Is Being Obese a Warning Sign for Breast Cancer?


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Is Being Obese a Warning Sign for Breast Cancer?

Obesity has long been known for causing numerous adverse effects on health. It is linked to enormous problems and considered a risk factor of many diseases.

Apart from its usual destructive effects on general well-being, it has a very complicated, yet interesting relationship with breast cancer incidence. It is believed that obesity increases the chances of breast cancer in postmenopausal women. Conversely, in premenopausal women, obesity decreases breast cancer risk.

Why Estrogen is a Crucial Hormone?

Before initiating the discussion of obesity’s complicated effects, let me tell you what estrogen is? It is a female sex hormone that is necessary for the development and maintenance of female characteristics of the body. This includes normal breast development as well.

Normal estrogen levels differ throughout life, peaking at puberty. Then throughout premenopausal time, that is the time span when the women have her menses, estrogen levels rise in first fifteen days while they decrease in the last fifteen days.

After the cessation of menses, that is the postmenopausal time, estrogen production virtually stops. Pregnancy also causes estrogen levels to change. The important concept to grab for now is that the optimal level of estrogen hormone is essential for the development and growth of breast tissue, but too much estrogen in the body can increase the risk of cancer. This is because high estrogen levels cause rapid breast growth which increases the chances of abnormal growth.

What Postmenopausal Women Need To Know:

Obesity is a risk factor for breast cancer in postmenopausal women (after termination of periods). The time span of weight gain is very important for a positive association of obesity with cancer. It is believed that women who gain weight in teen ages or early adulthood are more prone to develop cancer instead of the women who gain weight in later adulthood. In premenopausal time (before termination of periods), obesity is in fact considered to lower the risk of developing cancer. This will be explained later. For now, let’s discuss how obesity increases the chances of cancer in postmenopausal women.

  • Conversion Of Fats To Estrogen:

In obese people, there is an accumulation of adipose tissues (fats). These fats, in postmenopausal women, convert to estrogen. As in postmenopausal women, breasts are already developed, lactation is not required, and the uterus can’t conceive. There is no need of estrogen. Synthesis of this little estrogen can therefore increase the chances of cancer by its effect on the breasts (Appleby PN, Reeves GK, et al, 2011).

  • Influence On Other Hormones:

Obesity causes increased production of insulin and sex hormones. Additionally, it decreases the sex hormone binding globulin. As a hormone exerts its effect only when it is in free form and binding to globulin is done only to transport it to favorable sites. So less sex hormone binding globulin increases the free form of estrogen, thus increasing the action of estrogen. This also causes an increased risk of cancer.

  • Insulin Like Growth Factors:

Obesity leads to insulin resistance diabetes i.e. diabetes type II. In this type of diabetes, insulin is present in normal quantities and sometimes even higher, but the action of insulin is impaired.

Type II diabetes increases the production of IGF 1 (insulin-like growth factors). As the name indicates, these factors play important role in the growth in childhood and exerts anabolic effects throughout adulthood. High levels of circulating IGF increases the risk of cancer (Michels KB, Solomon CG, Hu FB, et al, 2003)

  • Increased Inflammation:

Obesity causes inflammation in body, that directly and indirectly increases the chances of cancer in postmenopausal women. The reason why inflammation increases the risk of cancer is by the production of cytokines and other factors. Moreover, inflammation also influences immunity against these types of cancer.

Obesity, Cancer Risk And Premenopausal Women:

Here comes the most interesting impact of obesity in premenopausal women. Generally, it is believed that obesity has a favorable association with cancer risk in premenopausal women. In fact, obesity decreases the chances of cancer (Int J Cancer, 2011).

The proposed mechanism for this advantageous link is through the influence of estrogen. The body already makes sufficient amounts of estrogen before menopause that is essential for the body requirements. However, as obesity impairs the synthesis of estrogen hormone, it can act as a countercheck on the overproduction of this hormone. Regardless, obesity even before menopause, should be discouraged as it has other severe adverse effects on health, that outweigh this positive association.

Weight Gain After Cancer Can Cause Further Problems:

Being obese at the time of diagnosis, increases the risk of other diseases linked with obesity like diabetes, osteoarthritis, cardiovascular diseases, back pain, etc. This risk is further elevated owing to the treatment of cancer. Generally, weight gain after the treatment of cancer is seen in many patients. This is due to decreased metabolism as a consequence of treatment regimens (J Clin Oncol, Jan, 1999).

Another reason causing obesity, in cancer survivors, is the reduction in physical activity post-surgery. Though, the newer chemotherapy treatments have overcome this adverse effect on the survivors. Whatever the cause may be, for the contribution of obesity, it negatively impacts general health and in fact many women have further complications of heart disease associated with breast cancer (J Clin Oncol, Nov 1, 2007). Weight loss following a diagnosis is greatly related to better prognosis and increased survival rates in obese women.

Complications Of Surgery Due To Obesity:

Obesity not only increases the chances of breast cancer, but also causes complications in the surgery. Surgery is the mainstay in the treatment of cancer, either as initial treatment or after neoadjuvant therapy. Obesity does not generally pose threats on minor surgeries. However, since 35-55% women undergo reconstructive surgery, obesity is a major concern as it results in poor surgical outcomes (Senate, State of New York, March 4, 2010). Obesity also causes problems in major surgeries like mastectomy and axillary dissection, so it should be addressed.

Weight Control Rehabilitation:

Weight loss after menopause is linked directly in decreasing the chances of cancer. In weight control management, there are three factors that are generally addressed as a triangle. They include exercise, diet, and also emotional management.

Exercise is considered to attenuate the factors or physiological responses of the body that increase the incidence of cancer and mortality rate caused by associated diseases, specifically cardiovascular problems (related to heart).

Exercise also burns extra calories that are not required by the body and actually cause obesity. Likewise, a diet is supposed to be nutrient rich, but should not contain excessive carbohydrates and fats. Emotional therapy is another key component in weight control rehabilitation.


Obesity is a hallmark of general health related adverse effects and also the cause of many serious diseases. In premenopausal women, obesity decreases the risk of cancer.

However, in postmenopausal women, there is strong evidence that relates obesity as a risk factor for cancer. Obesity not only increases the chances of cancer, but also makes the cancer prognosis worse and causes further complications in its treatment. Therefore, weight should be controlled by doing exercise, having proper diet and managing emotional health.


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