1. Why screen for cancer?

2.  Burden of Cancer
Cancer Registry
Cancer Incidence
Cancer Mortality
Cancer Prevalence
 Screening for Cancer

3. Incidence
• Number of new cases diagnosed with a
disease (e.g. cancer) in a defined
population over a given period of time.
• Usually expressed as a rate e.g. per
100,000.

4. Benefits Cancer Incidence vs Mortality
Incidence
 Counts cancers which are cured eg
skins
 Event closer to risk factors especially if
long survival
 Allows levels to be monitored
irrespective of treatment changes
 Allows calculation of survival
 Data cleaned more than deaths

5. Non-melanoma skin
25%
Trachea, Bronchus &
Lung
13%
Prostate
11%Colon
7%
Rectum
4%
Stomach
4%
Bladder
3%
NHL
3%
Kidney
2%
Others
28%
Most Common Cancers (Males)
Lung
24%
Stomach
4%
Other
25%
Leukaemia
3%
NHL
3%
Kidney
3%
Bladder
4%
Pancreas
4%
Oesophagus
6%
Colorectal
11%
Prostate
13%
Cancer deaths, males, UK,
2004
Cancer incidence, males, UK,
2004

6. Ovary
4%
Trachea, Bronchus &
Lung 8%
Breast
21%
Non-melanoma skin
26%
Others
22%
Rectum
3%
Colon
7%
NHL
3%
Uterus
3%
Malignant Melanoma
3%
Cancer incidence, females, UK,
2004
Most common Cancers (Females)
Colorectal
10%
Ovary
6%
Oesophagus
3%
Stomach
3%
Bladder
2%
Leukaemia
3%
NHL
3%
Pancreas
5%
Breast
17%
Lung
18%
Other
29%
Cancer deaths, females, UK,
2004

7. Incidence Trends

8. Cancer Deaths

9. Mortality Trends

10. Prevalence
• Total number of cases (old and new) with a
disease (e.g. cancer) in a defined population
within a given period of time.
• Point prevalence – at a specific point in time
• Period prevalence – over a defined time period
• Usually expressed as a proportion/percentage.

11. Cancer Prevalence
26
1444
2544
377 470 490 475 453
280 225 204 289 152 119 96 36 33
4186 1291
601 489 358
188
609
150
510
199 167 115
296
114 78 91 38 20
0
500
1000
1500
2000
2500
3000
3500
4000
4500 Breast
Colorectal
Prostate
Melanoma
Lymphoma
Lung
HeadandNeck
Uterus
Bladder
Ovary
Kidney
Leukaemia
Stomach
Cervix
Testis
Multiple…
Oesophagus
Brain
Pancreas
Liver
Cancer site
Prevalenceof cancer in Northern Ireland: Diagnosedin 2000-2004, alive at the end of 2004
Female
Male

12. Mortality/Survival
 Mortality rate: number of deaths caused by
disease in a population over a specified
time period. Usually expressed per 1000
or per 100,000 per year.
 Survival rate: percentage of people within
a specified population who are alive for a
specified time period after diagnosis.
Usually expressed as a five-year relative
survival rate.

13. Survival
Figure. 3.22: Age-Standardised relative survival for breast cancer by stage

14. Survival
Figure. 3.22: Age-Standardised relative survival for prostate cancer by stage

15. Survival
Figure. 3.22: Age-Standardised relative survival for colorectal cancer by stage

16. Survival
Figure. 3.22: Age-Standardised relative survival for lung cancer by stage

17. Screening - scrutiny of people in
order to detect the presence of
disease, disability or other
attributable under study.
Rationale - Early diagnosis leads
to more effective treatment and a
greater cure rate.

18. Types of Screening
Type A Screening to detect early stage or
asymptomatic disease - e.g.
Mammogram.
Type B Screening detects a precancerous
statee.g. cervical cancer.

19. Screening Test
 Cheap, quick, acceptable.
 Reliable (same result if repeated).
 Validity (how good is test at
discriminating who has the disease from
those who do not). Measured using
Sensitivity and Specificity.

20. Trends in Cervical Cancer Mortality

22. http://www.qub.ac.uk/research-centres/nicr/FileStore/PDF/Filetoupload,176739,en.pdf

23. What cancers do we screen for?
 Breast Cancer
 Cervical Cancer
 Colorectal cancer
 No screening – ovary marker CA125
-- liver markers afp,CA125,
-- prostate marker PSA

24. Negative Effects of Screening
 Hazards from screening test, e.g. Radiation.
 Reliance on false negatives so ignoring symptoms.
 Anxiety and additional tests for false positives.
 Opportunity Costs.
 Creating ‘patients’ from well people.
 Anxiety and interventions in those whom disease will never
kill.
 Risk from interventions.
 Anxiety in those who choose to ignore invitation.
 Over diagnosis.

25. World age-standardised incidence and
mortality rates for prostate cancer for
selected countries, estimates for the year 2000