Lecture 6: Introduction to cancer

Question 1

what does the global burden of disease study show?

Answer 1

• combined male and female data
• shows years of life lost, measures health loss from early death
• provides a measure of the impact of the health conditions
• figure represents leading causes of life loss

Question 2

what does this show?

Answer 2

leading causes of life loss

lung cancer is a leading cause of years of life lost. in 1990 it was ranked 17th, 14th in 2007, 12th in 2017.

Question 3

what this show?

Answer 3

a figure representing burden of DALYs

• shows the leadings causes of DALYs for females
• breast and lung cancer have increased in the rank of DALYs overtime

Question 4

whats this?

Answer 4

DALYs for males

• shows that lung cancer, stomach cancer and liver cancer all contribute significantly to DALYs for males

Question 5

whats this?

Answer 5

number of DALYs by condition group and sex, 2006

cancer is leading cause of health loss estimates

Question 6

what are the most important cancers for male DALYs?

Answer 6

• lung, bowel and prostate cancer are leading cancers for DALYs

Question 7

what are the most important cancers for females DALYs?

Answer 7

• breast, lung and bowel cancer are most important for female DALYs

Question 8

how can the public health model help with cancer?

Answer 8

Epidemiology is only source with scientific evidence of exposure and prevention

Need to know how common a disease is and does it play by the person, place or time.

Identify risk factors and protective factors.

How common/less common is it

Question 9

what is the story about chimney sweeps and scrotal cancer?

Answer 9

• is an example of early cancer investigations.
• Observational descriptive cancer research

found that in england, ~1700s there was an occupational exposure of young boys being chimney sweeps, and it was found that the outcome of this was scrotal cancer!

however, in germany chimney sweeps whore tighter full-body clothing and these boys didn’t have as rates of scrotal cancer as high in england

Question 10

what is the story about this cancer?

Answer 10

a doctor found many cases of kids with tumours in their jaws… it was often associated with another tumour somewhere in their body

• it was described as an ‘unknown lymphoma
• incidence was 18 per 100,000 children per year
• occurance was 6 months to 14 years- peak at 5-6 years
• more common in boys
• it was later discovered that it was not a new cancer, but a form of epstein bar virus - burkitt’s lymphoma
• was common in africa

Question 11

what this show?

Answer 11

increase in lung and bronchus cancers in 1930-1990, but started to decrease after 1990.

• likely due to increased smoking rates in males during war times

Question 12

what this shows?

Answer 12

females didn’t have us much of an increased death by lung and bronchus cancer as males.

the increase also took place from mid 1960s to 1990s+

• this is likely to be because females took up smoking a lot later than males did

Question 13

why are case control studies better for cancers?

Answer 13

• cancers are rare outcomes
• RCTs wouldnt be ethical
• long periods between exposure and outcome
• would need to follow people up for long periods of time
• not efficient

Question 14

what is an example of a case-control study for cancer?

Answer 14

‘Smoking and carcinoma of the lung”

published in the british medical journal, 1950

Question 15

what is an example of a cohort study for cancer?

Answer 15

“the mortality of the doctors in relation to their smoking habits”

• published in britsih medical journal, 1954

Question 16

what is cancer?

Answer 16

unregulated proliferation of cells

a breakdown in the processes which controls cell proliferation, differentiation, death of cells

Question 17

how do you defince cancer growth and invasion?

Answer 17

• cancer is a term used for diseases in which abnormal cells divide without control and are able to invade other tissues
• cancer cells can spread to other parts of the body through the blood and lymph systems. it can also spread across potential spaces in the body
• cancer is not just one disease but many diseases. there are more than 100 different types of cancer
• most cancers are named for the organ or type of cell which they start in

Question 18

what is the progression of cancer?

Answer 18

most solid tumours arise in areas of hyperplasia

1) hyperplasia: increased local tissue size due to abnormal cellular proliferation
2) dysplasia: abnormal cell architecture
3) carcinoma in-situ: very abnormal cells, like cancer
4) invasion: abnormal cells invade the underlying tissue
5) metastisis: migration of cancer cells from the primary tumour to distant sites in the body, and development of secondary tumours at those sites

Question 19

what are the cancer types?

Answer 19

• carcinoma
• sarcoma
• leukaemia
• lymphoma and myeloma
• CNS cancers
• benign tumours (not cancerous)
• malignant tumours (cancerous)

Question 20

what are some key things to consider about the development of cancer?

Answer 20

• inherited predisposition of <5% of all cancers
• epigenetic mechanisms and direct DNA damage occurring as a result of environmental exposures are responsible for the development of the great majority of cancer
• usually a long time from exposure to cancer developing
• can be 15-40 years
• cancer is usually a rare complication of a common exposure

Question 21

what are common causes of cancer?

Answer 21

• genes
• environmentsl
• chemical
• infectious agents
• lifestyle (diet, physical activity, body)
• occupation

Question 22

what is primary prevention?

Answer 22

aims to prevent disease from ocurring, to reduce incidence

Question 23

what is secondary prevention?

Answer 23

aims to improve outcomes in people who have developed disease, to reduce morbidity and mortality

Question 24

what is teritary prevention?

Answer 24

aims to reduce number or impact of complications of disease

Question 25

what is screening?

Answer 25

• aims to improve outcome, usually to reduce mortality
• there are screening programmes vs opportunistic screening
• all screening programmes do harm, some can do good as well
• screening is a pathway, not a test!

Question 26

what is the screening pathway?

Answer 26

Question 27

what is the criteria for assessing screening programmes?

Answer 27

1. the condition is suitable for screening
2. there is a suitable test
3. there is an effective and accessible treatment or intervention for the condition identified through early detection
4. there is high quality evidence, ideally from randomised controlled trials, that a screening programme is effective in reducing mortality or morbidity
5. the potential benefit from the screening programme should outweigh the potential physical and psychological harm (caused by the test, diagnostic procedures and treatment)
6. the health care system will be capable of supporting all necessary elements of the screening pathway, including diagnosis, follow up and programme evaluation
7. there is consideration of social and ethical issues
8. there is consideration of cost-benefit issues

Question 28

what are some NZ national screening programmes?

Answer 28

• breastscreen aotearoa
• national cervial screening programme
• national bowel screening programme

Question 29

what are DALYs?

Answer 29

DALY is made up of the sum of the years of life lost due to premature mortality + years of healthy life loss due to disability