Epidemiology: Definitions, Incidence Rates, and Diagnoses

Epidemiology

RADT111 24/25
Chris Corcoran & Jenny CallenderENGLAND (1086)
KINGDOM OF MANN
(NORWAY)
SCOTLAND

Definition for Epidemiology

DURESME
IRELAND
Nort Treding
Epidemiology - 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
Lindesie
CESTRESCIRE
SNOTINGHAMSCIRE
DERBYSCIRE
Chersteuen
It examines epidemic and endemic diseases.
TROPE
CIRI
DECESTRESCIRE
Roceland
NORFULC

• Epidemic - a widespread occurrence of an infectious disease in a community at a
  particular time
• Endemic - the distribution in a particular population

HEREFORDSCIRE
EDEFORDSCIRE
HERFORDSCIRE
EXSESSA
BERROCHESCIRE
WILTESCIRE
SUDRIE
CHENTH
SUMERSETE
HANTESCIRE
SUDSEXE
DEVENSCIRE
DORSETE
"to promote, protect and restore good health"
FRANCE
DUCHY OF
NORMANDY
LINCOLESCIRE
Holland
SUDFULC
MIDELSEXE
IMEAttempts to determine .....

• " Who is prone to a particular disease
• " Where there may be a higher risk
• " When the disease is most likely to occur
  If there are changing trends over time
• " What common exposures victims have in common
• " How much does that exposure increase risk
• " How many cases of the disease could be avoided by removing the exposure

Cancer Epidemiology

A branch of medicine that studies the patterns of distribution of cancer
in humans and the factors that influence the occurrence of different
cancers
Related to environmental and personal characteristics that vary by
place, time and subgroup of population.
POPULATION

History of Epidemiology & Cancer

XXXI
BERI
L
A
SILVIY
RDINUS
DOCTOR
RAMAZZINUS
DICIN
PROF
1713, Bernardino Ramazzini, reported the
virtual absence of cervical cancer and
relatively high incidence of breast cancer in
nuns and wondered if this was in some way
related to their celibate lifestyle.
An important step toward understanding
the importance of hormones and sexually-
transmitted infections and cancer risk.
0
John Snow
John Snow observed where the cases of
Cholera occurred in 1854 in London's Soho
district
1775, Percival Pott of Saint
Bartholomew's Hospital in London
described an occupational cancer
in chimney sweeps, cancer of the
scrotum, which was caused by soot
collecting in the skin folds of the
scrotum.

Epidemiology: Rate of Disease

Basis of all epidemiology is the comparison of groups of people
A rate is a fraction
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
100

Epidemiology: Incidence and Prevalence

Incidence (or incidence rate)

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

Prevalence

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

Survival Rates

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

• Female survival (%)
  Male surival (%)
  Persons survival (%)
  100
  80
  Net survival (%)
  60
  I
  I
  T
  40
  20
  I
  I
  T
  0
  one
  five
  ten

Breast cancer

• Female survival (%)
  100
  80
  I
  Net survival (%)
  60
  40
  20
  0
  one
  five
  ten
  Years after diagnosis
  I
  I
  Years after diagnosis
  H

Mortality Rates

Mortality rate: The number of deaths
divided by the number of individuals in
the population (x100, x10,000, x100,000).
Crude death rate: number of deaths
during a given period (normally per 1000
population) - does not take into account
differences within the population
Age-specific death rate: number of deaths
in specific age group / number of persons
in that age group
Deaths
Deaths from breast
cancer, 2015-2017,
UK.
Percentage of all deaths
7%
Percentage breast
cancer contributes to
total cancer deaths,
2015-2017, UK
Age
-39%
Change in breast
cancer mortality rates
since the early
1970s, UK
Male Deaths
-
Male Rates
14
4.2
Average Number of Deaths per Year
12
3.6
10
3.0
8
2.4
6
1.8
4
1.2
Mortality Rate per 100,000
2
0.6
0
0.0
0 to 05 to 10 to 15 to 20 to 25 to 30 to 35 to 40 to 45 to 50 to 55 to 60 to 65 to 70 to 75 to 80 to 85 to 90+
04 09 14 19 24 29 34 39 44 49
54
59 64 69 74 79
84 89
Age at Death
Trend over time
11,399
90+
years
Peak mortality rate
for breast cancer,
2015-2017, UK

Epidemiology and Prevention of Cancer

Principal role of epidemiological studies in oncology has been in the
prevention of cancer.
Played a major role in establishing occupational hazards in several
industries (e.g. bladder cancer in aniline dye workers)
The link between smoking and lung cancer

Distribution of Cancer

5 Key Criteria for Distribution of Cancer

Geography
Race and/or
religion
Age
Socio-economic
groups
Gender

Distribution of Cancer: Geography

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.

Distribution of Cancer: Age

Cancer Incidence increases with age
Peak in children under 5yrs
0
Rises more sharply after 35yrs
Different cancers occur more commonly with different
age groups
e.g. Leukaemia
0
ALL in children v CLL in elderly
e.g. Non-melanoma skin cancer
0
Incidence rate increases with increasing age

Distribution of Cancer: Gender

Some tumours are specific to male
or female
Bladder
Bladder
Urethra
Penis
Seminal
vesicle
Urethra
·Prostate
Rectum
Cancerous
tumor
Prostate
Scrotum
Fundus
Fallopian tube
Lumen (cavity) of uterus
Fimbriae
Infundibulum
Ovary
Ovarian ligament
Endometrium
Myometrium
Cervical canal
Cervix
Vagina
Other cancers show a marked
difference between sexes e.g.
breast cancer
Differences expressed as a ratio e.g.
1:100

Distribution of Cancer: Socio-economic Groups

Higher incidence of breast cancer in higher SE groups
Higher incidence of Head and neck cancer in lower socioeconomic groups

Distribution of Cancer: Race and Religion

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
  t

Epidemiology of Non-melanoma Skin Cancer

Epidemiology - 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.

Non-melanoma Skin Cancer Cases

Cases
151,739
New cases of non-
melanoma skin
cancer, 2015-2017,
UK
Deaths
1,115
90+
years
Deaths from non-
melanoma skin
cancer, 2015-2017,
UK
Peak rate of non-
melanoma skin
cases, 2015-2017,
UK
+166%
Change in non-
melanoma skin
cancer incidence
rates since the early
1990s, UK
Cancer Research UK: Professional cancer statisticsNote:
Statistics on non-
melanoma skin cancer are
an estimate!
Because non-melanoma skin cancers are easy to treat and cure, they're often left
out of national cancer statistics.

Cancer Registration (Non-melanoma)

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
  Public Health England: National Cancer Registration and Analysis Service

Epidemiology - NMSC

• 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 1 with age after 40

Epidemiology: cSCC

• 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 increasing.
• The incidence 1 with age.
  As with BCC, SCC is under-reported and statistics for SCC and BCC are often grouped together.

Age-Standardised Incidence Rate of Basal Cell Carcinoma

Age-standardised incidence rate (per 100,000 population) of basal cell
carcinoma in different cancer registries, 2000-2002 and 2008-2010
180
Age-standardised incidence rate
(per 100,000 population)
160
140
120
100
80
=Males - 2000-2002
60
40
=Females - 2000-2002
20
0
=Males - 2008-2010
=Females - 2008-2010
ECRIC
NWCIS
NYCRIS
OCIU
SWCIS
ThamesCR
TrentCR
WMCIU
Scotland
Northern Ireland
Ireland
Cancer Registry
Source: Celtic-NCDR 2010; ISD Scotland; NCR Ireland; * Thames CR did not register BCCs in 2000-2002
(Error bars represent 95% confidence intervals)
Incidence rates for non-melanoma skin cancer in the UK are highest in people aged 90+ (2013-2015).

Age-Standardised Incidence Rate of Squamous Cell Carcinoma

Age-standardised incidence rate (per 100,000 population) of squamous cell
carcinoma in different cancer registries, 2000-2002 and 2008-2010
80
H
Age-standardised incidence rate
(per 100,000 population)
70
T
T
T
T
40
T
I
I
I
T
20
Females - 2000-2002
10
Males - 2008-2010
Females - 2008-2010
ECRIC
NWCIS
NYCRIS
OCIU
SWCIS
ThamesCR
TrentCR
WMCIU
Scotland
Northern Ireland
Ireland
Cancer Registry
(Error bars represent 95% confidence intervals)
60
50
Males - 2000-2002
30

Percentage of New NMSC Diagnoses by Age and Sex

Figure 4: Percentage of new NMSC diagnoses at
different age groups (years), by sex, England, 2010
15%
20%
85+
75-84
32%
27%
65-74
55-64
28%
24%
45-54
35-44
15%
25-34
0
9%
4%
10-24
Males
Females
Source: NCDR
Females in the UK, non-melanoma
skin cancer accounted for around
65,400 new cancer cases in 2017.
Males in the UK, non-melanoma
skin cancer accounted for around
86,100 new cancer cases in 2017
15%

Percentage of Treated NMSCs by Anatomical Location and Sex

Figure 3: Percentage of treated NMSCs at different
anatomical locations, by sex, England, 2011

• Head and
  Neck
  Upper Limbs
  73%
  78%
  Trunk
  Lower Limbs
  6%
  7%
  8%
  10%
  13%
  4%
  Overlapping /
  Unspecified
  Males
  Females
  Source: Inpatient HES

Registered Incidence of Skin Cancer in England, 2006

Registered Incidence of Skin Cancer in England, 2006
Age Standardised Incidence Rate Per 100,000 Population
140
120
100
80
60
40
20
0 -
EAST MIDLANDS
EAST OF ENGLAND
LONDON
NORTH EAST
NORTH WEST
SOUTH CENTRAL
SOUTH EAST COAST
SOUTH WEST
WEST MIDLANDS
YORKSHIRE & THE HUMBER
ENGLAND
Strategic Health Authority
Basal Cell Carcinoma Squamous Cell Carcinoma Malignant Melanoma

Mortality from Skin Cancer in England, 2006

Mortality from Skin Cancer in England, 2006
4
Age standardised mortality rate per 100,000 population
3.5
3
2.5
2
1.5
1
0.5
0 -
EAST MIDLANDS
EAST OF ENGLAND
LONDON
NORTH EAST
NORTH WEST
SOUTH CENTRAL
SOUTH EAST COAST
SOUTH WEST
WEST MIDLANDS
YORKSHIRE &THE HUMBER
ENGLAND
Strategic Health Authority
Non Melanoma Skin Cancer Maligant Melanoma