When we think of obesity, we may not necessarily associate it with cancer. But researchers have long suspected a link between certain cancers and weight.
These include endometrial cancer, ovarian cancer, colon cancer, liver cancer, pancreatic cancer, and postmenopausal breast cancer, which together account for 15 to 20 of all cancer deaths in the United States. %.
Cancer risk increases with obesity
More than one-third of adults in the United States are considered obese, with a body mass index (BMI) of 30 or higher. BMI is a measure of body fat based on weight and height. The number of severely obese people with a BMI of 40 or higher is increasing significantly. According to a study published in the New England Journal of Medicine, increasing your BMI by even 5 points increases your risk of cancer by 10%.
People who are obese are twice as likely to develop cancer than people who are a healthy weight. For example, if your BMI exceeds 40, your risk of endometrial cancer increases seven times.
The greater risk of cancer appears to be due to excess weight in the form of fat. Obesity increases fat cells in the body. As the number of these fat cells increases, the release of hormones in the body changes. These changes tend to increase pro-inflammatory hormones and estrogen. This chronic inflammatory state causes damage to cells and the DNA within them and can increase the risk of certain types of cancer.
Researchers are studying the role body fat plays in chronic inflammation. Additionally, hormones such as estrogen and insulin resistance can lead to chronic metabolic diseases such as diabetes. The Centers for Disease Control and Prevention estimates that by 2050, one in three adults will have diabetes and its associated complications.
Link between bariatric surgery and cancer risk reduction
Researchers believe that reducing inflammatory fat cells may reduce cancer risk, but more research is needed. And it's still unclear how much nonsurgical or intentional weight loss improves cancer risk.
However, for those who have lost weight through lifestyle changes, the challenge is to maintain it. The body has many complex neurohormonal systems to avoid starvation, making it difficult to maintain weight loss.
Currently, bariatric surgery or metabolic surgery is the most effective treatment for obesity, even compared to pharmacotherapy and intensive lifestyle therapy. After surgery, you typically lose 50 to 70 percent of your excess weight, or 25 to 35 percent of your total body weight, and this condition is often maintained for many years.
Continuation of research
Several large studies have been conducted to investigate the association between weight loss from bariatric surgery and reduced cancer risk.
A 2019 article in the Annals of Surgery compared more than 22,000 people who underwent bariatric surgery to 66,000 who did not. Study participants were matched by gender, age, study site, BMI, and other factors. Statistical models were used to examine the incidence of cancer up to 10 years after bariatric surgery compared to participants who did not undergo surgery.
Those who underwent bariatric surgery had a 33% lower risk of developing any type of cancer during follow-up compared to those who did not undergo bariatric surgery. The results were even stronger when limited to obesity-related cancers.
A 2022 study published in the Journal of the American Medical Association followed 30,000 people with a BMI of 35 or higher. Participants were divided into two groups and matched by factors such as age and gender. One group of approximately 5,000 patients had undergone bariatric surgery. Another group of just over 25,000 patients did not undergo surgery. Median follow-up was approximately 6 years.
Follow-up studies have shown that bariatric surgery is associated with a significant reduction in the risk of obesity-related and other cancers. The researchers also showed that patients who underwent bariatric surgery had fewer cancer-related deaths than those who did not undergo surgery.
Researchers continue to investigate why and how bariatric surgery reduces the risk of cancer and diabetes, and further studies are needed to confirm these results. However, for patients suffering from obesity, there is hope that bariatric surgery may reduce the risk of metabolic diseases such as diabetes and, in some cases, cancer.
If you're considering bariatric surgery, this new evidence about its effectiveness and benefits may help you decide. This is another topic to discuss with your health care provider or bariatric surgery team.
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Dr. Maria Linnas is a bariatric surgeon in Eau Claire, Wisconsin.
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