Three years ago, a team of prestigious scientists asked a disturbing question: “Is there an emerging global epidemic of ?” The researchers, from Harvard University (USA), had detected a general increase in the incidence of 13 types of tumors in people between 20 and 49 years old in almost fifty countries between 2002 and 2012. The authors themselves pointed out possible causes: sugary drinks, alcohol, junk food, sedentary lifestyle, childhood obesity, antibiotic abuse, pollution. A similar analysis of the latest international data, led by the Spanish epidemiologist, now reveals a much more complex phenomenon: cancer cases are increasing among younger adults, yes, but only in some types of tumors and also in people over 50 years of age. Can we then speak of a global epidemic?
The new study has only detected a general increase in the incidence of six types of cancer among younger adults: thyroid (with an increase of 3.6% each year), kidney (2.21%), (1.66%), colorectal (1.45%), breast (0.89%) and leukemia (0.78%). “All of them — except — also increase among those over 50 years of age. Therefore, if we talk about a “global epidemic” that exclusively affects young adults, we could only refer to colorectal cancer,” says García Closas, from the , in London.
The epidemiologist and her colleagues have analyzed official data from 42 countries in the period 2003-2017. Spain, which deals with tumors, has been left out of the research because its available data only reached 2016, according to García Closas. The great novelty of their study is that it is not limited to examining the incidence of cancer among young adults, as the Harvard team did, but for the first time it makes an international comparison with what is happening in those over 50 years of age. “It is important to recognize that some types of cancer are increasing among young people, but focusing attention exclusively on this group can lead to erroneous interpretations. There is a risk of inefficient allocation of resources for research and prevention if the fact that cancer continues to be predominantly a disease of older adults is neglected,” says the researcher, born in Barcelona 58 years ago.
The analysis shows an increase in incidence – similar to that of younger people – in those over 50 years of age: thyroid (3%), kidney (1.65%), endometrium (1.20%), breast (0.86%), leukemia (0.61%). In the case of colorectal cancer, an average increase of 0.37% is detected, but only in half of the countries examined. “The six types of cancer that show global increases are related to obesity, both in youth and in adults, and the prevalence of obesity has increased in many of these countries. Therefore, it is likely that this explains part of the observed increase, although we do not believe that it explains everything. It is important to continue investigating other possible causes,” says García Closas. Faced with doubts about the existence of a true cancer epidemic in young adults, the World Health Organization does clearly speak of a “”. Some are obese, a risk factor for suffering from malignant tumors and other diseases.
García Closas emphasizes that greater surveillance and improved diagnostic techniques could also explain part of the increase in some types of cancer. Altogether, the incidence of the eight tumors with the greatest increase in those under 50 years of age in the United States has doubled since 1992, but their aggregate mortality has not changed, according to what was published three weeks ago by the American doctor, author of the book, in which he denounces that excessive medical tests end up turning healthy people into sick people. For Welch, the detection of lesions that would have been basically makes the increase in early-onset cancer in the United States “more apparent than real.”
The incidence of four types of cancer, in fact, is declining in younger adults in more than half of the countries, according to the analysis by García Closas and his colleagues. Stomach cancer falls 1.62% annually. That of the esophagus, 0.92%. Oral, 0.42%. The liver, 0.14%. “All these cancers are associated with alcohol consumption, so it is possible that a reduction in consumption in some countries is helping to explain, at least in part, the observed trends,” reflects the epidemiologist, who has spent her entire working life between the United Kingdom and the United States, without ever working in Spain. Their results are published this Monday by the United States College of Physicians.
The new analysis paints a picture in which the incidence of tumors linked to obesity increases, both in young adults and those over 50 years of age, with colorectal cancer as a true “global epidemic” among people between 20 and 49 years of age. The epidemiologist, who has not participated in this study, is forceful. “These findings should not alarm us, but rather lead us to action,” he says. In his opinion, we must invest more in research to clarify the mechanisms of colorectal cancer, refine early detection programs and intensify prevention, through healthy eating, physical activity and control of weight and alcohol consumption.
“Although public attention is rightly focused on the increase among young adults, the absolute burden of cancer continues to fall on the elderly and will grow in the coming decades. In 2020, the elderly accounted for new diagnoses and 71% of cancer deaths. By 2040, a substantial additional increase is expected. Therefore, strategies must simultaneously consider both ends of life,” emphasizes Martín Moreno, professor of Preventive Medicine and Public Health at the University of Valencia.
The epidemiologist from Harvard University led the study that three years ago detected a general increase in the incidence of 13 types of tumors in young adults. His team used the same database used by Montserrat García Closas, that of , but without analyzing those over 50 years of age. When consulted by EL PAÍS, Ogino responds that he “basically agrees” that the new data confirms that the increases in incidence are not specific to younger people. “I think the most important message is that the incidence of cancer will increase in all age groups as the current young generations age in the near future, unless good prevention measures are taken,” he warns.
