The Causal Effect of Education on Cancer Risk and Survival in England and Wales

Cecilia Potente, University of Oxford

Education might affect cancer risk and survival through greater access to resources connected to prevention and cancer treatments. However, only few studies have tried to understand the causal effect of education. This quasi-experimental design exploits the exogenous variation in years of education due to compulsory schooling law changes in 1947 and 1972 in England and Wales. The data source is the ONS Longitudinal Study (ONS LS). The identification of the causal effect of education on cancer risk and survival is achieved using the regression discontinuity framework. The effect of these reforms on educational attainment is found large. Therefore, this work tests the presence of discontinuous changes in the hazards of developing and surviving cancer. The focus on both incidence and survival could shed light on different mechanisms connecting education and cancer. Understanding better causes of educational inequalities in cancer is extremely important given widening diffusion for this morbidity.

Cancer is becoming an increasingly common disease especially due to the aging population and the reduction in infectious diseases fatalities. Previous studies have documented the existence of an association between educational attainment and cancer risk and survival. Education might influence cancer incidence and survival through greater access to resources in terms of prevention and cancer treatments. However, only few studies have analyzed the causal effect of education on cancer. My work has the aim of analyzing the causal effect of education on cancer incidence and survival in England and Wales. I exploit the exogenous increase in education due to the compulsory schooling law changes in 1947 and 1972 in England and Wales. This analysis takes advantage of these two reforms in order to identify the causal effect of education on cancer risk and survival.

Compulsory school laws in Britain define the maximum age at which children should start education and minimum age at which they are allowed to leave education. Consequently, these laws determine how many years children spend in compulsory schooling. During the 20th century two legal changes have risen the minimum ages at which children were allowed to leave school. The economic and social contexts surrounding these two changes were quite different offering a more complete view of the causal effect of education on cancer risk and survival. Therefore, it results interesting to explore the causal effects of education on cancer for reforms happening in different time periods. Compulsory school law changes have been used to identify the effect of education on cancer incidence in Norway and Sweden. However, England and Wales have much more stratified societies where social inequalities in health are larger than in Nordic countries. It remains an open question whether different institutional settings affect differently education on health. Moreover, the association between cancer risk and education is highly dependent on the type of cancer. On one side, higher educational attainment reduces the risk of development of some cancers, such as colorectal, cervical and lung; on the other side, the opposite educational gradient is observable for skin, testicular, prostate and breast cancer. Finally, leukemia and lymphoma incidences are not associated in any direction with education. Socioeconomic differences in cancer survival are more pronounced than the ones in cancer incidence.

The data source is the ONS Longitudinal Study (ONS LS) for England and Wales. ONS LS contains census linked information concerning vital events for 1% of the population of England and Wales from 1971 to 2011. Events registered are births, deaths, immigrations, emigrations, and cancer. In particular, I make use of the linkage with National Cancer Registry which records several information concerning the age at diagnosis, stage and type of cancer. Data are also linked to death records allowing for examining cancer survival. The sample members followed longitudinally across different censuses (1971-2011) are around 500 thousand. Among those, 135 thousand experience a cancer event and they have information concerning their diagnosis and survival to the disease. The aim of this work is the identification of the causal effect of education on cancer risk and survival using changes in compulsory school laws in England and Wales. The identification is achieved through a regression discontinuity approach. The reforms have a clear effect on educational attainment of different individuals. First, in order to study how education is causally related to cancer risk and survival, I estimate multistate hazard models: the hazard of developing cancer and subsequently the hazard of death are estimated using age and month-year birth cohort fixed effects. Second, once these month-year birth cohort fixed effects are calculated, I use them as outcome variables in local linear regression models. From these local linear regressions the discontinuous changes in the hazard of developing and surviving cancer are estimated. These are going to be our parameter of interest. The proposed work aims at providing evidence on the causal effect of education on health focusing on cancer incidence and survival in England and Wales. Understanding better causes of educational inequalities in cancer is extremely important given the increasing number of people affected.

Presented in Session 1170: Health, Wellbeing, and Morbidity