Sunday, September 20, 2009
Cancer: The facts
About our cancer statistics
The statistics reproduced in our guides to common forms of cancer come from Cancer Research UK and the NHS, via the Office for National Statistics.
The most recent year for which a full set of statistical data is available is 2005.
This is for various reasons, primarily the natural delay in producing an accurate, full set of data concerning cancer, and also the complexities involved in collating data collected across different parts of the United Kingdom, which publish data at different times.
There are a number of points to bear in mind when studying the data.
Our graphics make broad comparisons between the number of cases for a specific cancer in a given year, and the number of deaths which resulted from the same cancer in the same year.
It is important to note that these two sets of figures are not always directly related.
For example, the figure for deaths includes all those from the named cancer in a given year, not just those from cases reported in that same year.
So some patients with a given cancer may have first reported their case in previous years, and will not be included in the current year's statistics for cases, even if this is the year in which they died.
However, the statistics do offer a broad comparison between the number of cases and deaths reported in a given year, which can help in illustrating the usual severity and survival rate of the cancer in question.
Equally, comparisons made between sets of data over time may have been slightly influenced by changes in the way Cancer Research or the NHS report their statistics.
The process of reporting cancer statistics is evolving, and methods change over time. This may lead to a slight fluctuation in statistics for cases, deaths, and rates of incidence and mortality.
RATES OF INCIDENCE AND MORTALITY
These two rates show how frequently the given cancer occurs in the UK population over a year.
They are worked out by dividing the total number of cases (incidence) or deaths (mortality) by the UK population, multiplying by 100,000, then age-standardising the result - in other words, adjusting the formula so that the result can be compared to different communities.
Age standardisation takes into account the spread of ages in the population being looked at, in this case the UK. The process removes the possibility that, when comparing cancer data, differences in rates are simply the result of people of different ages living in different communities.
This is why taking the 2005 total for cases or deaths, dividing by the UK population (e.g. 60,000,000) and multiplying by 100,000 will not produce the result for rates of incidence or mortality seen in the same graphic.
GREAT BRITAIN AND THE UNITED KINGDOM
Each of our graphics carries labels showing the parts of the world to which the data shown applies.
In the case of our cancer statistics, the majority of the data applies to the entire United Kingdom. These are marked "UK".
However, because of differences in the way data is captured and stored, some of our graphics do not include data for Northern Ireland. These are marked "GB" (or Great Britain).
In keeping with most major cancer research organisations, we have not included figures for non-melanoma skin cancer in our totals for overall cancer or skin cancer.
Non-melanoma skin cancer is the most common type of cancer, with more than 100,000 estimated UK cases each year, including many which Cancer Research suspects are not reported.
Most cases of non-melanoma skin cancer can be treated and cured, so these skin cancers are often excluded from national cancer statistics.
at 12:55 PM