Obese women at increased risk of developing cancer
Obese women are over 40 percent more likely to develop certain cancers than women of a healthy weight, according to new estimates from Cancer Research UK.
Obesity is defined as having a body mass index (BMI) of 30 or higher. In the United States, more than a third of adults and nearly a fifth of children and adolescents are affected by obesity.
Seven types of cancers have previously been linked to weight: breast (postmenopausal), bowel, pancreas, esophageal, uterus (endometrium), kidney and gallbladder.
A statistical information team from Cancer Research UK, the world's largest independent cancer research charity, assessed data on lifetime cancer risk in the UK population, data on excess weight and obesity among UK women, as well as the results of a 2011 study published in the British Journal of Cancer that analyzed the link between being overweight or obese and cancer development to reach their estimates.
The team calculated that women who are obese are 41 percent more likely to develop one of the seven cancers than women who are a healthy weight. In a group of 1,000 women, the team estimated that 274 would develop one of the cancers, compared to 194 women who were a healthy weight.
The risks of cancer in obese women compared to healthy weight women were:
Esophageal - 133 percent
Uterus (endometrium) - 131 percent
Gallbladder - 100 percent
Kidney - 78 percent
Bowel - 32 percent
Pancreas - 31 percent
Breast (postmenopausal) - 25 percent
According to the National Cancer Institute, there are several possibilities to explain the association between obesity and the increased risk of certain cancers. One possibility is that fat tissue produces excess amounts of estrogen, high levels of which have been linked with the risk of breast and endometrial cancer. Another possibility is that fat cells produce hormones called adipokines that may stimulate or inhibit cell growth.
"We know that our cancer risk depends on a combination of our genes, our environment and other aspects of our lives, many of which we can control - helping people understand how they can reduce their risk of developing cancer in the first place remains crucial in tackling the disease," said Dr. Julie Sharp, head of health information at Cancer Research UK.
"Lifestyle changes - like not smoking, keeping a healthy weight, eating a healthy diet and cutting back on alcohol - are the big opportunities for us all to personally reduce our cancer risk. Making these changes is not a guarantee against cancer, but it stacks the odds in our favor."
Previous studies have found that obesity increases the risk of the most common type of postmenopausal breast cancer in African-American and Hispanic women.
A 2014 study conducted by researchers from Tel Aviv University suggested that obesity could be a major contributor to Crohn's disease, multiple sclerosis, and other autoimmune diseases, including lupus and celiac disease. The researchers found that obesity creates a "pro-inflammatory" environment that can trigger the diseases and hinder treatment.