Oesophagus Cancer Linked To Obesity In Australia

A rapid rise in cases of a deadly oesophagus cancer has been linked to Australia's obesity crisis, with doctors investigating whether fat tissue is feeding the tumours.

The incidence of adenocarcinoma of the oesophagus — one of the most lethal cancers — has increased fivefold in the past 25 years in Australia, according to David Whiteman, senior research fellow at the Queensland Institute of Medical Research.

"It's a real increase in cancer which you just don't see in epidemiological lifetimes," he said. "It's unprecedented to see a cancer come up so quickly."

Those at greatest risk appear to be obese people, especially men, who suffer from reflux and have smoked at some time.

Dr Whiteman has recently completed a study aiming to identify factors that might affect a person's risk of oesophageal cancer, with a particular focus on whether fat may be feeding certain cancers.

"There really is no question that this is an obesity-related cancer but the question is how and why?" he said.

"Could it be that the fat tissue itself is acting like a fertiliser? Is it producing an environment where if you have an early change that could turn into a cancer in someone with more body fat, that it is more likely to flourish, take root and grow than it would in a lean person who doesn't have the same amount of proteins flitting around the body?"

Dr Whiteman's study has been accepted for publication in the medical journal Gut, published by the British Medical Journal publishing group. His research team compared more than 1000 Australians diagnosed with oesophagus cancers with healthy people.


The participants were asked a number of questions including the nature of their symptoms prior to diagnosis.

"People often don't realise they have any problem until they get their food stuck when they swallow and when that happens usually the cancer is of a large size, which means it's resistant to treatment," Dr Whiteman said.

"It has a survival rate that's as bad as any of the bad cancers like pancreatic cancer."

According to Cancer Council Victoria, there were an average of 133 new cases of the cancer per year in Victorian men and women in 2002-04. Men are five to eight times more likely to get it than women.

One of the big risk factors associated with the cancer is reflux (heartburn) from the stomach, a condition more often suffered by overweight people.

Smoking is also a risk factor, even for people who have only smoked for a short time.

The director of Cancer Council Victoria, Professor David Hill, said the rise in adenocarcinoma of the oesophagus was concerning.

The Cancer Council has conducted a 20-year study of more than 40,000 Victorians, which looked at how lifestyle factors, including diet and exercise, affected a person's risk of developing certain cancers.

It was estimated that obesity contributed to 500 cancer deaths in Victoria each year.

The study, developed by Professor Graham Giles, found men and women who were considered overweight — with a body mass index over 25 — had an increased risk of adenocarcinoma of the oesophagus. Of the patients with the cancer, 45 per cent had the disease because they were overweight.

Professor Hill said certain cancers were associated with being overweight including cancer of the colon, endometrium, postmenopausal breast, kidney and myeloid leukaemia.

"This study shows how much impact you could make in reducing the burden of cancer by in fact changing the prevalence of the risk factor, in this case, overweight/obesity," Professor Hill said.

Sphere: Related Content

Gastric Bypass Surgery Increase Longevity And Drops Obese Weight

Gastric bypass surgery not only helps obese people drop weight and look better, it also helps them live significantly longer, according to two reports published on Wednesday.

The studies in the New England Journal of Medicine confirm what doctors had long suspected but never proved.

The years gained are significant, with life span prolonged by up to 40 per cent and rates of diabetes, cancer and heart disease all lower.

"The question as to whether intentional weight loss improves life span has been answered, and the answer appears to be a resounding yes," Dr George Bray of Louisiana State University wrote in a commentary.

More than 30 per cent of the US population is now considered obese, with severely obese people tending to die five to 20 years earlier than people of healthy weight.

At the same time, more than 100,000 stomach operations of some type are performed in the United States each year to help people lose weight.

One of the studies found that gastric bypass surgery - in which doctors reduce the size of the stomach to limit the amount of food a person can eat - cut the death rate by 40 per cent among 7,925 volunteers who had been followed for an average of seven years.

The risk of heart disease dropped 56 per cent, the diabetes rate was 92 per cent lower and the likelihood of cancer was 60 per cent less compared with 7,925 severely obese people identified by data from their drivers' licences.

But the news was not completely good for the surgery patients.

The chance of death from something other than disease, including accidents, suicide and poisoning, was 58 per cent higher in the surgery group.

Earlier research has shown that obese people who have the operation are more likely to suffer from mood disorders, post-traumatic stress disorder or the after-effects of childhood sexual abuse.

"After a mean follow-up of 7.1 years, in the surgery group, 171 deaths from disease were prevented per 10,000 operations," Ted Adams of the University of Utah School of Medicine and colleagues wrote in their study.

"On the other hand, there was an increase of 35 non-disease deaths per 10,000 operations, for a net prevention of 136 deaths."

The other study, conducted in Sweden, found that about 11 years after surgery, the death rate was 27 per cent lower among 2,010 patients who had undergone some type of operation, including gastric bypass, to lose weight.

That team, led by Lars Sjostrom of Gothenburg University, found gastric bypass produced the greatest sustained weight loss - about 25 per cent - and that the death rate during the follow-up period was 5 per cent in the surgery group, compared to 6.3 per cent among those who did not have an operation.

Sphere: Related Content

Obesity From Liver Defect

Scientists at the Monell Chemical Senses Center have identified a genetically-transmitted metabolic defect that can lead to obesity in some individuals. The defect involves decreased production of liver enzymes needed to burn fat and may help to explain why some people become obese while others remain thin.

The global obesity epidemic is believed to be caused in part by the increased availability and intake of high calorie foods rich in fat and carbohydrates. These foods promote weight gain in humans and other animals, leading to a diet-induced obesity. The propensity to gain weight and become obese when consuming a high-fat diet is at least partially controlled by genes.

Results of this study help explain the interaction between genes and diet that underlies diet-induced obesity, comments senior author Mark Friedman. They also point to a way to identify individuals at risk for dietary obesity, perhaps even during childhood before the development of unhealthy eating habits.

The current study, reported in the recent issue of Metabolism, demonstrates that genetic susceptibility to diet-induced obesity is due to a reduced capacity to burn fat.

Fat is one of the fuels that the bodys cells burn to provide energy. This process, known as fat oxidation, takes place inside mitochondria, the cells power plants for generating energy.

If the ability to oxidize fat is impaired, the bodys capacity to make energy is reduced. This leads to increased hunger and overeating, as the body tries to increase the amount of energy available to meet its needs.

When the diet is low in fat, a reduced ability to burn fat has relatively little impact on energy production. However, if fat oxidation is impaired and the diet is high in fat, a greater proportion of calories cannot be used and food intake increases to cover the energy deficit. Because fat fuels are stored in fat tissue when theyre not oxidized, the increased food intake causes weight gain.

To determine whether preexisting differences in fat oxidation might contribute to individual susceptibility to diet-induced obesity, Friedman and lead author Hong Ji used rats that differ in their genetic predisposition to gain weight and become obese when fed a high-fat diet.

The closely-related strains weigh the same and eat the same amount of calories when fed a low-fat diet. However, when switched to a high-fat diet, the strain that is obesity-prone overeats and becomes obese, while the obesity-resistant strain does not.

The scientists observed that even when eating a low-fat diet and still lean, the obesity-prone rats were less able to burn fat than were the obesity-resistant rats. This intrinsic deficit in fat oxidation was linked to a decrease in the capacity to make two liver enzymes. One, CD36, is responsible for transferring fat fuels into liver cells, while the second enzyme, acyl-coenzyme A dehydrogenase, begins the oxidation process in mitochondria.

When fed a high-fat diet, the obesity-prone rats overate and became obese, gaining 36% more weight than resistant animals. Fat oxidation was further compromised due to a decreased ability to make CPT1A, the liver enzyme responsible for transporting fat into mitochondria.

The inherited propensity to gain weight when eating a high-fat diet appears to be due to a preexisting limit on the ability to burn fat in the liver. This defect persists during the development of obesity and is then further compounded by additional deficits in the fat oxidizing machinery, comments Friedman.

Other studies in Friedmans laboratory have demonstrated that a decrease in fat oxidation and energy production in the liver generates a signal that stimulates eating. Experiments in his and other laboratories have also observed that therapys that increase fat oxidation reduce food intake and cause weight loss in obese rodents.

With this in mind, Friedman notes, The present findings point to fat oxidation in the liver as a target for the development of drugs that suppress appetite and promote weight loss in obese individuals.

Future studies will guide development of such interventions by examining more closely the function and activity of the target enzymes.

Sphere: Related Content

Bariatric Surgeries - A Ray Of Hope For The Morbidly Obese

Carolyn Sayre

Losing weight is an uphill battle — especially for the morbidly obese. Diet and exercise often fail. Drugs are not very effective. And in the end, many people suffer for years only to be left with one last and very expensive resort: surgery. That was certainly the case with Shawn Tarman, a 42-year-old woman from Willow Grove, Penn., who says she'd tried absolutely everything to lose weight. She finally resorted to gastric bypass surgery, a procedure that shrinks the stomach, and lost over 100 pounds.
In the last decade, bariatric surgeries like gastric bypass have become an acceptable method for treating the 15 million people in the U.S. who suffer from morbid obesity. "Obesity can be life threatening," says Dr. Philip Schauer, president of the American Society for Bariatric Surgery (ASBS). "And surgery is the next best step." Despite this, only 1% of patients who are eligible for surgery (those with a BMI over 40 or a BMI of 35 or more in conjunction with an obesity-related disease) actually get it. Sometimes, people just don't want to undergo a surgical procedure, but more often than not, obese patients are dissuaded by difficult insurance companies and are sometimes discouraged by doctors who feel they may not be the right age for the procedure.
But two new studies presented the annual meeting of the ASBS in San Diego, Calif., from June 11 to 16 show that adolescents and seniors, two age groups that have traditionally been urged to shy away from bariatric procedures, can actually benefit from surgical intervention. Another study shows that insurance companies could wind up spending less by approving bariatric surgery when compared to the life-long cost of obesity. And the latest piece of science shows that even though patients lose weight, they still need to be careful around certain indulgences — substances like alcohol have been found to have an even greater effect after surgery.
Researchers from the University of Texas Southwestern Medical Center in Dallas have found that teenagers handle bariatric surgery even better than adults. The study of 309 adolescents and 55,192 adults found that only 5.5% of teenagers had complications after surgery compared with 9.8% in adults. "There has always been a lot of concern that doing surgery in a young person, however extreme the case is, will carry a lot of complications," says Dr. Esteban Varela, lead author of the study and director of Minimally Invasive Surgery at VA North Texas Health Care System. "But it is even safer." Between 2000 and 2003, the number of teenagers who had bariatric surgery tripled. While the number is growing, with 771 adolescents signing up in 2003, teenagers still represent less than 1% of all bariatric surgeries — a number that will begin to increase as more doctors view the practice as safe.
From the same center, a similar study of the elderly population showed that seniors do not experience significantly more complications than young adults. In fact, only 13% of patients, age 65 and older, who had laparoscopic adjustable gastric banding (LAGB) — a surgical procedure that inserts a hollow band around the stomach to limit food intake — had complications. Even more compelling, nearly two-thirds of patients lost their excess weight and significantly improved their obesity-related conditions like diabetes. "No one questions whether we should offer knee or hip replacements to people over age 65," says David A. Provost, an associate professor at the University of Texas Southwestern Medical Center, who authored the study. "Weight loss surgery can provide similar quality of life improvements with less risk."
Even though Medicare and Medicare began covering bariatric surgery last year, many private insurance companies still do not want to pay for such an expensive procedure, which can cost anywhere from $10,000 to $40,000. However, a small preliminary study presented at the conference could change some of this thinking. Researchers found that the average cost of bariatric surgery is often completely recouped by the patient after three years, after which time the medical expenses of patients who did not have surgery are twice as high. "Patients who come in for surgery have a lot of medical problems," says Dr. Anita Courcoulas, lead author of the study. "It makes sense that it would end up costing less." A larger study still needs to be done, but this new research shows that surgery may actually be the cheaper option in the long term.
Most insurance companies will make patients jump through hoops before they will actually pick up the tab for bariatric surgery. Providers often require that patients lose a specified amount of weight by staying on a medically enforced diet plan. However, a new study from Duke University Medical Center found that 62% of bariatric surgery patients trimmed the excess fat regardless of whether they lost or gained 10 pounds before surgery. "There is no value in policies like this," says Dr. Eric DeMaria, the study's lead author. "If there is no value, we shouldn't use it as a requirement."
Bariatric surgery isn't a cure-all. There are still significant diet and lifestyle changes that need to be enforced. For example, a new study from Stanford University shows that patients who have gastric bypass are more susceptible to the effects of alcohol. Inspired by an episode of Oprah Winfrey in which most individuals who had undergone gastric bypass said they got drunk faster on less alcohol, the researchers decided to test this theory. The study found that for people who had the surgery, drinking 5 ounces of wine would give them an average blood alcohol level of 0.08, while the level of non-patients was only at 0.05. People who had the surgery also took 108 minutes to sober up, while non-patients only needed 72 minutes. Since the stomach is smaller after bypass, alcohol is absorbed faster and takes longer to clear the system.
It may be an uphill battle, but the evidence at this year's conference shows that gastric bypass surgery is more effective and safer that originally thought, and can significantly improve the quality of life for all ages. It certainly did for Shawn Tarman. "Eating used to be my life," Tarman says. "And surgery helped me get that life back."

Sphere: Related Content