Increase in cancer cases in people under 50: “Obesity and a sedentary lifestyle are risk factors”

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The increase in cancer cases in young adults, from 19 to 50 years – 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 reminds us of the basics of effective prevention. Interview.

A study published in Nature Reviews Clinical Oncology notes an increase in cancer rates among young adults—ages 19 to 50—since the 1990s. Is this the case in France?

What this American study shows is that there are geographic areas (USA, Australia, New Zealand, Canada, Great Britain, Sweden, South Korea, Slovakia, Ecuador and Uganda, editor’s note) where some cancers are increasing. However, the same cancer cases are not increasing in all countries. As for France, we don’t see any major increase, at least not for the list 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 types of cancer is increasing among 19-50-year-olds, but often as they also increase among the oldest.

In which cancers is it observed, for example?

If we take cancer of the esophagus as a whole, we observe a decrease, but for the particular form of adenocarcinomas, the increase is found for all ages, and it is slightly higher in young people. Since 2005, colon cancer has been increasing among people in their forties, a finding that also applies to rectal cancer in women. In terms of liver cancer, we are also facing an overall increase, but lower in young adults. Cancers of the gallbladder and bile ducts experience changes in them comparable to those in other age groups, with an increase in men and a decrease in women. Skin melanoma is on the rise for all age groups, men and women, as is kidney cancer, where we see incidence rising more rapidly 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. Since the prognosis is generally very poor, it is a major problem and therefore one of the priorities of the cancer strategy in France. But we can also notice the stability and decline in many other types of cancer: ENT, stomach, cervix or prostate.

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

In the case of kidney and breast cancer, this is particularly linked to screening, which enables earlier diagnoses in younger people, as well as advances in medical imaging. For example, if a person undergoes a CT scan for another pathology, today this examination can reveal a tumor on a deep organ like the kidney, which we would not necessarily have seen before, and the prognosis for recovery is very good. . But for the rest, it is obvious that the Western lifestyle is in the hot seat: apart from tobacco and alcohol, which have been well known for a long time, obesity and a sedentary lifestyle – as well as several pollutants in the environment – ​​are risk factors for many types of cancer. It is therefore not surprising to observe an increase in their frequency, also in younger people, than what was observed before. What we observe is a generational effect. Today’s “old adults” walked more and ate less – and especially less fat and less sugar in their youth – than the “young adults” who were exposed to this Western lifestyle from childhood. We must expect an increase in certain types of cancer, but also in other chronic diseases, and as this way of life gradually imposes itself on the rest of the world, this is observed in many countries.

Why isn’t there better prevention?

We know what we have to do in prevention. It is necessary to attack the causes, but also the “causes of the causes”. We can’t just make people feel guilty about their diet by asking them to make healthy products themselves when many have neither the money nor the time. We cannot make speeches about cycling and walking when the development of cities and the entire territory is not suitable for it. Prevention is based on a change in individual behavior in an environment favorable to those changes. At the moment he is hostile to it: fat and sugar are a social choice guided by the economy. Humans have a craving for sugar, which is a drug. Industrialists know this and sell us sugar, but also processed meals, which admittedly also respond to the current lifestyle. Structural reforms are therefore needed, because it is precisely this lifestyle and production that must be changed. That’s what the cited article says.

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