Packing on the pounds gets a well-deserved bad rap. Most Americans understand that excess weight contributes to heart disease and diabetes, not to mention the urge to hide behind the kids in family photos. But obesity as a risk factor for cancer?

That seems to be the case. An increasing number of studies are finding that overweight and obese people are more likely to develop cancer of various kinds. At least half a dozen types of cancer are believed to be directly affected by weight.

“As time goes on, we’re realizing that obesity is related to more cancers than we originally suspected,” said Dr. Donald Hensrud, an associate professor of preventive medicine and nutrition at the Mayo Clinic College of Medicine.

Researchers are unable to prove that obesity actually causes cancer because requiring people to either gain weight or keep their weight down in clinical trials would be impossible. Most of the data come from observational studies, in which people who are thinner are probably doing many things differently than their heavier counterparts. Any number of those factors might be responsible for the difference in cancer rates.

Still, the evidence is “convincing” for a cause-and-effect relationship between obesity and postmenopausal breast, colon, endometrial, esophageal, kidney and pancreas cancer, according to a 2007 report from the World Cancer Research Fund and the American Institute for Cancer Research. The report also cited obesity as a “probable” cause of gallbladder cancer.

Scientists aren’t sure how obesity might affect cancer risk, but “there are some plausible biological mechanisms by which this may occur,” said Dr. Patricia Ganz, director of cancer prevention and control research at UCLA’s Jonsson Comprehensive Cancer Center.

One popular explanation is that extra weight boosts the body’s production of hormones such as estrogen, insulin and insulin-like growth factor 1 — all of which have the potential to promote the growth of certain tumors. Another possibility is that fatness contributes to cancer growth by causing cells to divide more rapidly.

Mechanical factors may play a role in certain types of cancer. In the case of esophageal cancer, the culprit seems to be acid reflux. People who are overweight are more likely to experience chronic reflux, which can lead to precancerous changes by eroding the lining of the esophagus.

The suspected higher risk of gallbladder cancer might be explained by the increased tendency of obese people to develop gallstones. These stones cause inflammation that could promote cancer.

Putting a number on it

Rates of obesity have steadily increased over the past few decades, more than doubling from 15% of adults in the early 1970s to 34% of adults in 2005-06, according to data from the National Health and Nutrition Examination Survey. Cancer rates also increased somewhat during this period, from a rate of 4 in 1,000 in 1975 to 4.56 per 1,000 in 2006 —although rates peaked in 1992 and have since been on the decline.

Scientists don’t know how much of this increase in cancer is real. Much of it appears to reflect the fact that we now regularly go looking for cancer with mammograms and prostate specific antigen tests, which is one more reason why the relationship between obesity and cancer is so difficult to study.

The World Cancer Research Fund and the American Institute for Cancer Research made an attempt to quantify the relationship in a 2009 policy report. The report concluded that excess body weight has the largest effect on endometrial cancer, causing an estimated 49% of cases. This translates into an extra 20,700 people with endometrial cancer per year.

The policy report also calculated that being overweight or obese causes 35% of esophageal cancers (5,800 people per year), 28% of pancreatic cancers (11,900 people per year), 24% of kidney cancers (13,900 people per year), 21% of gallbladder cancers (2,000 people per year), 17% of breast cancers (33,000 people per year) and 9% of colon cancers (13,200 people per year) .

Dr. Moshe Shike, an attending physician at Memorial Sloan-Kettering Cancer Center whose research focuses on cancer prevention, said he was skeptical about the idea of putting a number on something so slippery, saying that this implies accuracy where none exists. “We don’t know the magnitude of the effect,” he said.

Dr. Michael Thun, head of epidemiologic research for the American Cancer Society, agreed that the percentages are imprecise, but pointed out that numbers are often the best way to get results. “Numbers carry a strong message, just as estimates of death caused by smoking were very important to tobacco control,” he said.

Most of the studies on weight and cancer risk define obesity using body mass index (BMI), a number that accounts for weight in relation to height. Someone who stands 5-foot-7 is considered “overweight” at 159 pounds and “obese” at 191 pounds. A third of Americans are overweight, and another third are obese.

But the real culprit is fat, not weight, so a football player-type with lots of muscle and little flab would not be at increased risk even if his BMI fell into the “overweight” category.

The effects of weight loss

If excess weight increases the risk of cancer, can losing weight reduce the risk? Preliminary research suggests that it might. At least two large, published studies have found that people who undergo gastric bypass surgery are significantly less likely to develop cancer or die from it than severely obese people who don’t undergo the weight-loss procedure.

READ MORE  Overweight, obese people more likely to get certain kinds of cancer – latimes.com.

Ninety-seven per cent of people dont list being overweight as a cancer risk, according to a Cancer Research UK survey out today Tuesday.

After smoking, being overweight or obese is one of the biggest cancer risks.

But in a survey of nearly 4,000 people, only three per cent mentioned keeping a healthy bodyweight as something people could do to reduce their risk of cancer.

And seven per cent of those surveyed failed to name a single positive change people could make to help to prevent the disease.

Sara Hiom, director of health information at Cancer Research UK, said: “Encouraging people to change their behaviour is often difficult, but the first step is to build awareness that these changes are worth making.

“We have estimated that more than 13,000 cases of cancer could be prevented each year if everyone maintained a healthy weight.

“While many people may associate weight with being healthy in general, this survey shows that most people don’t link it directly with their risk of cancer, or don’t know how much it can reduce their risk.”

Two thirds of people surveyed mentioned giving up smoking as a way to reduce cancer risk.

Fifty-nine per cent of people said that food and diet was important, and 29 per cent understood that exercising more would help.

Twenty-two per cent of people, unprompted, said alcohol influences our risk of the disease, and 11 per cent said they knew that protecting your skin in the sun was important.

Sara Hiom added: “It may be hard for people to make the link between obesity and an increased risk of cancer because we generally associate having the disease with being underweight. But carrying extra weight means producing more chemicals in our bodies that can cause cancer to develop.

via Cancer Research UK : 97 per cent unaware of the link between weight and cancer .

Among cancers which affect both sexes, men are 60% more likely to develop the disease and 70% more likely to die from it, Cancer Research UK said.

There is no known biological reason for this but it may be because women take better care of themselves, they said.

Experts said men needed to be made aware of the risks they faced.

It is thought half of all cancers can be prevented through lifestyle changes.

For the latest report, published to coincide with Men’s Health Week, researchers first analysed data on all cancers from 2006 and 2007.They found that overall men are 40% more likely than women to die from cancer and 16% more likely to develop the disease in the first place.

But excluding breast cancer and other cancers that are gender specific, as well as lung cancer which is more likely to affect men because more men smoke, the difference between the sexes was far greater.

TOP MALE CANCER KILLERS 2007 Lung: 24% of all cancer deaths Prostate: 13% Colorectal: 10% Oesophagus: 6% Pancreas: 5%

The researchers had expected to see that men and women are just as likely as each other to develop and die from the disease.

However, the figures showed that men are significantly more likely than women to be diagnosed with and die from every one of the specific types of cancer considered, apart from melanoma.

‘Surprise result’

Professor David Forman, information lead for the National Cancer Intelligence Network, which helped carry out the research, said: “For many of the types of cancer we looked at that affect both sexes, there’s no known biological reason why men should be at a greater risk than women, so we were surprised to see such consistent differences.”He added: “Men have a reputation for having a ‘stiff upper lip’ and not being as health conscious as women.

“What we see from this report could be a reflection of this attitude, meaning men are less likely to make lifestyle changes that could reduce their risk of the disease and less likely to go to their doctor with cancer symptoms.”

Professor Alan White, chairman of the Men’s Health Forum, said men were generally less aware that factors such as smoking, carrying excess weight around the waist, having a high alcohol intake, a poor diet and family history all contributed to an increased cancer risk.

However, he said more research was needed on the causes of the gender gap and services needed to do more to reach out to men.

Professor White told the BBC: “Men have got a certain degree of responsibility to look to their lifestyle, but the services also have to be reaching out to men.

“If you think that nearly 14m men work full-time and of those 28% are working over 45 hours, then getting to the services is actually very problematic.

“And it’s not just the GP, it’s smoking cessation services, it’s weight loss services.

‘Get it checked’”We have to look very much more at how we change the services so they are more male appropriate.

“I think if you are suffering from something and it’s not going away, then get it checked out. That’s the simple message.”

The government’s cancer tsar, Professor Mike Richards, said there was no doubt of the gravity of the findings.

Prof Richards told the BBC: “I agree with Professor White that the scale of this has come as a surprise even to researchers.

“There seems to be no doubt – there is a higher risk of getting cancer and a higher risk of death.

“That maybe due to different ways of approaching the health services and being less likely to seek help.

“We certainly need to make men of these risks, of the lifestyle factors.”

Sara Hiom, director of health information at Cancer Research UK, said: “We know that around half of all cancers could be prevented by changes to lifestyle and it’s worrying that this message could be falling on deaf ears for men.

“Delays in reporting symptoms to a doctor could be helping to fuel this gender gap in cancer mortality.”

BBC NEWS | Health | Men warned of greater cancer risk.

The YouGov survey of 2,400 people for the World Cancer Research Fund (WCRF) found more than half thought scientists were always changing their minds. More than a quarter said health advice changed constantly and the best approach was to ignore it completely. But the WCRF said its advice, including eating more fruit and vegetables, had stayed the same for more than a decade.

The WCRF says that most scientists agree about the steps people can take to reduce their risk of cancer – and that this advice has largely stayed the same for the last 10 years. It is thought that about a third of the most common cancers could be prevented through eating a healthy, balanced diet, being physically active and maintaining a healthy weight.

In terms of diet, scientists agree that eating plenty of fruit and vegetables and limiting intake of red and processed meat, salt and alcohol can reduce cancer risk.

Richard Evans, head of communications for WCRF, said: “It is a cause for concern if people are not listening to cancer prevention advice because they have the impression that scientists are always changing their minds.

“The fact is that WCRF and other cancer charities agree on the best ways of reducing cancer risk and this advice has stayed broadly the same for quite a long time.

“A decade ago, we were recommending that people eat a plant-based diet, be physically active and maintain a healthy weight and this is still the case today.”

Mr Evans admitted there had been some changes to advice in recent years – but these were not abrupt about turns.

For instance, the evidence linking body fat with cancer has become much stronger over the last 10 years.

This has led to scientists to giving a greater emphasis to the importance of maintaining of a healthy weight, making it the second most important thing one can do to ward off cancer, after refraining from smoking.

Single studies

However, Mr Evans said: “The idea that the advice from scientists changes with the wind is just not right.

“The problem is that when people hear about a single study suggesting a particular food might be good for us, it is easy to assume scientists are now telling us to start eating it.

“With the large number of new studies being published, it is perhaps not surprising that people get the impression cancer prevention advice is always changing.

But these single studies are usually only a single piece in a jigsaw and on their own are not strong enough evidence to make conclusions.

“Often, they will be useful in giving us a lead that is worth following up with more research but should not be used to form the basis of advice.”

The survey also suggested older people were most cynical about cancer prevention advice.

Jessica Harris, of the charity Cancer Research UK, said: “It’s worrying if so many people think that scientists are constantly changing their minds about how to prevent cancer.

“Experts across the world agree that the best ways to reduce your risk of cancer are not smoking, keeping a healthy weight, drinking less alcohol, eating a healthy, balanced diet, being physically active and staying safe in the sun.

“These messages have not changed in recent years and are backed up by convincing evidence built up through decades of research.”

BBC NEWS | Health | Britons wary over cancer advice.

Kristin Anderson, Ph.D., associate professor and cancer epidemiologist with the University of Minnesota’s School of Public Health and Masonic Cancer Center, led the research team on this study. She presented the findings Tuesday at the 2009 annual meeting of the American Association of Cancer Research in Denver.

“I’ve focused my research on pancreatic cancer for some time to identify ways to prevent this cancer because treatments are very limited and the cancer is often rapidly fatal,” Anderson said. “Our findings in this study are further evidence that turning down the heat when grilling, frying, and barbecuing to avoid excess burning or charring of the meat may be a sensible way for some people to lower their risk for getting pancreatic cancer.”

In previous research, Anderson found an association between pancreatic cancer and cancer-causing compounds (heterocyclic amines and benzo(a)pyrene) that form on the surface of red meat, such as steak, during high-heat cooking; the levels of the carcinogens depend on the cooking temperature and the degree of doneness. In that research, both sick and healthy participants reported on their past diet.

This new study was a prospective analysis in which disease-free participants reported on their typical diet, and then they were followed to track their health status. Anderson and her colleagues used information participants enrolled in the National Cancer Institute – sponsored PLCO (prostate, lung, colorectal, and ovarian) Screening Trial provided about their meat consumption, preferred cooking methods and doneness preferences.

Over a nine-year period, Anderson and her colleagues identified 208 cases of pancreatic cancer.

“We found that those who preferred very well-done steak were almost 60 percent more likely to get pancreatic cancer as those who ate steak less well-done or did not eat steak,” Anderson said. “Furthermore, when we looked at amount of consumption with doneness preferences, we found that those with the highest intake of very well-done meat had a 70 percent higher risk for pancreatic cancer over those with lowest consumption.”

In addition to turning down the heat, Anderson offers these suggestions:

- Cut away parts of red meat that are burned or charred

- Before grilling, microwave meat for a few minutes and pour off the juices, which contain many of the precursors of the cancer-causing compounds

- When grilling, do not let flames lap at the meat; wrap meat in foil to protect it from the direct flame

- Cook meat in water or another liquid to prevent meat from getting too hot.

HometownSource.com – U of M study shows eating burned meat increases risk of pancreatic cancer.

Almost 19,000 people a year in the UK are diagnosed with cancer that could have been prevented if they were a healthy weight, an expert says.

Professor Martin Wiseman said if everyone had a body mass index (BMI) under 25 it would make a big dent in the incidence of cancer.

Cancers of the breast, bowel, kidney, pancreas, oesophagus and womb lining are among those linked to obesity.

Professor Wiseman is an adviser for the World Cancer Research Fund (WCRF).

The WCRF recommends that people try to be as lean as possible without becoming underweight.

A healthy BMI is defined as between 18.5 and 25, but, for example, scientists estimate that someone at the top of the healthy weight range is 15% more likely to develop bowel cancer than someone at the bottom of it.

This is the reason we recommend people aim to be as lean as possible without becoming underweight.”

However, Professor Wiseman said a recent survey had showed that almost 40% still did not know that excess body fat was a cause of cancer.

“This means we need to do more work to spread the message that maintaining a healthy weight is something positive people can to reduce their risk of developing cancer later in life.”

Dr Ian Campbell, medical director of the charity Weight Concern, said: “The message has to be that being overweight increases the risk of some forms of cancer but losing weight, even as little as 5kg can significantly reduce the risk.

“Getting BMI down to below 25 is ideal but not achievable by everyone. But every pound lost counts towards decreasing risk and is worth the effort.”

Tam Fry, of the National Obesity Forum, agreed that keeping BMI down to 25 would have a big impact on cancer.

Mr Fry said the only way to tackle the problem was to monitor children much more closely than was currently done, and to take action if they showed signs of a weight problem.

He said: “We have got to prevent people becoming overweight in the first place, once the milk has been spilt it is impossible to clean up the mess.”

The WCRF also recommends that people limit their consumption of energy dense foods, and avoid sugary drinks.

via BBC NEWS | Health | Weight ‘fuels preventable cancer’.

There was a time when red meat was a luxury for ordinary Americans, or was at least something special: cooking a roast for Sunday dinner, ordering a steak at a restaurant. Not anymore. Meat consumption has more than doubled in the United States in the last 50 years.

Now a new study of more than 500,000 Americans has provided the best evidence yet that our affinity for red meat has exacted a hefty price on our health and limited our longevity.

The study found that, other things being equal, the men and women who consumed the most red and processed meat were likely to die sooner, especially from one of our two leading killers, heart disease and cancer, than people who consumed much smaller amounts of these foods.

Results of the decade-long study were published in the March 23 issue of The Archives of Internal Medicine. The study, directed by Rashmi Sinha, a nutritional epidemiologist at the National Cancer Institute, involved 322,263 men and 223,390 women ages 50 to 71 who participated in the National Institutes of Health-AARP Dietand Health Study. Each participant completed detailed questionnaires about diet and other habits and characteristics, including smoking, exercise, alcohol consumption, education, use of supplements, weight and family history of cancer.

Determining Risk

During the decade, 47,976 men and 23,276 women died, and the researchers kept track of the timing and reasons for each death. Red meat consumption ranged from a low of less than an ounce a day, on average, to a high of four ounces a day, and processed meat consumption ranged from at most once a week to an average of one and a half ounces a day.

The increase in mortality risk tied to the higher levels of meat consumption was described as “modest,” ranging from about 20 percent to nearly 40 percent. But the number of excess deaths that could be attributed to high meat consumption is quite large given the size of the American population.

Extrapolated to all Americans in the age group studied, the new findings suggest that over the course of a decade, the deaths of one million men and perhaps half a million women could be prevented just by eating less red and processed meats, according to estimates prepared by Dr. Barry Popkin, who wrote an editorial accompanying the report.

To prevent premature deaths related to red and processed meats, Dr. Popkin suggested in an interview that people should eat a hamburger only once or twice a week instead of every day, a small steak once a week instead of every other day, and a hot dog every month and a half instead of once a week.

In place of red meat, nonvegetarians might consider poultry and fish. In the study, the largest consumers of “white” meat from poultry and fish had a slight survival advantage. Likewise, those who ate the most fruits and vegetables also tended to live longer.

Anyone who worries about global well-being has yet another reason to consume less red meat. Dr. Popkin, an epidemiologist at the University of North Carolina, said that a reduced dependence on livestock for food could help to save the planet from the ravaging effects of environmental pollution, global warming and the depletion of potable water.

“In the United States,” Dr. Popkin wrote, “livestock production accounts for 55 percent of the erosion process, 37 percent of pesticides applied, 50 percent of antibiotics consumed, and a third of total discharge of nitrogen and phosphorus to surface water.”

Finding a Culprit

A question that arises from observational studies like this one is whether meat is in fact a hazard or whether other factors associated with meat-eating are the real culprits in raising death rates. The subjects in the study who ate the most red meat had other less-than-healthful habits. They were more likely to smoke, weigh more for their height, and consume more calories and more total fat and saturated fat. They also ate less fruits, vegetables and fiber; took fewer vitamin supplements; and were less physically active.

But in analyzing mortality data in relation to meat consumption, the cancer institute researchers carefully controlled for all these and many other factors that could influence death rates. The study data have not yet been analyzed to determine what, if any, life-saving benefits might come from eating more protein from vegetable sources like beans or a completely vegetarian diet.

The results mirror those of several other studies in recent years that have linked a high-meat diet to life-threatening health problems. The earliest studies highlighted the connection between the saturated fats in red meats to higher blood levels of artery-damaging cholesterol and subsequent heart disease, which prompted many people to eat leaner meats and more skinless poultry and fish. Along with other dietary changes, like consuming less dairy fat, this resulted in a nationwide drop in average serum cholesterol levels and contributed to a reduction in coronary death rates.

Elevated blood pressure, another coronary risk factor, has also been shown to be associated with eating more red and processed meat, Dr. Sinha and colleagues reported.

Poultry and fish contain less saturated fat than red meat, and fish contains omega-3 fatty acids that have been linked in several large studies to heart benefits. For example, men who consume two servings of fatty fish a week were found to have a 50 percent lower risk of cardiac deaths, and in the Nurses’ Health Study of 84,688 women, those who ate fish and foods rich in omega-3 fatty acids at least once a week cut their coronary risk by more than 20 percent.

Ties to Cancer

Choosing protein from sources other than meat has also been linked to lower rates of cancer. When meat is cooked, especially grilled or broiled at high temperatures, carcinogens can form on the surface of the meat. And processed meats like sausages, salami and bologna usually contain nitrosamines, although there are products now available that are free of these carcinogens.

Data from one million participants in the European Prospective Investigation Into Cancer and Nutrition trial found that those who ate the least fish had a 40 percent greater risk of developing colon cancer than those who ate more than 1.75 ounces of fish a day. Likewise, while a diet high in red meat was linked to an increased risk of prostate cancer in the largeSelenium and Vitamin E Cancer Prevention Trial, among the 35,534 men in the study, those who consumed at least three servings of fish a week had half the risk of advanced prostate cancer compared with men who rarely ate fish.

Another study, which randomly assigned more than 19,500 women to a low-fat diet, found after eight years a 40 percent reduced risk of ovarian cancer among them, when compared with 29,000 women who ate their regular diets.

Personal Health – Paying a Price for Loving Red Meat – NYTimes.com.