Rise in cancers in people under 50: “Obesity and a sedentary lifestyle are risk factors”

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The increase in cancers in young adults, from 19 to 50 years old – noted by the scientific study published in Nature Reviews Clinical Oncology, is it verified in France? Director of the Tarn Cancer Registry, epidemiologist member of the High Council for Public Health and of the Inserm Equity research team, Dr Pascale Grosclaude answers and recalls the basics of effective prevention. Interview.

A study published in Nature Reviews Clinical Oncology notes an increase in cancers among young adults – 19 to 50 years old – since the 90s. Is this true in France?

What this American study shows is that there are geographical areas (United States, Australia, New Zealand, Canada, United Kingdom, Sweden, South Korea, Slovakia, Ecuador and Uganda, editor’s note) where some cancers increase. However, the same cancers are not increasing in all countries. Regarding France, we do not see any major increase, at least not for the list given in this article. But whether the age at which adult cancers are diagnosed is falling is a real question. Cancer is primarily a disease that increases with age. There are quite a few before 50 years. However, we observe that the frequency of certain cancers increases among 19-50 year olds, but often as they also increase among the oldest.

On which cancers is it observed, for example?

If we take esophageal cancers as a whole, we observe a decrease but for the particular form of adenocarcinomas, the increase exists for all ages and it is slightly higher in young people. Since 2005, colon cancer has been on the rise in people in their forties, a finding that also applies to rectal cancer in women. Regarding liver cancer, we are also facing an overall increase, but lower in young adults. Cancer of the gallbladder and of the biliary tract is experiencing changes in them comparable to those of other age groups, with an increase in men and a decrease in women. Skin melanoma is increasing for all age groups, men and women, like kidney cancer where we see that the incidence rises faster in young adults. The incidence of breast cancer is also increasing. But the most worrying is pancreatic cancer, with a rapid and significant increase in all age groups. As the prognosis is generally very poor, it is a major problem and that is why it is one of the priorities of the cancer strategy in France. But we can also note the stability and the decline of many other cancers: ENT, stomach, cervix or prostate.

Are these increases the result of better screening today, or of more intense exposure to certain risk factors?

With regard to kidney and breast cancer, this is particularly linked to screening, which enables earlier diagnoses to be made in younger people, as well as to progress in medical imaging. If, for example, a person undergoes a CT scan for another pathology, this examination can today reveal a tumor on a deep organ such as the kidney that we would not necessarily have seen in the past and the prognoses for recovery are very good. . But for the rest, it is obvious that the Western way of life is in the hot seat: apart from tobacco and alcohol, which have been well identified for a long time, obesity and a sedentary lifestyle – like several pollutants present in the environment – are risk factors for many cancers. It is therefore not surprising to observe an increase in their frequency, including in younger people than what was observed before. What we observe is a generation effect. The “old adults” of today walked more and ate less – and especially less fat and less sugar in their youth – than did the “young adults” subjected from childhood to this Western way of life. We must expect an increase in certain cancers but also in other chronic diseases and as this way of life is gradually imposing itself on the rest of the world, this is observed in many countries.

Why isn’t there better prevention?

We know very well what to do in prevention. It is necessary to attack the causes but also “the causes of the causes”. We cannot content ourselves with making people feel guilty about their diet, by telling them to cook healthy products themselves when many have neither the means nor the time. We cannot make speeches about cycling and walking when the development of cities and of the entire territory does not lend itself to it. Prevention is based on a change in individual behavior in an environment favorable to these changes. Currently he is hostile to it: fat and sugar are a choice of society guided by the economy. Humans have a craving for sugar, which is a drug. Manufacturers know this and sell us sugar, but also processed meals which, it is true, also respond to current lifestyles. It is therefore structural reforms that are needed because it is precisely these lifestyles and production that should be changed. That’s what the quoted article says.

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