool - invasive

Question 34

what is screening?

Answer 34

testing people who are known to be at risk of a certain condition before symptoms develop

Question 35

what four cancers are routinely screened for in England?

Answer 35

breast bowel cervical prostate

Question 36

who is offered screening?

Answer 36

healthy individuals who have an elevated risk

Question 37

why might a false negative be diagnosed?

Answer 37

cancer doesn't show up on x-ray cancer cannot always be detected immediately cancer can develop rapidly between scans

Question 38

why might a false positive be diagnosed?

Answer 38

after lots of mammograms, the chances of a false positive increases human error (corrected by follow up tests)

Question 39

what are the disadvantages of screening?

Answer 39

distress from false positives unnecessary treatment of benign tumour most are false negatives - targeted screening would be more cost effective

Question 40

what are the two genes most commonly associated with breast cancer?

Answer 40

BRCA1 (c.17) BRCA2 (c.13)

Question 41

name two other genes associated with and describe their effect in causing breast cancer

Answer 41

TP53 + PTEN produce tumour-supressor proteins ∴ mutations in these genes --> DNA damage not properly repaired

Question 42

what is the risk of developing breast cancer?

Answer 42

1 in 8 women (increases with age) ~ 1% risk for BRCA1 male carriers aged 70+

Question 43

why and how do we test for breast cancer?

Answer 43

only if strong family risk required a living relative with breast cancer mutation search (takes weeks/months) i.e. predictive testing

Question 44

what condition makes bowel cancer more likely? what percentage of cases is it associated with?

Answer 44

hereditary non-polyposis colorectal cancer (HNCC) 2-5%

Question 45

what other organs can HNCC increase the chances of cancer in?

Answer 45

uterus urinary system gastrointestinal tract

Question 46

what are the two ways of treating breast cancer by surgery?

Answer 46

lumpectomy - removing the tumour and barrier tissue mastectomy - removing the whole breast and lymph nodes

Question 47

how can colon cancer be treated by surgery?

Answer 47

colectomy - tumorous section removed and colon rejoined by anastomosis

Question 48

what is chemotherapy? what are some potential side effects?

Answer 48

the use of chemicals that are toxic to dividing/cancerous cells - loss of appetite - nausea - increased risk of infection - fatigue (due to low RBC count)

Question 49

what is radiotherapy?

Answer 49

ionising radiation is accurately targeted to destroy actively growing cells

Question 50

what is immunotherapy?

Answer 50

monoclonal antibodies can be tagged with an enzyme that converts an inactive form of a cytotoxic drug into an active form that targets cancerous cells

Question 51

what is hormone therapy in relation to cancer treatment?

Answer 51

oestrogen - stimulates transcription of genetic material if cells have ER+ receptors aromatase inhibitors - can be given to post-menopausal, early-stage breast cancer sufferers LH blockers - prevent oestrogen synthesis