• Weight, lack of exercise raise risk of colorectal cancer

    By Catherine Winters, MyHealthNewsDaily 

    The heavier a person is and the less exercise he or she does, the greater the likelihood of developing a specific type of colorectal cancer, a new study finds.

    Researchers at the Dana-Farber Cancer Institute in Boston analyzed data on weight and physical activity from questionnaires sent every two years to more than 109,046 women who participated in the landmark Nurses' Health Study, an ongoing study about women's health that is following nurses. The questionnaires also went to more than 47,684 men who participated in the Health Professionals Follow-Up Study, an ongoing study about men's health that includes more than 50,000 men who work in health care. Data collection began in 1976 for the women and in 1986 for the men.

    When follow-up ended in June 2004, 2,263 cases of colorectal cancer — 842 in men and 1,421 in women — had been diagnosed.  The researchers analyzed 861 of the cancers to determine if any contained a molecular biomarker, called CTNNB1, which has been linked to cancer and obesity. Fifty-four percent of the tumors were CTNNB1-negative and 46 percent were CTNNB1-positive.

    Researchers next examined how body mass index, or BMI, and physical activity levels affected a person's risk of developing CTNNB1-negative or CTNNB1-positive colorectal cancer. What they found: The higher a person's BMI, the greater the likelihood he or she would develop a CTNNB1-negative cancer. Each 5.0 kg increment in BMI — about 11 pounds — was associated with a 34 percent higher risk for CTNNB1-negative colorectal cancer, said lead study author Shuji Ogino, an associate professor of pathology at Dana-Farber Cancer Institute in Boston.

    By contrast, the more physical activity a person did, the lower the risk for CTNNB1-negative colon cancer. Study participants did aerobic activities such as walking (at a usual pace), jogging, running, bicycling, swimming laps, playing racquet sports and lower-intensity activities such as yoga, toning and stretching.

     Each exercise was assigned a metabolic equivalent task (MET) score, which is a measure of exercise intensity. The higher the MET score, the more calories an activity burns.  For example, sitting quietly is the equivalent of one MET; walking at a pace of 1 to 2 miles per hour is the equivalent of about 2 METS; slow jogging is about 6 METS; cycling at less than 10 mph is about 4 METS; swimming moderately fast to fast laps is about 6 to 10 METS; and running approximately six miles per hour is about 10 METS.

    In the study, every 10 METs per hour increase in physical activity was associated with a 7 percent reduction in the risk for CTNNBI-negative colorectal cancer. People who accumulated about 18 MET hours per week in exercise, saw approximately a 20- to 30- percent reduction in risk, said Ogino, who is also an associate professor in the department of epidemiology at the Harvard School of Public Health.  That's the equivalent of about 30 minutes of moderate-intensity physical activity on most days of the week.

    Neither BMI nor physical activity level was associated with CTNNB1-positive cancer.

    Previous research has shown that doing regular physical activity and maintaining a healthy weight are associated with a decreased risk of colorectal cancer, but it has been unclear why. "We now have a biomarker we can subtype," Ogino said "No other prospective study has found this."

    Just how BMI and exercise affect the risk of CTNNB1-negative cancer is unclear. One theory is that higher circulating levels of insulin and insulin-like growth factor in people who are heavy or who are physically inactive may promote cancer cell survival and proliferation.

    Currently, there is no way to accurately measure risk for CTNNB1-negative colorectal cancer. That said, Ogino recommends doing regular physical activity to reduce the overall risk for colorectal cancer. "Physical activity is more easily controlled than body weight," he said. "Physical activity is easy to incorporate into your life and hopefully it will decrease weight, too."

     Not counting skin cancer, colorectal cancer is the third most common cancer diagnosed in American men and women. Overall, people have a 1 in 20 lifetime risk of developing the disease.

    According to the American Cancer Society, an estimated 102,480 new cases of colon cancer and 40,340 cases of rectal cancer will be diagnosed in 2013. Some 50, 830 people will die from colorectal cancer.

    The study is published today (Feb. 26) in the journal Cancer Research.

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  • Lightest, heaviest fetuses have highest stillbirth risk

    By MyHealthNewsDaily.com staff

    Stillbirths are more common among the heaviest and lightest fetuses, according to a new study from Canada.

    Researchers found that 19 percent of all stillbirths occurred in fetuses whose weight put them in the lightest 10 percent of all fetuses of their age, with 6 percent of stillbirths occurring in the lightest 1 percent.

    Fetuses among the heaviest 1 percent of those their age accounted for another 1 percent of all stillbirths.

    “Extreme underweight and overweight states confer the highest risk of stillbirth," the researchers wrote.

    Stillbirth  is commonly defined as death of a fetus after 23 weeks pregnancy and after the fetus weighs 500 grams (about 1.1 pounds); in this study, the researchers included fetal deaths that occurred after 20 weeks of pregnancy. The researchers collected data on all births in Ontario between 2002 and 2007 — a total of 767,016 live births and 4,697 stillbirths.

    Problems with the placenta can result in a fetus being severely underweight, while fetuses are most at risk for being overweight  if the mother is obese or has diabetes, according to the researchers.

    The researchers say their finding may help doctors assess when it might be appropriate to deliver a baby early, in cases where the chance of it surviving outside the womb might be higher than the chance surviving in the womb.

    In the developed world, stillbirth s occur in 6 out of 1,000 births — a rate that is higher than the infant death rate from conditions such as sudden infant death syndrome or complications of premature birth, the researchers said.

    The research was published yesterday (June 25) in the Journal of Perinatology.

    Pass it on: Low or high fetal weight increases the risk of stillbirth.

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  • Report: World's population is 17 million tons overweight

    By Alastair Jamieson, msnbc.com

    Obesity is threatening the world’s future food security, according to a study published Monday that calculated the weight of the global population at 316 million tons.

    Researchers from the London School of Hygiene and Tropical Medicine said increasing levels of fatness around the world could have the same impact on global resources as an extra half a billion people.

    In a report published in the journal BMC Public Health [PDF file here], the researchers estimated that 17 million tons of the global body mass was due to people being overweight.

    Despite only making up five per cent of the world's population, the United States accounts for almost a third of the world's weight due to obesity, the researchers found.

    In contrast, Asia has 61 per cent of the world's population but only 13 per cent of the world's weight due to obesity.

    When working out is too much of a good thing 

    The study is published to coincide with the largest-ever United Nations conference, Rio+20, which will discuss sustainable development.

    Using World Health Organization data from 2005, the scientists calculated the average global body weight at 137 pounds, but in North America the average was 178 pounds.

    Get off your butt and exercise, orders your doc 

    One of the authors of the paper, Professor Ian Roberts, told the BBC: "When people think about environmental sustainability, they immediately focus on population. Actually, when it comes down to it, it’s not how many mouths there are to feed, it is how much flesh there is on the planet."

    "If every country in the world had the same level of fatness that we see in the USA, in weight terms that would be like an extra billion people of world average body mass," he added.

    Roberts said health campaigns and urban design that promotes walking or cycling were among the best ways to tackle the problem, which was primarily caused by sedentary modern lifestyles.

    “We do not move our bodies so much but we are biologically programmed to eat,” he told the Daily Telegraph. "We often point the finger at poor women in Africa having too many babies. But we've also got to think of this fatness thing; it's part of the same issue of exceeding our planetary limits."

  • Thin patients have higher risk of dying after surgery

    By  Rachael Rettner
    MyHealthNewsDaily

    While being trim is generally good for your health, it may actually raise the risk of death after surgery, recent research suggests.

    In one study, slender people with a body mass index (BMI) of 23 or less were 40 percent more likely to die within a month of a surgical procedure, compared with those who were overweight, with a BMI between 26 and 29, the researchers said.

    The results held even after the researchers took into account the condition the patient had that required surgery, and the risk of death associated with that surgery.

    That study is published in the March issue of the journal Archives of Surgery.

    The findings agree with those of several other recent studies. In a study published last week in the Journal of Cardiothoracic and Vascular Anesthesia, 20 percent of underweight patients who had coronary artery bypass surgery died in the hospital, compared with 3 percent of obese patients (though the researchers noted far fewer patients in the study were underweight).

    And in a study published in February in the journal Colorectal Disease, low BMI was a risk factor for dying after colon surgery.

    Low BMI should be recognized as an important risk factor for death following surgery, study researcher George Stukenborg, of the University of Virginia’s School of Medicine, said in an interview with MyHealthNewsDaily in November. Doctors should take into account thinness when planning a patient's care after surgery, and should tell thin patients about their increased risk of death, Stukenborg said.

    Death after surgery
    In their study, Stukenborg and colleagues analyzed information from more than 189,500 patients from 183 medical centers who underwent surgery between 2005 and 2006.

    The researchers divided patients into five groups based on BMI. They calculated the risk of death for each group, as compared with the risk of death for those in the middle group (who had a BMI between 26.3 and 29.7).

    About 3,200 patients died within 30 days of surgery. Among those with a BMI of 23.1 or less, 2.8 percent died within 30 days, whereas 1.5 percent of patients with a BMI between 26.3 and 29.7 died.

    There was no difference in the risk of death between patients who were overweight, and patients who were obese or very obese, the researchers found.

    Why the link?
    This study cannot tell us why thin people are at an increased risk of death after surgery, Stukenborg said. One idea is that these patients may be more frail, or may have recently experienced weight loss, Stukenborg said.

    In the study published last week, underweight patients were at higher risk of intestinal bleeding, pneumonia, a prolonged stay in the intensive care unit and need for a blood transfusion compared with those who were obese.

    People with a BMI of under 18.5 are generally considered underweight, and in the studies, they were included with patients who had BMIs between 19 and 24, who were of normal weight.

    People who fall along the extremes of the weight spectrum, both underweight and morbidly obese, are at increased risk for complications after surgery, said Dr. Nestor de la Cruz-Munoz, chief of bariatric surgery, University of Miami School of Medicine. Underweight people likely represent a sicker population with underlying medical conditions, de la Cruz-Munoz said.

    "As soon as you drop below your ideal weight, you get into a group of people who are malnourished," and not well in general, de la Cruz-Munoz said. People in this population may not have adequate levels of protein in their bodies to properly heal in areas that have been operated on, he said.