You may be aware that obesity causes numerous chronic health problems, but did you know that obesity directly or indirectly causes cancer as well? Many researches have established a crystal-clear link between obesity and cancer. In this page, we would understand about obesity, cancer and the association between them.
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About obesity +
Obesity means excess accumulation of fat in the body, which increases the risk of many chronic health conditions. The body mass index (BMI) which is a simple estimate of body fat, helps to determine if an individual is obese. People with BMI of over 30kgs/m² are considered obese. Obesity can be associated with various health problems such as:
- Type 2 diabetes
- Cardiovascular complications (heart attack and stroke, among others)
- High cholesterol (hyperlipidemia)
- High blood pressure (hypertension)
- Heartburn/esophageal reflux
- Sleep apnea (obesity hypoventilation syndrome)
- Joint problems
- Gallstones
- Fatty liver disease and/or cirrhosis
- Cancers of the colon, gallbladder, breast, uterus, esophagus, prostate, cervix, or pancreas
- Reproductive disorders such as polycystic ovarian syndrome (PCOS)
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About cancer +
Cancer refers uncontrolled and abnormal growth and multiplication of cells in any part of the body. Cancers may affect the surrounding body tissues and cancer cells may spread to the different parts of the body.
In 2018, 18.1 million new cases of cancer and 9.6 million deaths associated with cancer were reported world-wide. Cancers of the lung, breast, and colorectum are the three common types of cancer leading to mortality. In women, breast cancer is the most common cause of death.
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Obesity and its relationship with cancer +
Excess fat basically changes the internal environment of the human body. This may affect the cells at the genetic level and can predispose to cancer. Obesity has been associated with the development of 13 types of cancers namely- multiple myeloma; esophageal cancer; brain cancer, postmenopausal breast cancer; thyroid cancers, gastrointestinal cancers( colon, gallbladder, stomach, liver, pancreas), renal cell cancer, and cancer of the ovaries, and uterus.
Mechanisms of obesity-associated cancer
The three plausible mechanisms that explain the relationship between obesity and cancer risk include:
- Insulin and growth factors: Excess fat causes insulin resistance in the body, which triggers the pancreas to produce more amount of insulin to compensate. Insulin resistance or increased insulin elevates the levels of growth factors, which encourages the cells to divide rapidly which may cause cancer.
- Inflammation: Fat cells release inflammatory chemicals like cytokines which encourages the cells to divide at a more rapid pace than they die off. This causes build-up of cells, which can lead to the development of cancer. This is one of the main theories which explain the relationship between obesity and cancer.
- Sex hormones: After menopause, excess fat can trigger the release more estrogen (female sex hormone), which makes the cells in the breast and womb to divide uncontrollably. This results in the development of post-menopausal breast cancer and uterine cancer.
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Prevention of obesity-associated cancer +
The only way to reduce the risk of cancer associated with obesity is to lose weight and stay healthy. Weight loss can be achieved by following simple life-style changes, such as:
- Avoid foods that are rich in saturated fats and calories.
- Eat fiber-rich foods, such as fruits, vegetables, nuts, fish oil, whole grains and avocado that helps in lowering the cholesterol in the body.
- Exercise daily for 30 minutes.
- Avoid consuming alcohol and stop smoking.
Increased waist-line (Abdominal fat) is mostly corelated cancer. So, people with excess abdominal fat should involve in the physical activities that mainly target the abdominal fat. Abdominal strengthening exercises can help in strengthening the abdominal muscles and also reduces fat.
Post-menopausal women should maintain healthy weight to prevent the risk of breast, uterus and ovarian cancer.
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Treatment for cancer in obese patients +
Obese patients are treated with lower doses of chemotherapy (medications used to treat cancer) than non-obese patients. The full dose of chemotherapy agents can result in toxicity in obese people, as the dosing of chemotherapy drugs is based on the assumption that metabolism is proportional to the body surface area.
Radiation therapy (using high-intensity radiations to kill cancer cells) also becomes difficult in obese patients due to the difficulty in passing the radiations over the targeted tumors.
During cancer surgery, most of the obese patients develops serious airway complications under general anesthesia. Obese patients also face a higher risk of complications after surgery including heart attack, nerve injury, and wound infection.
It is recommended for a person diagnosed with cancer to involve in weight loss programs while undergoing the treatment for cancer.
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Outlook +
Obesity has become the leading cause of cancer in most of the countries. Obesity associated cancers can be managed by reducing the weight. As women have the high risk of developing cancers than men, it is recommended to maintain a healthy weight to prevent the risk of cancers, mainly post-menopausal breast cancer and womb cancer.
References
https://www.ncbi.nlm.nih.gov/pubmed/27909899
http://clinchem.aaccjnls.org/content/64/1/154
https://www.wcrf.org/int/blog/articles/2017/03/how-does-obesity-cause-cancer-science-behind-warnings
https://www.ncbi.nlm.nih.gov/pubmed/28359241
http://theoncologist.alphamedpress.org/content/15/6/556.full
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