Breast cancer and obesity

Category: Blog

So much evidence has been produced to make a clear link between obesity and breast cancer. Now new evidence also links breast cancer recurrence in obese survivors. Here is a review of the new studies:

Doctors in London writing in the medical journal Current treatment options in oncology had this to say:

“Obesity not only is an independent risk factor of postmenopausal breast cancer, and in particular estrogen receptor-positive/progesterone receptor-positive breast cancer, it is also a prognostic factor of the disease. . . .” (explanatory note: breast cancer that is estrogen receptor-positive means that estrogen is sending signals to the breast cancer cells to grow. Progesterone receptor-positive breast cancer means that the hormone progesterone is sending signals to the breast cancer cells to grow.)

“Substantial evidence has shown that obesity, as measured by body mass index is linked to breast cancer outcomes. All-cause and breast cancer-specific mortality risk increase for each BMI (Body Mass Index) unit increase in pre- and postmenopausal breast cancer survivors is estimated to range from 8 to 29 % . . .”

(Simply as breast cancer survivors gain weight the risks for recurrence is that much greater).

“Furthermore, the negative impact of abdominal obesity on breast cancer survival highlights the need of using fat distribution (waist circumference, waist-hip-ratio) as well as general obesity to evaluate prognosis in the clinical setting. . . . Oncologists should recommend their patients to be physically active and control body weight when the conditions of the patient allow it.”1

Cancer in the other breast, estrogen and obesity

Obesity as we have seen above is a factor for estrogen receptor-positive cancers. Researchers are showing obesity to be a factor in estrogen receptor-negative cancers. (Estrogen receptor-negative cancers cannot absorb estrogen – hence they are estrogen negative, this means that cancer treatments designed to block hormones will not be effective and chemotherapy and breast cancer surgery will be recommended).

A collaborating team of researchers including those from Stanford, New York, University, Sloan-Kettering,  and the University of Texas MD Anderson Cancer Center among others studied  the relationship between body mass index and the risk of contralateral (the other side) breast cancer. The same research teams had previously showed that obese postmenopausal women with estrogen receptor (ER)-negative breast cancer have a fivefold higher risk of contralateral breast cancer compared with normal weight women.

In the new findings researchers confirmed that women with an estrogen receptor-negative first primary cancer who are obese at the first diagnosis or who experience a large weight gain afterward should be watched with “heightened surveillance,” for risk of secondary cancer from obesity.


1. Chan DS, Norat T. Obesity and breast cancer: not only a risk factor of the disease. Curr Treat Options Oncol. 2015 May;16(5):22.
2. Brooks JD, John EM, Mellemkjaer L, Lynch CF, Knight JA, Malone KE, Reiner AS, Bernstein L, Liang X, Shore RE, Stovall M; WECARE Study Collaborative Group., Bernstein JL. Body mass index, weight change, and risk of second primary breast cancer in the WECARE study: influence of estrogen receptor status of the first breast cancer. Cancer Med. 2016 Oct 3. doi: 10.1002/cam4.890.