Obesity Increases Risk of 8 More Types of Cancer

Highlights

• Overweight and obesity increase the risk of 13 types of cancer
• Excess fat accumulation can cause overproduction of hormones that promote tumor growth
• Maintaining a healthy weight can reduce the risk of cancer

A healthy weight has been linked to reduced risk of chronic diseases and premature death. Now, a new study suggests that maintaining a healthy weight in adulthood can decrease the risk of developing eight more types of cancer. The rates of overweight and obesity are on the rise. Globally, more than 640 million adults and 110 million children are obese. One-third of the children and adults are obese in the United States.

Excess weight and obesity can cause thirteen types of cancer such as

• Stomach
• Liver
• Gallbladder
• Pancreatic
• Ovarian
• Meningioma (brain tumor)
• Thyroid
• Multiple myeloma

The current study was based on a review of more than 1,000 studies of excess weight and cancer risk analyzed by the World Health Organization's International Agency for Cancer on Research (IARC), France. In 2002, the researchers found evidence linked to excess weight or obesity to increased risk of cancers of the

• Colon
• Esophagus
• Kidney
• Breast
• Uterus

"The burden of cancer due to being overweight or obese is more extensive than what has been assumed. Many of the newly identified cancers linked to excess weight haven't been on people's radar screens as having a weight component," said cancer prevention expert Graham Colditz, MD, DrPH, at Washington University School of Medicine in St. Louis, who chaired the IARC Working Group.

Eating a healthy diet, maintaining a healthy weight, regular physical activity, quitting smoking and alcohol can have a significant impact on lowering the risk of cancer. “Public health efforts to combat cancer should focus on these things that people have some control over," said Colditz.

The study suggests that maintaining a healthy weight over the decades could help reduce cancer risk. But, shedding those extra kilos is hard for many people. "Rather than getting discouraged and giving up, those struggling to take off weight could instead focus on avoiding more weight gain," said Colditz.

Few more cancers have been added to the list of cancers that occur due to excess weight gain. The researchers noted that “higher the body mass index (BMI), greater the cancer risk.”

The study showed that cancer risks associated with overweight and obesity were similar for men and women, consistent across geographic regions - North America, Europe, Asia and the Middle East. Excessive accumulation of fat leads to overproduction of hormones such as estrogen, testosterone, and insulin that promote inflammation and cancer growth.

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"Significant numbers of the U.S. and the world's population are overweight. This is another wake-up call. It's time to take our health and our diets seriously," Colditz said. The findings of the study are published in The New England Journal of Medicine.

Relationship Between Obesity and 8 Newly Listed Cancers

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Stomach Cancer

Globally, stomach cancer is the fifth most common type of cancer. It is more common in men than women. A review of 89 global studies found that overweight and obesity are the major risk factors for cancer of the upper stomach. Other risk factors are excessive consumption of alcohol and processed meat.

Liver Cancer

Accumulation of excess body fat is linked to increased risk for liver cancer. Body fat releases hormones in the bloodstream that contribute to insulin resistance and inflammation, promoting tumor growth. Liver cancer is the tenth type of cancer to be linked to overweight and obesity.

Gallbladder Cancer

The risk of gallbladder cancer  and obesity is due to higher frequency of gallstones (a main risk factor for gallbladder cancer). High scores of BMI increases the risk of gallbladder cancer by 25 percent. Globally, gallbladder cancer is the 20th most common cancer. A report by the American Institute of Cancer Research reaffirmed the findings of previous research by the World Cancer Research Fund International (WCRF International) that overweight and obesity increase liver cancer risk.

Pancreatic Cancer

Pancreatic cancer among overweight and obese individuals is due to increased waist circumference. A study published in the American Journal of Clinical Nutrition found that longer a person is obese (from age 18 to 50), the more risk increases for pancreatic cancer. For every ten years of being overweight or obese, the risk of pancreatic cancer increased by 6%. The study also showed that the risk increases among those who have diabetes.

Ovarian Cancer

Ovarian cancer is the eighth type of cancer linked to overweight and obesity. Ovarian cancer is the fifth leading cause of cancer death because women are diagnosed only at the later stages. Health experts advise that women should maintain a healthy weight to help protect against the deadly cancer.

Meningioma (Type of Brain Tumor)

A meta-analysis published in the journal Neurology linked overweight and obesity to an increased risk of a type of brain tumor called meningioma. It is rare cancer that occurs at a rate of five to eight cases per 100,000 people per year. The study found that overweight people were 21 percent more likely to develop meningioma compared to normal weight people. Fifty-four percent of obese people are likely to develop meningioma.

Thyroid Cancer

In the past three decades, obesity and overweight have contributed to the rise in thyroid cancer incidence. A study published in the journal Obesity Reviews found that the risk of thyroid cancer was stronger among individuals with a BMI score 30.0 kg/m2 and above. Another study published in The Journal of International Medical Research found that overweight increased the risk of thyroid cancer risk among non-Asians, but not among Asians.

Multiple Myeloma

Multiple myeloma is the second most common cancer of the blood. A new study found that approximately one-third of multiple myeloma patients are obese. Maintaining a healthy body weight could prevent the risk of developing multiple myeloma. Besides the evidence of obesity as a major risk factor for multiple myeloma, obesity plays a key role in the prognosis of the disease. The overall survival rate in obese patients with multiple myeloma was shorter compared to patients with normal weight, according to a study published in the journal Leukemia.

Tips to Reduce Cancer Risk

Diet

• Eat a balanced diet containing more fruits and vegetables, whole grains and legumes.
• Follow a Mediterranean diet  (plant-based foods and healthy fats such as olive and canola oil)
• Avoid refined sugars and animal fat
• Avoid high-calorie foods and drinks
• Limit consumption of processed meat

Lifestyle

• Avoid the use of tobacco products
• Limit or avoid alcohol consumption
• Maintain a healthy weight
• Engage in regular physical activities such as aerobics, walking and jogging
• Get regular health checkup

 References:

1. Skin cancer - Protect yourself from the sun - (http://www.mayoclinic.org/healthy-lifestyle/adult-health/in-depth/cancer-prevention/art-20044816?pg=2)
2. Obesity and Cancer Risk - (http://www.cancer.gov/about-cancer/causes-prevention/risk/obesity/obesity-fact-sheet)
3. New Liver Cancer Report, New Links Emerge: Coffee Is Protective, Obesity Increases Risk - (http://www.aicr.org/press/press-releases/2015/liver-cancer-report-new-links-emerge-coffee-protective-obesity-risk.html?referrer=https://www.google.co.in/)
4. Obesity throughout Life Increases Pancreatic Cancer Risk - (http://www.aicr.org/cancer-research-update/september_25_2013/cru-obesity-through-life-increases-pancreatic-cancer-risk.html?_ga=1.238750336.1809873846.1472103897)
5. Overweight, obesity and thyroid cancer risk: a meta-analysis of cohort studies. - (http://www.ncbi.nlm.nih.gov/pubmed/23321160)

Source-Medindia