The increase in cancer cases among young adults has oncologists on edge. So much so that the congress of the European Society for Medical Oncology (ESMO), held a few days ago in Barcelona, dedicated a talk to address this issue and the room was packed. Hundreds of oncologists from around the world attended the event. the presentation by Shuji Ogino, professor of Epidemiology at Harvard Medical School, on this “emerging global epidemic” that is driving specialists crazy. According to a study published in the journal BMJ Oncology, Tumours in people under 50 have increased by almost 80% in three decades, but scientists have not yet managed to fully understand this phenomenon. Experts say that current lifestyle habits are having an influence, although this variable alone may not explain everything. According to Ogino, the increase in early-onset cancer is only “the tip of the iceberg” of a global rise in chronic diseases over several generations.
“We are seeing an increase in cases in young patients and we are concerned because it is not always related to a specific cause,” confirms Angela Lamarca, an oncologist at the Jiménez Díaz Foundation and spokesperson for the ESMO congress. This emerging dynamic has been most studied in colorectal cancer, but it also occurs in other tumors, such as pancreatic, esophageal, kidney, liver, bile duct, gallbladder, stomach, head and neck, and breast cancer, among others. “Several studies have been done to analyze whether there is a molecular cause that explains why more cases occur in young patients and, many times, we have been surprised to find that, at a molecular level, young patients have tumors very similar to those that occur in older patients. We still need to investigate and understand more if there is something at a molecular level that we have not been able to identify or if it is something related to risk factors,” says Lamarca.
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The origin of early-onset cancer is not clear. It is probably multifactorial. Researchers believe that, although greater and better detection of certain tumors may have had an influence, this would not explain the increase in overall cases, since some do not have early detection tests and, in addition, most screenings are usually carried out after the age of 50, not before. Family history and hereditary syndromes, on the other hand, may justify a portion of new diagnoses, but they are not the most frequent profiles either. Most cases are sporadic (without a family or hereditary link) and remain without a clear explanation.
Lamarca gives the example of pancreatic cancer. They are seeing cases of 40-year-olds, when it was usually seen in people over 65: “We thought that maybe young patients developed pancreatic cancer for some reason that made them have a higher risk, but we have not always found it. It is true that there are hereditary syndromes, such as BRCA.” [personas que presentan mutaciones en estos genes]which is also associated with breast and ovarian cancer, which can justify pancreatic cancer in a young person, but they are not all young patients we find. So, why do these young patients develop pancreatic cancer that when we analyze it at a genetic level is the same as that seen in a 65-year-old? We don’t know,” laments the oncologist.
What is clear to the scientific community is that (bad) lifestyle habits play a fundamental role. Western diets (rich in carbohydrates and processed foods) do not help. promote obesity, Nor is it a sedentary lifestyle or toxic habits such as tobacco and alcohol, explains David Páez, an oncologist specialising in digestive tumours at the Hospital Sant Pau in Barcelona: “The risk factors are the same as those for cancer in older adults, but it is not known whether there is something else influencing the development of cancer so early only due to these factors and in some populations,” he outlines. The study itself, published in BMJ Oncology concludes that “dietary risk factors, alcohol consumption and tobacco consumption were the main risk factors for the major early-onset cancers” recorded in 2019. But it adds that “prospective cohort studies throughout life are needed to explore the etiologies [las causas] of early-onset cancers.”
Risk exposures from childhood
What matters is the present, current behavior, but also yesterday and the entire environment in which a person has developed throughout their life. And even before being born. Páez points to the key role of the exposome, which are all those non-genetic factors to which an individual is exposed throughout their life and which condition their health: “The interaction of these external factors with the genome can condition the appearance of diseases. It is thought that these factors may be altering people’s immunity or the composition of the microbiome from the prenatal period.”
Along the same lines, they reflect on a study a group of Harvard researchers (including Ogino) and highlights that the earliest phase of carcinogenesis could begin very early: “Exposures in utero can lead to cellular reprogramming, including epigenetic alterations, which could have long-lasting effects on susceptibility to chronic diseases.” In fact, they suspect that reproductive factors (age at onset of menarche, whether or not breastfeeding was done, fertility rate, use of oral contraceptives, etc.), as well as smoking, diet, alcohol consumption, lifestyle and previous illnesses of the mother during pregnancy “could be relevant intrauterine exposures.”
Exposure to long-term risk factors begins in the first years of life. What we see now is the result of decades of exposure.”
Shuji Ogino, Professor of Epidemiology at Harvard Medical School
In this regard, during the presentation at ESMO, Ogino again stressed that early-onset cancer is probably influenced by “nature and nurture”. “Exposure to long-term risk factors begins in the first years of life. What we see now is the result of decades of exposure,” he recalled. What scientists are also unclear about is how much each risk factor weighs at a given time in life and how they interact with each other.
Precisely because of the long latency period of cancer and the change in exposure to various environmental and life factors, experts emphasize the importance of the birth cohort effect in colon cancer. This means that each generation experienced a higher risk of early-onset cancer than the previous one. a podcast from the magazine ScienceKimmie Ng, a researcher at the Dana-Farber Cancer Institute in Boston (USA), who has described The rise of colorectal cancer in young adults, he explained, “is something that is affecting generation after generation, where people born in 1990 have a significantly higher rate of developing colorectal cancer compared to people born in 1950.” He added: “We think it is due to environmental exposure. To what exactly? We don’t know. Again, we have looked at obesity, we have also looked at sedentary behavior, higher consumption of sugar, sweets and drinks, lower levels of vitamin D, and they all seem to be associated with increased risk, but I don’t think that is all that explains what is happening.”
Late diagnoses
Scientists are also investigating the specific characteristics of these early-onset tumors, but it is a field full of unknowns. To begin with, these tumors are unpredictable, as there are no early detection tests to anticipate diagnosis or screenings that appeal to these ages (usually from 50 years of age). At the clinic, oncologists point out that they are discovered in advanced stages: “They are usually detected in symptomatic stages. In the case of colon cancer, for example, when there is bleeding with stool, abdominal pain or changes in bowel habits. What is seen is a delay in diagnosis with respect to older adults and in young people it takes about six months longer to diagnose,” explains Páez.
Some research also warns that these are more aggressive tumours, but it is not clear whether this is due to the biology of this cancer itself, which is more virulent, or to the fact that it is diagnosed in advanced stages. “In colon cancer, it is not clear whether there are molecular differences between tumours in older and younger adults. The worse prognosis is attributed more to the delay in diagnosis,” says the oncologist from Sant Pau. An article Researchers at the University Hospital of Navarra, who have designed a study to analyze early-onset cancer in northern Spain, broaden the focus and assure, however, that early-onset gastrointestinal tumors “occur in advanced clinical stages and with aggressive phenotypes.”
In any case, the approach to these patients poses new challenges for specialists. The treatment is the same as for older adults, but the consequences of this diagnosis are different for the young population, warns Páez: “It is a challenge from the point of view of the consequences that may remain due to the type of treatment or surgery and its impact on quality of life. And then, the long-term risk of developing another cancer is also greater.” The oncologist also points to more psychosocial problems, stigma, mental health problems and impact on working life or even on reproductive or sexuality-related aspects.
For now, the tools to tackle this phenomenon are limited. “Dissemination and awareness” about the situation, avoiding risk factors and continuing to investigate, says Páez, to see if it makes sense to lower the age of screening (this has been done in the United States, but is still being discussed among scientists) and to find tools for early detection.
Pedro Pérez Segura, member of the Permanent Commission of the ECO Foundation and head of Medical Oncology at the San Carlos Clinical Hospital (Madrid), also advocates “educating” citizens to improve their lifestyle: “We are witnessing a new boom tobacco and alcohol in the younger population. And we live in a time in which a sedentary lifestyle is important. We must reinforce health education to avoid all this and also remember the importance of sun protection because the incidence of skin lesions is also increasing.”
Lamarca also calls on the population to seek medical attention when they have symptoms, and not to underestimate them: “If they have symptoms, they should go to the doctor. Often, a young patient may have symptoms such as weight loss, abdominal pain or other non-specific things, and they don’t give it much importance because they say: ‘how can it be cancer if I’m 40 years old? ’ The reality is that there are more and more cases of cancer diagnosed in the young population and often they are diagnosed later, precisely because they don’t go to the doctor, because they minimize the symptoms.”
