More exposure to certain risk factors, less screening, often later diagnoses: the poorest French people have a significantly higher risk of developing cancers with a poor prognosis, a study on social inequalities in the incidence of cancer reveals on Thursday June 4.
“For a long time, we thought that cancer was a disease affecting the entire population indiscriminately”, but more recent, more detailed studies show “an extremely strong link with the situation of individuals, particularly socio-demographic”, underlined Thomas Wanecq, head of Drees, the statistical service of social ministries, during a decryption with the researchers at the origin of this work.
This service publishes a study confirming that cancer, the leading cause of death in France with more than 160,000 deaths each year, hits certain categories of the population harder, a reality already highlighted by other work.
New in this work: insight into social inequalities in incidence and severity at the individual level, which takes into account in particular the various locations of tumors. Its strength, according to its authors, also comes from its combination of Health Insurance reimbursement data with that of a permanent demographic sample from INSEE, between 2013 and 2020.
If we look at the organs affected, certain cancers are more common among the poorest, others among the wealthiest.
Lung cancer thus affects the poorest people much more often, the study points out. Between 2013 and 2020, men belonging to the bottom 10% had a 2.2 times higher risk of developing it than those in the richest 10%. Conversely, breast and prostate cancers are more common among wealthier French men and women.
Among the possible explanations put forward by researchers: differences in exposure to risk factors – such as smoking for the lungs, or previous use of certain contraceptive pills and a later age of pregnancy for the breast – and differences in the use of screening, particularly for the prostate.
But the poorest people more often develop cancers associated with lower chances of survival (with a 1.7 times higher risk of cancer with a poor prognosis for the poorest 10% compared to the wealthiest 10%) and suffer more aggressive forms.
“Multi-stage” inequalities
The time of diagnosis is also associated with strong inequalities. Detecting cancer at an early stage makes it easier to treat, but also to limit the after-effects of the disease and certain treatments.
For breast, colorectal or cervical cancers, subject to organized screening, diagnoses occur more often while there are metastases for the most modest ones. For undetectable cancers, these differences with the wealthiest do not appear. However, “the poorest have less recourse than the most advantaged” to the three national screenings, due to financial constraints but also information and connection to care, showed another study by the Drees in February.
For lung cancer, the most fatal malignant tumor in France, a pilot screening program started in mid-May in five regions. Twenty thousand smokers or ex-smokers aged 50 to 74 must benefit from chest scans, monitoring and, if necessary, medical treatment.
Another inequality exposed by the study unveiled on Thursday: “avoidable” cancers, linked in particular to tobacco or alcohol, are more frequent among the poorest – the risk is more than twice as high for the least advantaged 10% compared to the wealthiest 10%.
“These results highlight that social inequalities in the face of cancer are built at several stages: exposure to risk factors, recourse to screening and early diagnosis,” concludes Drees in a press release, warning about prevention.
However, its work is based on data prior to the development of Health Insurance initiatives targeting populations that use screenings the least. The impact of these “go towards” actions will be evaluated later, according to the researchers. In the fall, Drees will publish a study exploring specific questions related to cancer mortality and survival.
