Epidemiology

Question 1

What is the definition of epidemiology?

Answer 1

The study of the distribution and determinants of health-related states or events (including disease),and the application of this study to the control of diseases and other health problems

Question 2

What is cancer epidemiology?

Answer 2

A branch of medicine that studies the patterns of distribution of cancer in humans and the factors that influence the occurrence of different cancers

Question 3

What is rate of disease

Answer 3

Upper part (numerator) is the number of people affected by the problem, event, condition
Lower part (denominator) is the number of persons in the population who are at risk of experiencing the problem, event or condition.
Normally expressed as “X per 100,000 per year
A rate is a fraction

Question 4

What is meant by incidence rate?

Answer 4

The number of new cases, events that occur in a specified time e.g. X per 100,00 per year

Question 5

What is meant by prevalence?

Answer 5

The total number of events or cases, both new and long term, that are present at a particular point in time – expressed as a number as there is no time dimension involved.
•E.g. 25 million people were estimated to be living with cancer in 2005

Question 6

What is mean by survival?

Answer 6

number of persons alive at a specified time period after diagnosis e.g. 1, 5 and 10 year survival figures (disease free )

Question 7

What are morality rates?

Answer 7

The number of deaths divided by the number of individuals in the population (x100, x10,000, x100,000).

Question 8

What are crude death rates?

Answer 8

number of deaths during a given period (normally per 1000 population) – does not take into account differences within the population

Question 9

What are age-specific death rates?

Answer 9

number of deaths in specific age group / number of persons in that age group

Question 10

What is the geographical distribution?

Answer 10

Differences in incidence of the same tumour
Geographical distribution may apply to:
Areas of the world, a particular country, areas within a country

e.g. Breast cancer is more common in western world than third world, but comparatively rare in Japan.

Question 11

How is the distribution of cancer related to age?

Answer 11

Cancer Incidence increases with age
•Peak in children under 5yrs
•Rises more sharply after 35yrs
Different cancers occur more commonly with different age groups
e.g. Leukaemia
• ALL in children v CLL in elderly
e.g. Non-melanoma skin cancer
• Incidence rate increases with increasing age

Question 12

How does gender affect the distribution of cancer?

Answer 12

Some tumours are specific to male or female

Other cancers show a marked difference between sexes e.g. breast cancer

Differences expressed as a ratio e.g. 1:100

Question 13

How do socie-economic groups affect the distribution of cancer?

Answer 13

Higher incidence of breast cancer in higher SE groups

Higher incidence of Head and neck cancer in lower socioeconomic groups

Question 14

How does race and religion affect the distribution of cancer?

Answer 14

High or low incidences seen in various cancers

Cervical cancer - rare in nuns and Jewish women
•Nasopharyngeal cancer - prevalent in Chinese origin
•Liver cancer - increased incidence in black Africans

Question 15

Epidemiology of non-melanoma skin cancer

Answer 15

151, 739 → new cases between 2015 - 2017 in the uk
1115 → deaths in the UK between ‘15 - ‘17
Incidence rates → 166% increase since The 1990s
Peak rate → 90 + years

Question 16

Cancer registration of non-melanoma skin cancers

Answer 16

Cancer registries do not register all primary NMSCs.
•First BCC or SCC per person to standardise comparisons of incidence trends between regions
•First BCC, and all SCCs
•Some NMSCs are not registered - small BCCs treated topically without pathological verification

Question 17

Epidemiology → NMSC

Answer 17

•Most common group of cancers in Europe, Australia and the U.S.A
•20% of all new malignancies and 90% of all skin cancers registered in the UK and Ireland
•BCC ≈75% of NMSCs
•Incidence ↑ with age after 40

Question 18

Epidemiology →cscc

Answer 18

•Squamous cell carcinoma (SCC) is the second most common type of skin cancer and forms approximately 20% of skin cancers and 23% of NMSC (NICE, 2015).
•It occurs more often in men than in women (approximately 2:1 ratio).
•The incidence of cSCC among Caucasians in the UK is