November 14, 2023, 10:34 am | Read time: 4 minutes
A Swedish research team has identified a dangerous link between overweight male adolescents and 17 types of cancer. Apparently, being overweight at a young age can significantly influence health status in later life.
According to the International Agency on Research on Cancer (IARC), being overweight in adulthood is an established risk factor for various types of cancer–does this also apply to adolescents? The link between being overweight or obese and the future risk of developing cancer has rarely been studied in teenagers. The global obesity epidemic does not spare children and adolescents: According to the World Health Organization (WHO), over 340 million children and adolescents aged 5 to 19 were overweight or obese in 2016. Scientists at the University of Gothenburg have now addressed this issue in a recent study.
Overview
How the research team proceeded
The Swedish scientists examined the extent to which the BMI (Body Mass Index) of young men affects the risk of various cancers.
To this end, they conducted a cohort study with a total of 1,489,115 male adolescents who were 18 years old at the start of the observation period. During the follow-up, which averaged 31 years, 78,217 participants developed cancer.
The risk of these 17 types of cancer is increased in teenagers
The BMI was associated with an increased risk of developing 17 types of cancer:
- Lung cancer
- Head and neck cancer
- Brain tumor
- Thyroid cancer
- Esophageal cancer
- Stomach cancer
- Pancreatic cancer
- Liver cancer
- Colon cancer
- Rectal cancer
- Prostate cancer
- Kidney cancer
- Bladder cancer
- Malignant melanoma
- Leukemia
- Myeloma
- Lymphomas, both Hodgkin and non-Hodgkin
Alarmingly, for some of these cancers, the risk was already increased when the teenagers’ BMI was in the normal weight range (BMI 18.5–24.9). For example, cancers of the esophagus and stomach showed an increased risk at a BMI of 20 to 22.4.
Prostate cancer deviates from the trend
A higher BMI was associated with a lower risk in the case of prostate cancer. Men who were neither overweight nor obese at age 18 were more likely to develop this type of cancer later in life.
According to the researchers, this deviation could be due to the fact that normal-weight men seek medical help for prostate health issues earlier, leading to quicker diagnoses.
Particularly, gastrointestinal cancers are favored by overweight
The link between a high BMI and the risk of gastrointestinal cancers was particularly pronounced. Teenagers who were obese had a 3.6-fold increased risk of esophageal cancer, and for stomach cancer, the factor was 3.1.
The study authors estimated that unhealthy weight could be responsible for 15 to 25 percent of current cancer cases of this type in Sweden.
Overweight increases the risk more than poor fitness
In a further study by the same research team, the influence of BMI, as well as that of cardiorespiratory fitness (endurance ability) of the participants on the risk of cancer was also examined.
The results showed that a higher BMI at age 18 was associated with an even greater risk of developing various cancers later in life than the effects of poor fitness.
This was particularly evident in thyroid cancer: While moderate fitness increased the cancer risk by only two percent, the risk increased by 22 percent due to overweight.
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Should BMI be assessed differently in teenagers?
Given that even normal-weight teenagers showed an increased risk for various cancers, the current definition of normal weight (BMI 18.5–24.9) might be more applicable to older adults. Conversely, it seems sensible for teenagers to maintain a weight in the lower BMI range.
More cancer cases in the future?
The findings provide insight into the potential consequences of the obesity epidemic among teenagers on the cancer landscape over the next three decades. The researchers predict a significant increase in cancer related to overweight and obesity in teenagers over the next 30 years: For example, the proportion of stomach cancer cases attributable to a high BMI could rise to 32 percent, and for esophageal cancer, it could reach 37 percent.
These figures underscore the authors’ call to reverse the dangerous trend of rising obesity rates.