There’s no denying that America has a weight problem, and it’s impacting our overall health. Medical science has conclusively linked being overweight or obese to a range of chronic diseases, from diabetes and cardiovascular disease to osteoarthritis, liver disease and several types of cancer. The Centers for Disease Control and Prevention defines being overweight or obese as “weight that is higher than what is considered as a healthy weight for a given height.” And it appears the more excess weight a person carries, the worse the potential health consequences.
Among these concerns is a risk for developing breast cancer. The connection between having a high body mass index (a height-to-weight ratio that’s used as the standard measure to assess weight-associated health risks that you can calculate for yourself on the National Institutes of Health website) and breast cancer is well established and thought to be related to metabolism, inflammation and hormones. Perhaps not coincidentally, these factors can also contribute to the development of diabetes. So a question has arisen: Does having diabetes elevate a person’s risk for developing breast cancer?
[See: 7 Innovations in Cancer Therapy.]
The answer isn’t completely settled yet, but it does appear that having diabetes could put you at an increased risk of developing breast cancer, says Dr. Sagar Sardesai, assistant professor of medicine at the Stefanie Spielman Comprehensive Breast Center at The Ohio State University Wexner Medical Center. For starters, he cites a meta-analysis published in the British Journal of Cancer in 2012 that found “the risk of breast cancer in women with Type 2 diabetes is increased by 27 percent, a figure that decreased to 16 percent after adjustment for BMI,” meaning the researchers had controlled for overweight and obesity. This elevated risk was seen in Type 2 diabetes and among post-menopausal women. (Type 2 diabetes is the more common form of the disease. It typically occurs in adults and has been linked to obesity, a lack of physical activity and poor diet.)
But there may be more to the question than just whether a patient has diabetes. It may go deeper, back to the shared risk factor of obesity or to insulin resistance, the precursor state to Type 2 diabetes, Sardesai says. “There’s an association between diabetes, obesity and insulin resistance that is really responsible for this association that we’re seeing here with diabetes and breast cancer,” he says.
“Typically, when you think about Type 2 diabetes, that comes on in a person’s 50s and 60s, so among post-menopausal women. It’s often preceded by a phase when your body is becoming resistant to insulin. That may be because of obesity. That may be because of genetics or physical inactivity. These are risk factors for having insulin resistance,” which means the body isn’t generating enough insulin in the pancreas to cope with the levels of sugar in the blood. This insulin-resistant phase can last five to 10 years or more before the person is diagnosed with diabetes, and Sardesai says this period of insulin resistance could be part of the increased risk for breast cancer.
“The short answer is, based on all the data, there has been an association made between diabetes and post-menopausal breast cancer, and it seems to be linked to this insulin resistance that precedes the onset of diabetes.” He points again back to obesity as a major cause of both diseases.
Gertraud Maskarinec, a preventive medicine physician and nutritional epidemiologist at the University of Hawaii Cancer Center, adds that the possible connection between diabetes and breast cancer may be related not just to the age of the patient but also the severity and duration of the diabetes. “The potential I see is for women who’ve had diabetes for a very long time and the serious kind of diabetes.” Although some cases of Type 2 diabetes can be controlled through diet, exercise and oral medications, the more severe and often later-stages of the disease typically require insulin injections, which may happen up to several times daily. As the disease progresses, that can lead to additional health problems over time. “I think then their metabolic system might be in a certain state that has an additional risk for breast cancer.”
[See: Breast Pain? Stop Worrying About Cancer.]
Sardesai says beyond just breast cancer, other studies have looked for a connection between diabetes and other forms of cancer and have found that “irrespective of where the site was — gastrointestinal, breast, uterine or another cancer — diabetes was associated with a 13 percent increase in all cancers.” Having diabetes also seems to increase all-cause mortality, meaning the patient is more likely to die sooner, not necessarily from the cancer, but from any cause of death.
The connection between breast cancer and diabetes could also be a two-way street: Breast cancer survivors may also be at an elevated risk of developing diabetes after their treatment. “We don’t know the mechanisms, but this has been seen in a recent Canadian study,” Sardesai says. “Women who were breast cancer survivors who’d had chemotherapy had a higher risk of developing diabetes after their treatment.”
One potential bright spot in the discussion of the intersection of diabetes and breast cancer is some promising results from studies looking at the prognosis of diabetic breast cancer patients taking metformin, a common medication used to control blood sugar. “Women who were diabetic and taking metformin had a 25 percent lesser risk of developing breast cancer,” than nondiabetic women who weren’t taking the drug, Sardesai says. It’s not certain exactly why, but it could be that controlling blood sugars reduces risk for developing breast cancer, so “metformin is being actively investigated in reducing cancer risk,” he says.
But you can have good results without reaching for a pill, too. “If you combine physical activity and nutrition and are able to get your weight under control, it reduces your risk of breast cancer by 15 percent or so, which is huge,” he says.
Maskarinec agrees that “the intervention is obvious: more physical activity and less body weight.” Achieving both of these aims can help prevent your risk for a whole host of diseases, not just breast cancer or diabetes.
[See: The 10 Best Diets for Healthy Eating.]
Still, knowing what and how much to eat can be tricky for some people, so Maskarinec says the key is to control your weight. “It’s not just eating right, it’s eating less that is the secret. People with concern for diabetes — maybe the number one thing is [increasing] physical activity, and then eating less. Eating right may be important, too — if you eat the wrong stuff, you might be more likely to be obese. But at the end, being obese from healthy foods is still a bad idea. It’s not that difficult to be obese from healthy foods, you just have to eat more of them.”
So be mindful with that forkful and make sure you’re getting as much exercise as you can to help lower your risk of developing both diabetes and breast cancer.
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Is There a Connection Between Diabetes and Breast Cancer? originally appeared on usnews.com
