In recent years, researchers have noticed a gradual increase in certain cancers in young adults. Early cancers, which affect people under the age of 50, have an increase. This tendency, although complex, is linked to several factors, according to experts.
A discreet but persistent trend
According to a recent analysis, 14 different types of cancer in young people are increasing, the most marked being those of the breast, colorectal, renal and uterine. These modest increases could accumulate over time, even if the overall incidence of early cancers remains low. Although rare, an increase of a few percent per year becomes significant over several decades, according to Miranda Fidler-Benaoudia, epidemiologist at the University of Calgary.
To better understand the evolution of diagnoses, a team led by Meredith Shiels, epidemiologist at the National Cancer Institute, analyzed the cancer data detected between 2010 and 2019 in people aged 15 to 49. Published in the journal Cancer Discoverytheir research classifies the results according to three age groups: 15-29, 30-39 and 40-49 years.
The results show a continuous increase in breast and uterus cancer in all age groups, while colorectal and kidney cancers have mainly increased in age groups 30-39 years and 40-49 years. Together, these four types represented more than 80 % of the additional cases observed in 2019 compared to 2010. Other types of short cancer include melanoma, cervical cancer and that of the stomach, although their incidence remains marginal.
The causes of such progression
The reasons for this increase are varied and often depend on the type of cancer. Among the potential factors mentioned, obesity often comes up. It is associated with several cancers increasing, notably those of the colon, the kidney and the uterus. The number of overweight or obese adults has increased spectacularly in the world since 1990. If research on cancer and obesity mainly concern the elderly, it is plausible that excess weight in young people also plays a role in this evolution. In 2019, more than half of the uterus cancers were associated with obesity, according to a recent study.
Regarding breast cancer, changes in reproductive behavior could also be involved. Women now have their first rules earlier, have fewer children and become mothers later than before, as many factors known to increase the risk of certain types of breast cancer. In addition, although the contraceptive pill can have a slight protective effect against certain cancers, it is also suspected of increasing the risk of breast cancer.
Another explanation for this increase could be linked to better detection. Some people, in particular those with genetic mutations such as BRCA genes or Lynch syndrome, present an increased risk of cancer and are subject to early screening. Advanced medical imaging (MRI, scanners) also make it possible to detect certain cancers earlier, such as renal carcinoma.
Environmental factors, including exhibitions during childhood or even the prenatal period, could play a role in certain early cancers. For example, a study published in April in the journal Nature evokes a molecule produced by certain strains ofE. coliColibactin, which could cause genetic mutations promoting colorectal cancer in young people. However, demonstrating a direct link between exposure and cancer remains complex.
Reduce risks, even without certainty
Even in the context of such research, it remains difficult to draw final conclusions. Cancers in young adults remain relatively rare, which complicates the constitution of sufficiently large samples for reliable statistical analyzes. Long -term research would take, depending on people over several decades, to better understand these causes, explains Meredith Shiels.
Although it is impossible to completely eliminate the risk of cancer, certain measures may reduce probabilities in the population. Protecting yourself from the sun, being vaccinated against papillomavirus (HPV), avoiding alcohol and tobacco are part of the known and effective prevention gestures.
« These practices can reduce the risk of cancer at any age, not just 50 years old “Recalls Tomotaka Ugai, cancer specialist at Harvard and the Brigham and Women’s hospital. In addition, this form of cancer is increasing in those under 50 years old worldwide.
