The fight against cancer and its relationship to obesity
According to a study, published in the March issue journal “Cancer”, several cancers that have been linked to obesity and a sedentary lifestyle, rose every year from 1999 through 2008. While the percentage of obesity-related colorectal cancer declined 2.6% yearly between 1999 and 2008, thanks to the widespread early screening, other common obesity-related cancers such as breast and endometrial (cancer of the lining of the uterus), as well as less common ones, such as pancreatic cancer have continued to climb as much high as 40 percent particularly for endometrial cancer.
If you have followed the latest news reports with the 2030 obesity projections in the US, it is not so shocking that the increasing trend in obesity will also lead to about 500,000 additional cases of cancer in the United States by 2030.
Let’s take a closer look at the possible mechanisms that have been suggested to explain the association of obesity with increased risk of certain cancer.
1. Fat tissue produces excess amounts of estrogen which have been associated with the risk of breast, endometrial, and some other cancers.
2.Obese people often have increased levels of insulin in their blood which may promote the development of certain tumors.
3. Fat cells produce hormones, called adipokines, that may stimulate or inhibit cell growth.
4. Obese people often have chronic low-level, or “subacute,” inflammation, also called oxidative stress, which has been associated with increased cancer risk.
Many studies have shown that weight gain during adult life, most often from about age 18 to between the ages of 50 and 60, has been consistently associated with risk of breast cancer after menopause.
The increased risk of postmenopausal breast cancer is thought to be due to increased levels of estrogen in obese women. After menopause, when the ovaries stop producing hormones, fat tissue becomes the most important source of estrogen. Because obese women have more fat tissue, their estrogen levels are higher, potentially leading to more rapid growth of estrogen-responsive breast tumors. Overweight and obese woman have been consistently at a two to four times higher risk in developing endometrial cancer than women of a normal weight, regardless of menopausal status. Many studies have also found that the risk of endometrial cancer increases with increasing weight gain in adulthood, particularly among women who have never used Menopausal HormoneTherapy.
Although it has not yet been determined why obesity is a risk factor for endometrial cancer, some evidence points to a role for diabetes II (another lifestyle related preventable disease), possibly in combination with low levels of physical activity. High levels of estrogen produced by fat tissue are also likely to play a role.
Among men, a higher BMI is strongly associated with increased risk of colorectal cancer. The distribution of body fat in the abdominal area (visceral adipose tissue) which can be measured by waist circumference, is showing the strongest association with colon cancer risk. One hypothesis to explain the cancer causing mechanism is that the high levels of insulin or insulin-related growth factors in obese people may promote colon cancer development.
I know that many of you highly educated and critical readers will ask the question if avoiding weight gain or losing weight will indeed decrease the risk of cancer?
Most data about whether losing weight or avoiding weight gain prevents cancer, come mainly from case controlled studies. While these studies are more difficult to interpret, many observational studies have shown that people who have a lower weight gain during adulthood or have successfully lost weight and kept it off, have a lower risk of colon cancer, breast cancer (after menopause) and endometrial cancer. The National Institute of Health has funded several controlled weight loss clinical trials which have demonstrated that losing weight reduces the risk of developing chronic diseases, such as diabetes, while improving their risk factors for cardiovascular disease.
However, these trials failed to prove that weight loss can prevent cancer. The reason is the effect of weight loss on the prevention of other chronic diseases would be demonstrated and the trial consequently stopped so the public could be informed of the benefits, before the effect on the prevention of cancer would become evident.
An important point needs to be made as a conclusion since fat tissue plays such an important role in the cancer developing mechanisms: Reducing your BMI (body mass index) and shedding excessive pounds through a mild fat-burning program has several benefits including reduction of several cancer risks and maintaining a healthy muscle mass which is crucial in increasing and/or maintaining an efficient, high metabolism and in avoiding sagging skin as a result of the weight loss. Such program should be guided by a certified professional and in collaboration with a supervising physician.
Please submit any questions,comments or future topics you like to be addressed to firstname.lastname@example.org. Dominique Kohlenberger has a masters degree in Physical Therapy; is a certified Health Coach, President of the Stroke Association of Florida and owner of Healthy Longevity on Longboat Key.