Obesity is a condition in which the body has an unhealthy amount and poor distribution of body fat. Obesity can affect every aspect of everyday life for anyone from their daily diet, activity levels, medical issues, and numerous challenges due to their physical body mass and size. According to a study conducted by the Centers for Disease Control in 2014, almost seventy-percent of United States adults over the age of twenty were overweight or obese, and one-third of those people were morbidly obese. These numbers continue to rise across the country and globe, in every age group, and within every culture, with more diseases and long-term illnesses being linked to obesity than ever before.
How does obesity increase my risk of cancer?
There are several aspects and side effects of being obese or severely overweight that can increase the risk of developing a number of cancers. These circumstances have all contributed to higher risk levels:
- Obese people often have chronic low-level inflammation, which can cause DNA damage that leads to cancer. Overweight and obese individuals are more likely than normal-weight individuals to have conditions or disorders that are linked to or that cause chronic local inflammation and that are risk factors for certain cancers. For example, chronic local inflammation induced by gastroesophageal reflux disease or Barrett esophagus is a likely cause of esophageal adenocarcinoma. Obesity is a risk factor for gallstones, a condition characterized by chronic gallbladder inflammation, and a history of gallstones is a strong risk factor for gallbladder cancer. Chronic ulcerative colitis, which is a chronic inflammatory condition, and hepatitis- which is a disease of the liver causing inflammation, are risk factors for different types of liver cancer.
- Fat tissue, or adipose tissue, produces excess amounts of estrogen, high levels of which have been associated with increased risks of breast, endometrial, ovarian, and some other cancers.
- Obese people often have increased blood levels of insulin and insulin-like growth factor-1 (IGF-1). This condition, known as hyperinsulinemia or insulin resistance, precedes the development of type 2 diabetes. High levels of insulin and IGF-1 may promote the development of colon, kidney, prostate, and endometrial cancers.
- Fat cells produce adipokines, hormones that may stimulate or inhibit cell growth. For example, the level of an adipokine called leptin, which seems to promote cell proliferation, in the blood increases with increasing body fat. And another adipokine, adiponectin—which is less abundant in obese people than in those of normal weight—may have antiproliferative effects.
- Fat cells may also have direct and indirect effects on other cell growth regulators, including mammalian target of rapamycin and AMP-activated protein kinase.
Other possible reasons by which obesity could affect cancer risk include changes in the mechanical properties of the scaffolding that surrounds breast cells and altered immune responses, effects on the nuclear factor kappa beta system, and oxidative stress.
Which types of cancers are most often affected by obesity?
All information coming in on statistics and record keeping on cancer and obesity come from observational studies. Sometimes this data can be difficult to interpret and cannot correlate a direct link that obesity in itself causes cancer. This is because the overall body reaction of having and getting treatment for cancer as an obese individual is much different from that of a person who is slender. Despite the limitations of these observational study designs, the consistent evidence collected tells us that higher amounts of body fat are indeed associated with an increased risk for certain types of cancer. Those types are:
- Breast cancer: Many studies have shown that, in postmenopausal women, a higher BMI is associated with a modest increase in the risk of breast cancer. For example, a five-unit increase in BMI is associated with a twelve-percent increase in risk. Among postmenopausal women, those who were obese have a twenty-to-forty percent increase in the risk of developing breast cancer compared with normal-weight women. The higher risks are seen mainly in women who have never used menopausal hormone therapy and for tumors that express hormone receptors. Obesity is also a risk factor for breast cancer in men.
In premenopausal women, by contrast, overweight and obesity have been found to be associated with a twenty-percent decreased risk of breast tumors that express hormone receptors.
- Ovarian cancer: Higher BMI is associated with a slight increase in the risk of ovarian cancer, particularly in women who have never used menopausal hormone therapy. For example, a five-unit increase in BMI is associated with a ten-percent increase in risk among women who have never used menopausal hormone therapy.
- Thyroid cancer: Higher BMI, specifically a five-unit increase in BMI, is associated with a slight increase in the risk of thyroid cancer.
- Meningioma: The risk of this slow-growing brain tumor that arises in the membranes surrounding the brain and the spinal cord is increased by about fifty-percent in people who are obese and about twenty-percent in people who are overweight.
- Pancreatic cancer: People who are overweight or obese are about one-and-a-half times as likely to develop pancreatic cancer as normal-weight people.
- Colorectal cancer: People who are obese are slightly more likely to develop colorectal cancer than normal-weight people. A higher BMI is associated with increased risks of colon and rectal cancers in both men and in women, but the increases are higher in men than in women.
- Gallbladder cancer: Compared with normal-weight people, people who are overweight have a slight increase in the risk of gallbladder cancer, and people who are obese have a sixty-percent increase in the risk of gallbladder cancer. The risk increase is greater in women than in men.
- Esophageal adenocarcinoma: People who are overweight or obese are about twice as likely as normal-weight people to develop a type of esophageal cancer called esophageal adenocarcinoma, and people who are extremely obese are more than four times as likely.
- Gastric cardia cancer: People who are obese are nearly twice as likely as normal-weight people to develop cancer in the upper part of the stomach, that is, the part that is closest to the esophagus.
- Liver cancer: People who are overweight or obese are up to twice as likely as normal-weight people to develop liver cancer. The association between overweight and obesity and liver cancer is stronger in men than in women.
- Kidney cancer: People who are overweight or obese are nearly twice as likely as normal-weight people to develop renal cell cancer, the most common form of kidney cancer. The association of renal cell cancer with obesity is independent of its association with high blood pressure, a known risk factor for kidney cancer.
- Multiple myeloma: Compared with normal-weight individuals, overweight and obese individuals have a slight increase in the risk of developing multiple myeloma.
- Endometrial cancer: Obese and overweight women are two to about four times as likely as normal-weight women to develop endometrial cancer, which is a cancer of the lining of the uterus, and extremely obese women are about seven times as likely to develop the more common of the two main types of this cancer. The risk of endometrial cancer increases with increasing weight gain in adulthood, particularly among women who have never used menopausal hormone therapy.
Does obesity affect survivorship?
Studies done to check on the effects of obesity and survivorship after cancer and treatment focus mainly on those diagnosed with prostate, colorectal and breast cancers. These studies show that without a doubt, obesity can worsen many aspects of survivorship like overall prognosis, quality of life, intimacy, sexual ability, cancer recurrence, and cancer progression.
For an example, obesity is directly associated with lymphedema. Lymphedema is the collection of fluid under certain parts of the body, linked to a malfunctioning lymphatic system. Other studies done specifically on breast cancer patients showed with weight loss after treatment, certain biomarkers that also show signs of cancer had diminished.
If you are obese or severely over-weight, consider taking steps to save and take control of your own life by contacting your doctor and beginning a beneficial treatment plan immediately. Obesity is linked to the worsening and development of many other illnesses than cancer, and numerous severe complications and medical issues all throughout the body. While reaching out to get help for your weight may be embarrassing, there are many people going through the same bariatric surgeries and diets that you may face. You are not alone in this battle, and you can reclaim your weight!
Always seek your doctor’s advice before beginning any new diet or eating plan while on other medications or in treatment for cancer.
ACS- https://www.cancer.org/cancer/cancer-causes/diet-physical-activity/body-weight-and-cancer-risk/effects.html Reclaiming Intimacy