Teenage Obesity Increases The Risk For Cancer In Adulthood

Previous research indicated a higher risk for cancer in men with lower aerobic fitness levels during compulsory conscription for military service at the age of 18, and the risk was independent of whether these men were obese/overweight at the time. These 2 new studies go deeper, focusing on BMI as a factor, revealing that having a high BMI at 18 is associated with an even greater risk, surpassing the impact of poor fitness level at the same age.

The team identified a correlation between having a high BMI at 18 and an increased risk of 17 different types of cancer, which included: lung cancer, head/neck cancer, brain cancer, thyroid cancer, esophageal cancer, stomach cancer, liver cancer, pancreatic cancer, colon cancer, rectal cancer, bladder cancer, kidney cancer, leukemia, myeloma, malignant melanoma, and lymphoma (both Hodgkins’s and non-Hodgkin’s). 

Several types of these cancers were already at a heightened risk of development at a BMI of 20-22.4, within the usually used range of normal weight of 18-24.9, and this included head/neck cancer, esophagus cancer, stomach cancer, pancreas cancer, liver cancer, kidney cancer, malignant melanoma, and non-Hodgkin’s lymphoma. 

“This suggests that the current definition of normal weight may be applicable primarily for older adults, while an optimal weight as a young adult is likely to be in a lower range. Our research group has drawn similar conclusions regarding BMI in early adulthood and later cardiovascular disease,” says Maria Åberg, professor of family medicine at Sahlgrenska Academy at the University of Gothenburg and senior author.

According to the researchers, the link with a high BMI was the strongest for abdominal cancers, with a higher risk for obese men at enrolment, and an unhealthy weight appeared to explain about 15-25% of cases of these cancers in Sweden today. However, prostate cancer was more common among those who were not overweight or obese at the time of enlistment.

The team suggests that in three decades there will be an increase in the proportion of cancer cases linked to being overweight or obese during youth, calculated based on obesity and overweight in today’s 18-year-old men in Sweden. They estimate that for stomach cancer the proportion will increase to 32% and esophagus cancer will increase to 37%. Additionally, based on the current prevalence of youth overweight/obesity in America there will be more than 1 in 2 cases of these two cancers which could be linked to a high BMI during teenage years in thirty years. 

“Overweight and obesity at a young age seems to increase the risk of developing cancer, and we see links between unhealthy weight and cancer in almost every organ. Given the alarming trend of obesity in childhood and adolescence, this study reinforces the need to deploy strong resources to reverse this trend,” says Aron Onerup a postdoc at Sahlgrenska Academy at the University of Gothenburg, and St. Jude Children's Research Hospital in Memphis, USA, and first author of the studies.

Diving even deeper the team also looked at the mortality rates after cancer diagnosis in this same group. Based on their analysis, of the 1,489,115 included in the study who enlisted in Sweden between 1968- 2005, during the follow-up period 84,621 cases of cancer were diagnosed. Those who were obese/overweight were found to be 2-3 times more likely to die within 5 years of being diagnosed with skin cancer, Hodgkin’s lymphoma, thyroid cancer, bladder cancer, and prostate cancer. Men who were obese/overweight were also 1.4-2 times more likely to die from cancers of the head/neck, kidneys, and rectum.