Obesity, some cancers linked

By BRIAN SODOMA

VIEW ON HEALTH

It has become common knowledge that being overweight or obese increases a person’s risk for certain health problems. Cancer’s link to fat and obesity has seen its share of research queries during the past few decades. Today experts are still looking for what are clearly very elusive answers.

BULGING FACTS

It’s no secret that America is engaged in an uphill battle against its growing collective waistline. The Centers for Disease Control and Prevention uses the body mass index to gauge whether a person is overweight, obese or of a normal weight. Taking a person’s weight and dividing it by the square of his or her height calculates BMI. A figure between 25 and 29.9 indicates that a person is overweight. Above 30 means he or she is obese. A range of 18.5 to 24.9 is considered normal.

In 2009, the CDC reported that only the states of Colorado and the District of Columbia had a prevalence of obesity lower than 20 percent. Thirty-three states had a greater than 25 percent prevalence, nine of those topped 30 percent.

FAT AND CANCER

The National Cancer Institute constantly monitors the connections being found between obesity and certain diseases. In its 2009-10 Progress Report, it estimated that prevention of obesity “reduces the risk for many of the most common cancers, such as colon, postmenopausal breast, uterine, esophageal, and renal cell cancers.”

The report estimates that 20 to 30 percent of some of the most common cancers may be related to being overweight, a lack of physical activity or both. It went on to say that being overweight could account for up to 14 percent of cancer deaths in men and 20 percent of cancer deaths for women. The survey looked at adults ranging in age from 20 years old to 74 between 1971 and 2008.

Further, a 2007 NCI study looked at prostate cancer and obesity. Done in cooperation with the American Association of Retired Persons, the study involved nearly 287,000 males aged 50 to 71 between 1995 and 2001. The report found that in that time, 9,986 of the men developed prostate cancer, of which 173 died from the disease.

Men who were overweight, or with a BMI of 25 to 29.9, had a 25 percent increased risk of death from prostate cancer, while those considered mildly obese with a BMI between 30 and 34.9 saw a 46 percent increased risk of death. Even more, those considered severely obese (with a BMI of 35 or higher) doubled their risk of death, the study concluded.

“The growing prevalence of obesity in Western countries is alarming, and reducing the risk of prostate cancer death is only one among many health reasons to maintain a healthy weight through diet and exercise,” according to a statement in the report from Dr. Margaret Wright, a member of NCI’s Division of Cancer Epidemiology and Genetics.

BRINGING IT ALL TOGETHER

The American Institute for Cancer Research is engaged in on-going research linking fat and cancer. It published a 2007 report after putting together a panel of experts that reviewed more than 7,000 research papers on the subject.

The report indicated that excess fat as well as alcohol, red meat and processed meat consumption increases the risks of developing cancer.

Alice Bender M.S., R.D. and member of the American Institute for Cancer Research who has been monitoring the progress of the research since initially published, says the findings are “not static and are continuously being reviewed.”

She says the links between excess body fat and colorectal, post-menopausal breast, endometrial, esophageal, pancreas and kidney cancers are the strongest. Bender says certain “biological mechanisms” are being studied at universities around the world to bring more conclusive scientific evidence to the links.

One biological mechanism being studied, she says, is body fat’s potential to increase the level of steroids and other hormones in the body, many of which are linked to cancer growth. She gives the example of estrogen in women promoting cell growth and the spread of breast tumors. Most of that evidence has been found in animals, but it could be the case in humans too, she offers.

Excess body fat also increases chronic inflammation, which also causes cell proliferation and can influence how fast and far cancer can spread, Bender adds. Fat also increases oxidative stress, which can create free radicals in the body, promoting cell damage and the beginning of cancer cells, she says.

“What (fat) really does is create a whole environment in the body where it can cause cells to become cancerous and to spread. Where in the past the body may have been able to take care of that, but now the fat is there and (the body) can’t,” she says.

Bender says AICR estimates that if the population were at a healthy body weight, about 100,000 cancer cases per year could be prevented. If everyone were physically active, she adds, roughly a third of the most common cancers could be prevented.

“We want people to understand that the (dietary) choices they make have an impact,” she says.

LOCAL RESEARCH

One doesn’t need to set foot outside the Silver State to find expertise on the subject of linking fat and cancer. The state’s flagship cancer research institution, Nevada Cancer Institute (NVCI), is currently using some unique technology to view how lipids behave in the blood stream and one of its researchers has published findings on fat’s role in the spreading of cancer in mice.

In January 2009, Thuc T. Le, then at Purdue University in Indiana and now a researcher at NVCI, published his findings in several medical journals. Le and fellow researchers injected lung cancer cells into the hind legs of 32 mice. They then fed 12 of them with a high fat diet of 34.9 percent fat and 20 of the mice with low fat, or a 4.25 percent fat, diet. The results yielded a 300 percent increase in the number of metastasizing cells.

Le uses CARS (Coherent anti-Stokes Raman scattering) microscopy technology to study lipids in the blood. The technology was originally developed by Ford Motor Company to measure and analyze exhaust particles in cars, and Le’s research represents the first biomedical application for the laser technology. Le is now hoping that continued research using CARS will allow him to make the case for using lipid-lowering drugs in cancer prevention and treatment.

“CARS is very sensitive to lipids and what we found is that we can detect tumor cells without needing to draw blood,” Le adds.

CANCER’S SWEET TOOTH

But there are those who believe we may be putting the cart before the horse when it comes to fat’s connection to cancer. It is not so much obesity and fat as it may be how we’ve gained the weight, says Dr. Robert Su, an east-coast anesthesiologist and pain management physician since the 1970s, who retired in the late 1990’s. Since that time, he has dedicated much of his research to the link between sugars and carbohydrates and disease. To Su, sugar may be the link to cancer Americans and their fat-obsessed dieticians are overlooking.

“Fat is not the problem. Inflammation is the cause for cancer,” Su notes, which also falls in line with what Bender and the AICR are purporting. “What you’ll find is that every time the blood sugar goes up from sugar or carbohydrate intake, inflammation goes up.”

Su, who has studied more than 2,000 peer-reviewed articles, found that after he retired he began to have blood pressure problems. Medication and a sodium-limiting diet did not bring his blood pressure down. He lost weight, but still could not reduce his blood pressure. But once he limited his carbohydrate consumption, the blood pressure dropped along with the weight. Su re-asserts that the inflammation and weight gain caused by sugar is the overlooked cancer link.

“Excess glucose, with the help of insulin, will be turned into fat. If you feed people with carbohydrates more fat is going to be generated in the bloodstream. … Fat is not the problem. Carbohydrates are,” he adds.

SUGAR, FAT AND ENERGY

Le also agrees that a lot of the literature out there today will point in the direction of linking glucose and cancer cells. Scientific evidence dating back more than 80 years ago to Germany has brought about what is referred to as the “Warburg Effect.”

In the 1920’s Nobel laureate, Otto Warburg, published his observations on cancer cells and their ability to fuel themselves by glycolosis, which creates energy by fermenting sugar in a cell’s cytoplasm. Healthy cells, however, create energy by metabolizing sugar in the mitochondria. This difference between healthy and cancer cells, Warburg argued, was the primary cause for cancer.

Chronicled in a Time Magazine story in 2007, German researchers at University of Wurzberg are now testing an Atkins-type diet in the treatment of cancer patients with hopes of further understanding the potential sugar-cancer connection. The study is going the extra mile of even feeding patients a high-fat diet. Results and updates on the study haven’t been released since it commenced in 2007.

Le, however, says it all comes down to cancer cells needing energy to proliferate. Doubling the size of a cell membrane is required in order for any cell, be it cancerous or not, to reproduce, he explains.

Separating the type and amount of energy sugar or fat provide in order for a cell to reproduce should be taken into consideration. Le explains that lipids are important because cancer cells will break down glucose to build lipids. He makes the analogy of a person driving to a new neighborhood. Before he or she learns of where the nearest grocery store is, the person must bring food along to last until another food source is found. Lipids are that source for cancer cells, Le explains.

“Lipids serve as an excellent source of energy,” he says. “When you move to a new location, you always need to bring that nutrient with you. … Why lipid-rich cancer cells are aggressive is due to the energy needs of the cell while they are moving.”

DIET SUGGESTIONS

While the AICR suggests staying away from red meat and alcohol is key to maintaining an appropriate weight and reducing cancer risk, others say watching sugar consumption in order to keep weight down is also important. For more information on obesity and cancer research, visit www.cancer.gov. In addition, Dr. Su’s Web site, www.carbohydratescankill.com also provides information and resources on carbohydrate’s link to cancer, inflammation and other health problems.