A new report shows differences in cancer risk between rich and poor areas of London.
Laura McRobb
Cancer Inequalities in London 2000–4, published by the Thames Cancer Registry (TCR) at King’s College London, includes information and statistics relating to 15 common forms of cancer.
The report finds a significant decrease between 1985 and 2004 in the incidence and mortality rates of lung cancer and bladder cancer in males, stomach cancer in both sexes and cervical cancer in females. Decreases in the mortality rates for colon cancer and breast cancer are also noted.
However, between 2000 and 2004, the incidence and mortality rates occurring from lung cancer and stomach cancer were higher in both males and females living in areas of London defined as ‘deprived’, than in those defined as ‘affluent’.
Furthermore, in females living in deprived areas, incidence and mortality rates of cervical cancer were also higher than for those living in affluent areas of London.
For both lung and cervical cancer, the highest rates of incidence and mortality were observed in North East and South East London.
A baseline for addressing inequalities
TCR is a registry dedicated to compiling information about cancer across London and the South East Coast area. It documents all new cases of cancer, and produces statistics relating to the incidence of cancer, its epidemiological distribution in the population and the survival of patients after diagnosis.
The report, written by a Registry team including Professor Henrik Møller (TCR director) and Dr Elizabeth Davies (senior lecturer at TCR), aims to help understand and prevent cancer inequalities within London. According to Davies, it provides “a baseline for future recommendations focussing on these inequalities”. Davies stresses, however, that the report “does not show that Londoners in different groups are being treated differently”.
Deprived or affluent? Geographical analysis explained
To determine whether particular areas within London were affluent, deprived, or in a category in between, the ‘Income domain of the Index of Multiple Deprivation’ (IMD 2004) was used. This provides information on one component of socio-economic deprivation based on figures for the level of income and welfare benefits of residents in any area.
Lower super output areas (LSOA)—areas including around 1000 households—were divided into five groups based on their income scores. Patients were allocated to one of these deprivation groups according to the LSOA they were living in. Davies highlights that the measures are “not therefore an individual measure of income or
risk but an area-based measure”
Why such inequality?
The socio-economic reasons influencing risk for different cancers are not always easy to pin down. While the analyses show reinforce the strong link between smoking-related cancers and socio-economic deprivation, Davies notes that there are numerous factors that may also contribute to inequalities. It is important to consider that there may be different factors affecting incidence and different ones affecting survival. Davies comments, in terms of survival differences, “We do not know where in the chain of causality the socio-economic inequalities we see in survival are taking place,” says Davies. “Are patients arriving at diagnosis with the same stage of disease? Are people in deprived areas presenting later? Is there a difference in access to or uptake of treatment?”
Continued analysis over a longer period will further show if the recently implemented smoking bans will have any effect on the incidence and mortality of lung cancer and other smoking-induced cancers. Evidence from other countries that have implemented smoking bans is that we can expect to see a reduction in the rate of heart attacks well before seeing any effects on the cancer rates.
Where now?
The findings presented in the report are a crucial step, allowing further detailed studies to take place. According to Davies, those in cancer networks and primary care trusts have been given one month to read the report, interpret the data and then come back to the TCR with further questions. The TCR will then “work with colleagues in NHS London to tease out where you could make recommendations based on the information we already have”. Studies will then aim to examine why such inequalities may be occurring in order to try and prevent them in the future.
Image produced by the Thames Cancer Registry, King’s College London using information from the Income Domain of the Index of Multiple Deprivation (2004)