How does our social environment influence our chances of getting cancer? New research using Census data by Professor Robert Hiatt and colleagues shows there is a link between socio-economic status and cancer incidence, but also throws up some unexpected findings. In the first of a series of three blogs on socio-economic links to cancer, he discusses his work.
It’s well known that specific health outcomes are affected by socio-economic status – for instance the Whitehall IIlongitudinal study of civil servants clearly demonstrated this relationship as did subsequent Marmot reviews including the 2010 Marmot review of health inequalities. Recent research using the ONS Longitudinal Study has shown us in more detail the connections between socio-economic status and cancer survival, but we also wanted to look at how our background might be connected with the onset or incidence of different cancers as well as with their outcomes.
We now know that people from more deprived backgrounds have lower survival rates when they have cancer, although the causes of this are multi-faceted. We know that those with higher social status have access to critical knowledge, money, power, prestige, and social connections, which plays out to their benefit for cancer as well as any number of other health outcomes. There is a complex interplay between these fundamental aspects of their lives and their incomes, occupations, education, income, education, culture migration status and sexual orientation. And that in turn affects the material resources they have, their food security, their internet access, the type of healthcare they can access, their exposure to discrimination and stigma, and the support networks on which they can rely.
Those with lower socio-economic status on the other hand are missing out on many of the fundamental underpinnings leading to good health and in addition are more likely to be exposed to things like environmental toxins and climate change. In some cases, they may also be more likely to adopt unhealthy behaviours, such as smoking or a lack of physical activity. So, when it comes to the social determinants of cancer, the picture is multi-level, complex and a challenge to understand.
The ONS-LS can’t tell us everything about the possible links between social determinants and cancer, but it does allow us to look at different types of cancer diagnoses by occupational status, level of education and household characteristics, as well as by the type of area in which a person lives.
We were able to take data on almost 140,000 individuals who were alive in 1971, based on a one per cent random sample from the census, and look at the types of cancer diagnoses among them taking into account some of these social factors.
Two major questions
We asked two major questions: How does socio-economic position, measured both by area of residence and by individual characteristics, relate to cancer incidence and mortality? And how do social factors such as education, social class, occupation, home location and prior health status contribute to the relationship between socio-economic position and cancer outcomes?
We looked at all the major types of cancer – the biggest are lung cancer, breast cancer, colorectal cancer and prostate cancer. Overall incidence (onset of new cancers) tended to be higher among those with lower socio-economic status. But of course, behavioural factors such as smoking could be instrumental in that relationship and there is no data on smoking status in the ONS LS. So we looked again after eliminating those cancers with links to tobacco – and still found the same effect.
When we looked at individual cancers rather than overall rates, a rather different picture emerged. For those from lower social groups, there was a higher risk of being diagnosed with lung cancer, cervical cancer and stomach cancer. But those groups actually had a lower likelihood of contracting breast cancer, prostate cancer or melanoma. The relationship went in opposite directions depending on the cancer site. There were some also major cancers including colorectal cancer for which there wasn’t a clear social pattern.
We examined this relationship both through the lens of respondents’ income and education, and by the area in which they lived, and we came up with similar findings.
So what are the implications? At this stage, the full picture isn’t clear. We can say that overall, those from poorer backgrounds are more at risk of contracting cancer. And we know the reasons for that are complex. Lung cancer is certainly linked to smoking, so that must be a factor – and these social groups may also have higher exposure to the human papillomavirus (HPV), the major cause of cervical cancer, or to H. pylori bacteria, which live in the digestive tract and are linked with gastric cancers.
We can also say that those from wealthier backgrounds are more at risk from certain types of cancer. We may speculate that in some cases there will be behavioural and social factors at work – for instance, women who have children later in life or remain childless are at greater risk of breast cancer. These may tend to be the more highly-educated women who want to pursue their careers. But at present we don’t have any good theories on why prostate cancer might be more common among men from higher socio-economic groups. So our research raises questions as well as answers.
Our measures of individual socio-economic position are based on crude categories of income, education and occupational status, but may not give us a full picture. And we haven’t yet interpreted our findings in the context of the societal changes which has taken place since 1971.
There is much more work to be done in this area. We plan to publish three papers; one on socioeconomic status and cancer incidence, a second on socioeconomic status and mortality and a third comparing incidence with mortality. There will be detailed studies of individual cancers, too – so the ONS-LS will continue to prove a rich resource for cancer researchers in this and other areas.
Robert Hiatt’s presentation on Social Gradients in Cancer Incidence (and Mortality): the ONS Longitudinal Study was given on May 23, 2022 at University College London, and was based on forthcoming research with Nicola Shelton, Wei Xun and Eduardo Santiago-Rodriguez.