Women beware: Obesity may increase your chances of developing breast cancer after menopause

A new study was published in JAMA Oncology, where the researchers analyzed data from the large, long-term Women’s Health Initiative study. It showed that women who were obese and overweight may have an increased risk than normal weight women to develop breast cancer. So think twice before munching on that third or fourth piece of cronut…

They looked at data on 67,142 post-menopausal women ages 50 to 79 years old from across the U.S., and followed them for an average of 13 years. Overall, there were 3,388 breast cancers detected by 2010.

The risk of cancer rises with the severity of obesity, where the most severe ones were 86 percent more likely to develop the most common form of breast cancer, and to be diagnosed with more advanced cancers. The study team grouped women by their body mass index (BMI), a measure of weight in relation to height. A BMI of less than 25 is considered normal, BMI between 25 and 30 is considered overweight and over 30 is obese. A BMI of 35 – the equivalent of a five-foot six-inch person weighing 216 pounds – or above is considered severely obese.

So what exactly is Breast Cancer?

Breast cancer is a disease in which malignant (cancer) cells form in the tissues of the breast. The damaged cells can invade surrounding tissue, but with early detection and treatment, most people continue a normal life. Some general facts about breast cancer you should know about:

– One in eight women will be diagnosed with breast cancer in their lifetime.
– Breast cancer is the most commonly diagnosed cancer in women.
– Breast cancer is the second leading cause of death among women.
– Each year it is estimated that over 220,000 women in the United States will be diagnosed with breast cancer and more than 40,000 will die.
– Although breast cancer in men is rare, an estimated 2,150 men will be diagnosed with breast cancer and approximately 410 will die
– The American Cancer Society estimated that in 2015, about 231,840 women will be diagnosed with invasive breast cancer and about 40,290 will die from the disease.
– The majority of breast cancer cases are “sporadic,” meaning there is no direct family history of the disease.
– The risk for developing breast cancer increases as a woman ages.
– Only 5% to 10% of breast cancers occur in women with a clearly defined genetic predisposition for the disease.


While other research have shown that there might be a connection between being overweight and breast cancer risk, it’s important to confirm that link, especially for something changeable like weight, “because that suggests women can do something about it,” said Marian Neuhouser, of the Cancer Prevention Program at the Fred Hutchinson Cancer Research Center in Seattle, who led the study.

About 5 percent of women in each weight group were diagnosed with an invasive breast cancer during the study period, but the risk of breast cancer increased with weight.Women with BMIs of 35 and up were about 56 percent more likely to be diagnosed with any type of invasive breast cancer during the study, compared to normal-weight women.

The analysis did reveal that normal-weight women who gained more than 5 percent of their starting weight over the study period had a 35 percent increased risk of breast cancer.But for women who were already overweight or obese, losing weight did not lower their increased breast cancer risk. “I think it’s important to note that this was not a weight loss trial,” Neuhouser said.

A research trial looking specifically at whether weight loss decreases breast cancer risk is needed to determine if it’s helpful for women, she said.

While more studies need to be conducted, Dr. Clifford Hudis told Reuters Health the new results are “a caution that once you’re overweight the damage may be done.”

Hudis, who co-wrote an editorial accompanying the new study, said research also needs to find out why increased weight may increase breast cancer risk so that solutions can be found.

“Unfortunately (overweight and obesity) is just a growing problem in Western countries,” said Hudis, who is chief of the Breast Medicine Service at Memorial Sloan Kettering Cancer Center in New York. “It’s a public health challenge.”


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