Obesity and Cancer-Risk, Linked

“Overweight individuals are more likely to die from all causes, including heart disease and cancer,” explains Dr. Fuhrman. Wait, it gets worse. Here’s an excerpt from the new Food Scoring Guide:
The ever increasing waistline of America is not merely a cosmetic issue. This March toward national obesity is taking a dramatic toll on our health and economy, and is causing medical and financial tragedies for more and more families. At present, two thirds (67%) of American adults, and nearly one-third (31%) of our children, are overweight or obese. Over the past thirty years, the average weight of an American male has increased 27 pounds (from 164 pounds to 191 pounds). Childhood obesity has tripled over the past twenty years. Because of America’s eating habits, the U.S. Center for Disease Control (CDC) predicts that the current generation of children will be the first in our nation’s history to live shorter lives than their parents.
That’s a daunting a prospect. Now, not to scare the living daylights out of you, but you’d think all the health complications from being obese would keep people from letting themselves go. More from Dr. Fuhrman:
Health Complications of Obesity
  • Increased overall mortality
  • Adult onset diabetes
  • Hypertension
  • Degenerative arthritis
  • Coronary artery disease
  • Obstructive sleep apnea
  • Gallstones
  • Fatty infiltration of the liver
  • Restrictive lung disease
  • Cancer
Getting winded when I bent over to tie my shoes made me get my act together, but it could have been worse—much worse. A new study has determined that obesity does in fact increase cancer-risk. HealthDay News reports:
"This is a profoundly important issue. Obviously, the obesity epidemic is a huge problem itself, and the relationship to cancer is only one of the many adverse health effects of being overweight and obese," said Dr. Michael Thun, head of epidemiological research at the American Cancer Society. "The evidence has been accumulating now for over 10 years. . . This study tries to provide a quantitative measure of how much the relative risk goes up with each increment, basically jumping from one BMI [body-mass index] category to another."

Although extra fat has already been identified by research as a risk factor for several different types of cancer, Thun said, "the problem of obesity is so large and so difficult to solve that there's a very sound reason for ongoing studies of things that have become increasingly well-known, just because it helps the momentum in stimulating approaches that will actually help people maintain a healthy weight."
Whether its cancer-risk, heart disease, diabetes, or whatever, feeling better and looking better, has got to be inspiration enough—right? If not, get a load of this research in the BMJ. From The Million Women Study:
Increasing body mass index is associated with a significant increase in the risk of cancer for 10 out of 17 specific types examined. Among postmenopausal women in the UK, 5% of all cancers (about 6000 annually) are attributable to being overweight or obese. For endometrial cancer and adenocarcinoma of the oesophagus, body mass index represents a major modifiable risk factor; about half of all cases in postmenopausal women are attributable to overweight or obesity.
Honestly, things like cancer scare the crap out of me. So I after I read stuff like this, I grab some lettuce and hit the treadmill. Then afterwards, I grab some carrots and a Yoga mat. And after that, I usually collapse.
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Karen in DE - February 18, 2008 11:11 AM

OK, note the word "associated." This study did NOT prove that obesity CAUSES cancer, although the conclusions you cite seem to say that (but doesn't really.)

There is a vast difference between association and causation. And scientific reporting (or blogging) that does not distinguish between the two can lead to serious misunderstanding.

In fact, it appears more and more that obesity is generally a disease condition. That is, it is caused by various factors, especially but not limited to, endocrine function. And of course, what we eat and how we exercise, as well as our genetic makeup and apparently even what our mother ate during or even prior to pregnancy, contributes to those causal factors.

It's not much of a stretch to understand that these factors may also contribute to initiation and growth of cancer. Hence, obesity and cancer would be *associated,* but one would not necessarily cause the other. In fact, there is some research out there to support at least one mutual causal factor (elevated blood glucose.)

Why is this distinction important? Well, for the sake of scientific accuracy, for one. But it is also important in making sense of the fact that many people get cancer who are NOT obese. And vice versa.

So, an obese person may read a summary of that paper and conclude that JUST by losing weight he will automatically lower his risk of cancer. He thinks he read that his excess fat causes the cancer, and by getting rid of the excess fat, his risk will be lower. BUT... it's probably not just the fat. His REAL cancer risk is probably more strongly influenced by things in his life other that his % fat... such as what he eats and the nutrient content thereof, what his insulin and blood glucose levels are, how and how much he exercises, etc.

We here understand all that. But many folks do not. And there they go, starting the Atkins diet, losing weight/fat, and thinking they are lowering cancer risk. And articles like this don't provide them with info to suggest their strategy might not accomplish their goal of a lowered cancer risk.

Gerry Pugliese - February 18, 2008 1:23 PM

Hey Karen in DE-

Point well taken, I wasn't too worried about it because I've explored the diet-cancer link before.

But thanks for reminding me to hammer home the point more often. :)


OG - March 3, 2008 6:53 AM

Obesity and Cancer-Risk, Linked
The author of this blog is commenting on articles that he has found which have stated that obesity is a risk factor for cancer. He goes on to state that all the complications from being obese should be enough to make a person think twice before letting themselves go since getting winded while tying his shoes was enough of a health scare to make him shape up.

The link between cancer and obesity should come as no surprise to anyone since obesity has already been linked to a variety of diseases: like high blood pressure, coronary heart disease, stroke and diabetes. Postmenopausal breast, colon, endometrium, kidney and esophagus cancer have all been linked to obesity and physical inactivity. Being overweight and obese has been shown to be the cause of 14 % of cancer deaths in men and 20% of cancer deaths in women.(1)

Postmenopausal women who do not use hormones and are obese are at an increased risk to develop breast cancer. Approximately, 11,000-18,000 women over the age of 50 (in the US) could avoid developing breast cancer if they kept their body mass index (BMI) under 25. Postmenopausal, obese women tend to produce high levels of estrogen since estrogen is produced in fat tissue. This increased estrogen production leads to the development of estrogen-responsive breast tumors in obese women who do not use menopausal hormones to regulate their estrogen production. Obesity also hampers the detection of early stage breast cancer causing many women to be diagnosed at later stages when the disease has spread.(1)

A high body mass index due to physical inactivity and a high level of abdominal fat has also been associated with development of colon cancer in men. These factors lead to the development of insulin resistance and hyperinsulinemia. Insulin resistance is a condition in which the body is producing high levels of insulin since the cells of the body have become resistant to normal levels of insulin.(2) Hyperinsulinemia is a condition in which there is too much insulin circulating in your blood.(3) These conditions can increase the level of free and bioactive insulin growth factor-I (IGF-I) found in your body and lead to the development of colon cancer since this factor stimulates tumor growth.(4)

Cancer of the endometrium was the first cancer to be associated with obesity.(5) The high levels of estrogen and insulin seen in obese women are thought to be contributing factors in the development of this disease. Currently, obese women have been shown to have at least a two fold greater risk of developing endometrial cancer than lean women.(1)

Although the mechanisms that link obesity to kidney cancer (renal cell carcinoma) are not well understood, obese individuals have a two fold greater risk of developing this type of cancer over men and women of normal weight. Scientists have theorized that the increase in estrogen and androgen seen in obese individuals leads to the development of kidney cancer.(1)

Esophageal cancer is becoming increasingly prevalent in obese individuals. Overweight individuals are at a greater risk of developing gastro-esophageal reflux disease (GERD), which oftentimes can lead to the development of malignant lesions. Although GERD has been shown to be one of the factors that increases your risk of developing esophageal cancer; it is not considered to be the mechanism that causes this type of cancer. Studies have shown that obese individuals who do not have GERD often develop esophageal cancer.(1,5)

Although the mechanisms that lead to the development of these cancers have not been entirely flushed out, one thing is certain: obese individuals are at a higher risk of developing cancer than individuals of normal weight. Obesity is currently an epidemic that is sweeping the globe. The highest prevalence is seen in the United States and the United Kingdom.(5) This should come of no surprise to anyone since we currently live in a society that basically lives off of fast food and thinks of gastric bypasses as a cure for weight loss. Who cares if you get fat? Eat a hamburger today and have it sucked out tomorrow.

The obesity epidemic that the world is facing is a direct result of the fast food society that has been carefully cultivated by the makers of foods like: Whoppers, Big Mac’s, Chalupas, and Fried Chicken. As children, we are unknowingly drawn to these foods since fast food restaurants promote them with playful characters like the Ronald McDonald clown, the cute Chihuahau, a king and a gentile old man cooking chicken. The inclusion of toys with certain meals made them even more popular. The truth is that the food found in a Happy Meal is just as dangerous and as addictive as the cigarettes that the Joe Camel character was pushing on kids in the late 1980’s. These foods have made their way into schools where a daily lunch may consist of a soda, fries and a hamburger. The addition of vending machines to school campuses has really hampered the fight against obesity.

The largest increases in childhood obesity occurred between the years of 1976-1980 and 1999-2002.(6) The increases seen between the years of 1976-1980 may be due to the changes that occurred in the federal tax code in 1976.(7) These changes allowed working parents to take a tax credit for child care expenses.(7) This tax credit most likely led to an increase in working mothers. The home cooked meals that were made by mom were quickly replaced with TV dinners and fast food during these years. Working mothers didn’t have as much time in their day to slave over a hot stove cooking a meal and relied on quick alternatives for dinner.

The increases seen in 1999-2002 may be due to the loss of physical education curriculum that occurred in schools during those years. The No Child Left Behind Act proposed by President Bush in 2001 has pressured schools to focus more on test scores and coursework.(8) Teachers are so focused on test scores that they have forgotten about the benefit of incorporating PE into a students’core curriculum and the students have suffered. In 1991, forty-two percent of students attended a daily physical education class.(8) By 2003, it was reported that only 28 percent of students attended a daily physical education class.(8) Physical education class is something that was tossed out of the education system with art and music. I remember a time when every student had an hour of PE and 30-45 minutes of recess. This gave students time to play games, learn about sports and nutrition, and move their bodies. Nowadays, you barely have enough time to finish your lunch before you’re shuffled off to another class. The focus on test scores and academics has created a generation that is physically inactive and more likely to be at risk for diseases associated with obesity like cancer.

Increases in childhood and adult obesity rates are also due to the expensive price of food. Low income families sometimes cannot afford to purchase fresh fruits and vegetables. Fast food is the affordable alternative. We currently live in a society where the dollar menu found at many fast food establishments can feed a family of four or two hungry graduate students for less than five dollars.

Unfortunately, a change in the obesity rates is not going to happen anytime soon. As we slowly become a more technology based society, physical inactivity will become more prevalent. Soon everyone will be getting in their car and driving the three yards it takes to get the mail. Walking will become a lost art as segways become afforadable to all.

The fight against obesity and cancer must start at home. Parents must start educating their children on the importance of nutrition and exercise. Losing weight and being fit must become a priority since it may save your life. Fresh fruits and vegetables must be made more affordable and the price of fast food must increase. If Congress passed legislation that forced fast food establishments to sell their food at exorbant prices; whole grains, lean meats, fresh fruits and vegetables might have a chance at a comeback. These changes would result in a decrease in cancer rates and people would live longer and healthier lives.

1. “Obesity and Cancer: Questions and Answers.” National Cancer Institute Fact Sheet. 16 March 2004. .
2. Mathur, Ruchi. “Insulin Resistance.” MedicineNet.com 26 April 2005. .
3. “Hyperinsulinemia: Is it diabetes?” MayoClinic.com. 07 December 2007. .
4. Giovannucci E. and D. Michaud. The role of Obesity and Related Metabolic Disturbances in Cancer of the Colon, Prostate, and Pancreas. Gastroenterology 2007; 132(6): 2208-2225.
5. Calle EE and R. Kaaks. Overweight, Obesity and Cancer: Epidemiological Evidence and Proposed Mechanisms. Nat Rev Cancer 2004; 4(8): 579-591.
6. Dietz WH and TN Robinson. Overweight Children and Adolescents. N Engl J Med 2005; 352: 2100-9.
7. Hollenbeck S and M. K. Kahr. “ Ninety Years of Individual Income Tax and Statistics, 1916-2005.” Irs.gov. Winter of 2008. .
8. Trickey, Helyn. “No child left out of the dodgeball game?” CNN.com 24 August 2006 .

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