A new report warns about the role of obesity in cancer. As many as 40 percent of all cancers are related to obesity, according to the new research, which suggests that these cancers would be preventable if weight was kept under control.
The report, entitled Vital Signs, was compiled by researchers from the Centers for Disease Control and Prevention (CDC) in collaboration with researchers from the National Cancer Institute.
C. Brooke Steele, of CDC's Division of Cancer Prevention and Control, is the first and corresponding author of the report.
The findings are particularly important given the alarming statistics on obesity in the United States. Between 2013 and 2014, the CDC note, as many as 2 in 3 adults were deemed overweight or obese.
Being overweight is defined as having a body mass index (BMI) between 25 and 29.9 kilograms per square meter, and obesity is defined as having a BMI of 30 kilograms per square meter and over.
Studying obesity and cancer diagnoses
Steele and colleagues examined cancer incidence rates using data from the U.S. Cancer Statistics 2014, as well as looking at trends between 2005 and 2014.
More specifically, the researchers looked at the 13 types of cancer that have traditionally been associated with being overweight and having obesity. These include a type of esophageal cancer called esophageal adenocarcinoma, postmenopausal breast cancer, colorectal cancer, endometrial cancer, gallbladder cancer, and gastric cardia cancer.
Additionally, the researchers looked at cancer of the kidney, liver, and thyroid, as well as ovarian and pancreatic cancer. The report also examined meningioma, which is a slow-progressing type of brain tumor, and multiple myeloma.
Steele and team grouped and analyzed the data by sex, age, ethnicity, geographic area, and the site where the cancer appeared.
The researchers analyzed trends both with and without the incidence of colorectal cancer. As they explain, this is due to the fact that screening for colorectal cancer can reduce incidence because the procedure often detects the colorectal polyps before they become malignant.
Around 630,000 obesity-related cancers
Overall, in 2014, approximately 630,000 people in the U.S. received a diagnosis of one of the aforementioned cancers, which represents a staggering 40 percent of all diagnosed cancers.
The incidence rate was particularly high among adults aged 50 and above. In fact, 2 in 3 of these cancers occurred in those aged between 50 and 74.
Gender-wise, more cancers were linked with obesity in women than in men. And more specifically, 55 percent of the cancers affecting women and 24 percent of those affecting men were related to obesity.
Regarding obesity-associated cancers, these rose by 7 percent between 2005 and 2014. By comparison, the incidence of cancers not associated with obesity declined by 13 percent during that time. Colorectal cancer also decreased by 23 percent, most likely due to screening practices.
"The burden of overweight- and obesity-related cancer is high in the United States," say the authors.
They add that it "might be reduced through efforts to prevent and control overweight and obesity," and they conclude that "[c]omprehensive cancer control strategies, including use of evidence-based interventions to promote healthy weight, could help decrease the incidence of these cancers in the United States."
Dr. Brenda Fitzgerald, who is the director of the CDC, comments on the findings.
"A majority of American adults weigh more than recommended - and being overweight or obese puts people at higher risk for a number of cancers - so these findings are a cause for concern [...] By getting to and keeping a healthy weight, we all can play a role in cancer prevention."
Dr. Brenda Fitzgerald
The CDC have also released a video for public awareness, which you can watch below.