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Danish study links cancer survival to income and education

BMJ 2008; 337 doi: https://doi.org/10.1136/bmj.a1340 (Published 20 August 2008) Cite this as: BMJ 2008;337:a1340
  1. Roger Dobson
  1. 1Abergavenny

    People with more education or a higher income are likely to live longer after a diagnosis of cancer than those who are less well educated or poorer, suggests a large investigation into cancer and social inequality.

    More than 50 researchers, whose 21 papers will appear in a special issue of the European Journal of Cancer, looked at incidence and survival from different types of cancer among 3.2 million people in Denmark.

    Their summary paper states that around six out of 10 men (62%) with a basic education, defined as 7-12 years of primary and secondary schooling, were alive one year after their diagnosis, whereas the figure among men with higher education, defined as 13 or more years of education, was 73% (European Journal of Cancer doi: 10.1016/j.ejca.2008.06.018). A similar difference was found among women: 72% and 82%, respectively.

    “Our study shows that inequalities in cancer incidence and survival must be addressed in all aspects of public health, with interventions both to reduce incidence and to prolong survival,” say the authors of the summary paper, from the Danish Cancer Society.

    “[This study] shows that, even in an egalitarian, developed country, social inequality has not been completely banished from public health. Our results are relevant for all societies in which health interventions are established in accordance with the goal of equal access to public services.”

    All 3.2 million people were born between 1925 and 1973. They were followed up for cancer incidence between 1994 and 2003 and for survival between 1994 and 2006. A total of 147 973 cancers were diagnosed, just over half the cancers diagnosed in Denmark during that period.

    From various Danish registers the researchers gathered a wide range of health related indicators and socioeconomic and demographic data, including educational attainment, disposable income, employment, cohabitation status, and ethnicity.

    Their results showed a consistent association in the incidence of cancers of the mouth and pharynx, larynx, oesophagus, stomach, lung, kidney, and cervix with shorter education and lower income. All these cancers are associated with smoking.

    Conversely, a higher incidence of breast and prostate cancers and malignant melanoma was associated with higher education and income. Pancreatic and bladder cancers were found to be associated only with educational attainment: the risk of these cancers was lower with increasing length of education.

    For most cancers, relative survival at one and five years after diagnosis differed strikingly with education and income level: the least educated and poorest participants had the worst survival. For some cancers—primarily those, such as lung cancer, with overall low survival—social differences were seen after one year but had almost disappeared after five years.

    “For all cancers together, an approximately 10% difference in survival between those with the highest levels of income and education and those with the lowest was already apparent after one year. The difference was only 1-2% greater after 5 years,” says the summary report.

    Notes

    Cite this as: BMJ 2008;337:a1340

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