Lecture 3 Flashcards
Cancer mortality and survival (30 cards)
What do we need to define to measure cancer mortality rate?
- a death (the numerator)
- the population (the denominator)
- the time period
What types of death and populations can we have in cancer morality
Death:
1. All-cause deaths
2. Cancer-specific deaths
These two use General population at risk (defined by region, country etc)
- All-cause deaths among
cancer patients - Cancer deaths among cancer patients
These two use Cancer patient population (defined by region, country etc)
How do we work out mortality rate (all cause)?
No. deaths (all causes) in population over time / total person-time at risk (per 1000 person-years)
What are the numbers involved in mortality rate (all causes)
Do = all-cause deaths over time t
Dc = death from cancer over time t
A = Alive at time t
N = population initially at risk
Y = Person-years at risk
How do we work out mortality rate (cancer-specific)?
No. deaths from cancer of interest in population over time / total person-time at risk (per 1000 person-years)
Where can we get this routine data from?
Numerator
Death certification: date, place, & cause of death; sex, age, date of birth, & place of residence
Underlying cause of death numerator of cause-specific mortality rate
Denominator:
Census-based population estimates
Population at mid-point of calendar period of interest x length of period
How to calculate annual mortality rates:
No. deaths from cancer of interest in defined population in 1 year / mid-year population in same year
How was data collected over time (history)
Henry VIII 1518 – required parishes to keep counts of plague deaths temporarily
Beginning in 1538 became standing order, every burial required completion of a document that was the precursor of the modern death certificate. This made the burial legal and allowed the deceased’s estate to be legally disposed of.
Cause of death added but imprecise and inconsistent between parish
1592 – London produced lists of plague resports and put them in Markets / churches
1603 Made formal collating counts and making public throughout England – tabulated counts without personal details
1728 – age was included
It probably started in 17th century London, with this fascinating ‘table of casualties’, compiled in 1662 by a pioneering statistician called John Graunt.His study had the unwieldy title Natural And Political Observations Mentioned In A Following Index And Made Upon The Bills Of Mortality
The Bills of Mortality were weekly lists of deaths in the City of London
Start of demography, estimated London population and rise and fall. Lifetables, sex differences in birth and death
When did cancer appear in mortalilty statistics?
Late 1800s, before it was under gangrene and fistula
When did International Statistical Institute adopt the first international classification of diseases
1893
What did the registration act of 1837 do?
provide provisions to gather more information about deceased populations and various causes of death
What is the purpose of knowing cancer survival?
Measure effectiveness of cancer care and health systems
What components are needed to work out cancer survival?
Case definition = cancer site, sex, stage
Starting point = diagnosis or treatment date
Outcome = Death or other event
How to work out survival probability?
How many died/How many are alive = probability of dying
Probability of survival = 100% - probability of death
How to work out cumulative survivial?
At each year, work out survival probability then times them together over the years
What tools would we use for survival analysis?
Actuarial life tables = probability calculated in intervals. Cumulative survival = product of interval survival
Kaplan-Meier method = survival updated after each event, produces a step curve and can compare groups
What are the three types of survival?
Overall survival = all causes of death
Cancer-specific = only cancer deaths are included
Relative survival = comparing someone with cancer and without cancer in same age, location, year, sex
What is the equation for relative survival? Also called NET SURVIVAL
Observed survival in cancer patients / expected survival in general populations (matched by age, sex etc)
What does cancer incidence reflect?
Cancer causes
What does cancer survival reflect?
Care and treatment
What does cancer mortality reflet?
Overall burden of cancer on the population
In 1981-2009, how did lung cancer mortality change in Sweden and England?
Increased in Sweden and decreased in England
Was the difference in lung cancer due to difference in care?
No, due to changing incidence rates
Which country had the greatest survival gains for lung cancer during 1981-2009?
Sweden
