Overweight adolescents are twice as likely as their normal-weight peers to develop esophageal cancer later in life, a recent study shows.
The Israeli study also found that lower socioeconomic status as well as immigration from higher risk countries were important determinants of gastric cancer.
Young Israelis are obliged to undergo a medical examination when they are about 17-years-old to assess their suitability for military service. Dr. Zohar Levi, of the Rabin Medical Center, and his team used this data as the basis of their research.
They measured the body mass index (BMI) of 1 million Israeli adolescent males from 1967 to 2005. And by checking these figures against the country's cancer registry, they identified which of the participants later developed cancer.
This is a reliable record of reported cancers, as it has been mandatory for tumors to be reported here since 1982.
Participants were followed from 2.5 to almost 40 years, with an average follow-up of 18.8 years.
Linking youth obesity to cancers
The study points out that while adult obesity has been consistently linked with an increased risk of developing esopahgeal cancer, the link between youth obesity and this type of cancer had not been explored.
The researchers were surprised to find that events - particularly weight and socioeconomic status - up to the age of 17 had a tremendous impact upon cancer development later in life.
The research showed that adolescents who were overweight had a 2.1-fold increased risk of developing esophageal cancer. Adolescents who were of low socioeconomic status had a 2.2-fold increased risk of developing intestinal type gastric cancer.
Those who had 9 years or less of education had a 1.9-fold increased risk of developing this type of cancer. Also, immigrants born in Asian and former USSR countries had higher risks of developing gastric cancer (3-fold and 2.28-fold increased risks, respectively).
In the current study, immigration occurred up to the age of 19, but interestingly, the impact on developing subsequent cancer lasted. The researchers note that these disparities could be explained by the role of diet (most notably salt intake) and tobacco use, both of which are associated with the development of gastric cancer.
Dr. Levi says:
"Adolescents who are overweight and obese are prone to esophageal cancer, probably due to reflux that they have throughout their life. Also, a lower socioeconomic position as a child has a lot of impact upon incidence of gastric cancer as an adult."
Obesity rates on the rise
According to the National Cancer Institute figures from a 2007-2008 survey, 68% of American adults aged 20 or older are overweight or obese. This figure is similarly alarming for children - with 17% of children and young people aged between 2 and 19 estimated as being obese.
And these figures are increasing.
Dr. Levi points out:
"We look at obesity as dangerous from cardiovascular aspects at ages 40 and over, but here we can see that it has effects much earlier."
Researchers note that the current study lacked information about the participants diet, alcohol consumption and tobacco use.
Dr. Levi's team also says that it is not clear whether losing weight later in life or gaining higher socioeconomic status might reduce the risks observed in this study.