Obesity is known to increase the risk of cancer — but which kinds of cancer?
New research has found that the answer differs between men and women, and depends in part on where fat is located on the body.
“Doctors and scientists are aware that obesity increases cancer risk, but this connection is less well known to members of the public,” study author Mathias Rask-Andersen, a researcher at Uppsala University in Sweden, said in a news release.
To investigate the links between cancer and obesity among men and women, Rask-Andersen and other researchers turned to the UK Biobank, a biomedical database with genetic and health information from more than half a million participants across the UK.
The massive database also includes information on the distribution of fat in participants’ bodies and their cancer history, if any.
“An important aspect of obesity-associated disease risk is the distribution of fat in different compartments of the body,” said co-author Asa Johansson, also of Uppsala University.
“Fat stored in the abdomen is considered more pathogenic [disease-causing] compared to subcutaneous [below the skin] fat. In addition, the amount of fat stored in different compartments, as well as the rates of most cancers, is known to differ between females and males,” Johansson said.
Among their findings, the research team discovered that all cancer types except brain, cervical and testicular cancers are associated with obesity.
Men with obesity were found to be at higher risk for breast cancer, hepatocellular carcinoma and renal cell carcinoma. For women with obesity, the highest risks were associated with gallbladder cancer, endometrial cancer and esophageal adenocarcinoma.
And in terms of fat distribution versus fat accumulation, there were different effects between men and women for colorectal, esophageal and liver cancer.
For men, body fat accumulation was linked to a high risk for hepatocellular carcinoma, but the same link was not seen among women.
And unlike men, women with a larger proportion of fat stored in the abdomen had a higher risk of esophageal squamous cell carcinoma.
“We were surprised to see that there appeared to be a difference in the effect of obesity on cancer risk, not only between males and females, but also between post- and pre-menopausal females,” Johansson said.
“Most remarkable, obesity is only a risk factor for breast cancer after menopause, probably due to the change in estrogen production in association with menopause,” she added.
The authors noted that rising rates of obesity make their research especially timely.
“Given the rapidly increasing rates of obesity globally, obesity is now the fastest-growing risk factor for overall cancer risk,” Rask-Andersen said. “Measures to prevent and reduce the occurrence of obesity and being overweight are therefore highly motivated.
“However, it is important to consider that reducing weight does not eliminate the risk of cancer. There are still many individual risk factors that play a much larger impact on specific types of cancer, such as smoking for lung cancer and exposure to sun for skin cancer,” he added.