June 28th, 2012 by Hasham
Healthy lifestyle could prevent 40% of breast cancer cases, charity says
The estimate, by the World Cancer Research Fund (WCRF), is based on its latest review of global research linking the disease to excessive alcohol intake, lack of exercise and being overweight.
Breastfeeding babies also emerges from the study as an important means of reducing the chance of developing breast cancer – a condition that kills about 12,000 women in the UK each year.
The compilation of more than 950 research papers from around the world provides the strongest evidence so far that women’s lifestyle choices influence the risk of contracting the disease.
The report, published today, updates a major cancer prevention study released in 2007 that examined different types of cancer.
That review drew on 873 breast cancer studies. Scientists at Imperial College London have now added a further 81 studies published in the last few years.
Professor Martin Wiseman, medical and scientific adviser for the WCRF, said the expanded report “represents the clearest picture we have ever had” of how lifestyle affects a woman’s risk of breast cancer.
“This means we are now more sure than ever before that by limiting the amount of alcohol they drink, maintaining a healthy weight and being physically active, women can make a significant difference to their risk,” he said. “We estimate over 40% of breast cancer cases in the UK could be prevented just by making these relatively straightforward changes. About 45,000 women are diagnosed with breast cancer every year in the UK, so it is clear these changes could make a big difference.”
A WCRF spokesman added: “There’s very convincing evidence of the role breastfeeding plays in reducing the risk of breast cancer.
“The main messages from our last study have not changed but the evidence is stronger. We estimate that 42% of all breast cancers in the UK could be prevented through reducing alcohol consumption, exercise and [weight control].”
Patterns of the disease differ around the world. Paradoxically, China – where the population already consumes a better diet and takes more exercise – has less ability to reduce the incidence of breast cancer.
The charity recommends that both men and women aim to be as lean as possible without becoming underweight. A healthy body mass index (BMI) is between 18 and 25. The WCRF advises people to remain close to the lower end of the scale.
The charity also recommends at least 30 minutes of exercise a day and, if alcohol is drunk at all, it be limited to two drinks a day for a man and one for a woman.
The latest study on breast cancer is part of a continuous update project run by the WCRF. Bowel cancer and prostate cancer will now be studied, with updates on these due to become available in 2010.
Marilyn Gentry, chief executive of the WCRF, said: “We believe it is important that people have access to advice that is based on the latest scientific research.
“These are still quite early stages in the project but once it is fully up and running it will mean that people all over the world will always have access to up-to-date advice about how they can make lifestyle changes that can reduce their risk of cancer.”
Arlene Wilkie, director of research and policy at Breast Cancer Campaign, said: “This review provides further evidence that maintaining a healthy weight throughout life along with regular physical exercise will reduce the risk of many health problems, including breast cancer, heart disease, high blood pressure, diabetes, arthritis and other types of cancer.
“Although age is the biggest single risk factor – 80% of breast cancers are diagnosed in women over the age of 50 – being overweight after the menopause increases your risk even further.”
A Healthy Lifestyle Reduces Breast Cancer Risk for Women Either with or without a Genetic Predisposition
Women who followed weight, exercise and alcohol consumption guidelines had about the same lowered risk for getting breast cancer, even if they had a strong family history of the disease
Moderate exercise, little booze intake and holding down one’s weight might be key strategies that reduce the odds of getting breast cancer—even if a woman’s mother or sister has had the disease.
New data from 85,644 U.S. women, who were followed for an average of about five and a half years as part of the Women’s Health Initiative Observational Study, confirms earlier evidence that healthy lifestyle choices can sometimes trump genes and environment when it comes to breast cancer. The results of the study were reported online October 12 in Breast Cancer Research.
These findings are important, says Robert Gramling, an associate professor of family medicine and community and preventive medicine at University of Rochester Medical Center and a co-author of the new study, because “particularly with growing awareness of genomics, often those who have a family history of a disease that’s quite scary start thinking, ‘There’s nothing I can do to prevent it,’” he noted. “We’re beginning to find that’s not the case.” Breast cancer is responsible for the second-most cancer deaths in women (lung cancer takes the highest toll), killing some 40,170 U.S. women in 2009, according to the American Cancer Society (ACS). About 192,370 new U.S. cases are diagnosed each year.
The three lifestyle changes have each been correlated individually with reduced risk of breast cancer, but the new study looked at them as a group. The researchers asked women if they engaged in at least 20 minutes of moderate to vigorous exercise at least five days a week, limited alcohol consumption to seven glasses a week, and maintained a body mass index of 18.5 to 24.9, all of which are similar to recommendations the ACS makes for reducing risk of the disease.
Gramling and his colleagues analyzed information from women, aged 50 to 79, who had not had breast cancer themselves and who also had no close relatives with early-onset breast malignancies (before age 45).
Regardless of whether subjects had a family history of late-onset breast cancer or not, “the amount of risk reduced is exactly the same,” Gramling explains. As a measure of absolute risk, for both groups, making the healthy lifestyle choices eliminated about one case of the disease out of 1,000 each year, he notes.
“This was a very well done study,” says Catherine Carpenter an associate professor of medicine and nursing at the David Geffen School of Medicine at the University of California, Los Angeles, who was not involved in the new research. “The surprising thing was that the protection wasn’t stronger in the family history–positive women,” Carpenter says.
By excluding women with a family history of early-onset (before the age of 45) breast cancer from the study, however, the assessment might have played down the role of genetics in many cases, Carpenter notes. Late-onset “breast cancers tend to be less likely to be genetically determined,” she notes, thus leaving them more likely to be affected by lifestyle factors.
She also added that it would be useful to study whether combining these behaviors also reduces risk for women who have a family history of early-onset breast cancer.
Not all of the genetic influences are necessarily linked directly to so-called breast cancer genes. “One of the factors that is heritable and genetically determined is obesity and body mass index,” Carpenter says. “Families could inherit the predisposition to being overweight and that’s what causes breast cancer, not that they’re carrying a gene that enhances genetic susceptibility to breast cancer.”
Carpenter also notes that she is curious to know which of the three lifestyle factors had the strongest influence on preventing breast cancer, as the new study does not make a distinction among the specific behaviors and malignancy risk.
“These are very well-known behaviors that influence breast cancer,” Carpenter says. But as Gramling points out, of the healthy lifestyle recommendations, “not all the things are easy to do.” Only about 7 percent of women in the study reported following all of the lifestyle guidelines all of the time.
Untangling cancer’s roots can be a tricky business. As Carpenter explains, “These folks are more likely to have shared behavioral patterns in the family.” And getting to the bottom of cancer risk “is the major focus of genetic epidemiology in 2010,” Gramling says.
Next-step research will include more interventional studies looking at the influence of exercise and weight on a woman’s breast cancer risk. The hope of the new and the continuing research is “to better characterize how combinations of exposures contribute to women’s risk,” Gramling says, “so you can advise a woman how she can prevent breast cancer for herself.”
When in a woman’s life has the effect of diet and lifestyle on breast cancer survival been studied?
Studies of survival from breast cancer have looked at diet and lifestyle both before and after diagnosis. The examination of diet and lifestyle before diagnosis can provide information about the potential outcome of treatment and possibly the biology of cancer formation. But examination of diet and lifestyle after diagnosis has the distinct advantage that it evaluates behaviors that can be changed once a woman learns she has cancer. We discuss studies that examined diet and lifestyle before and after diagnosis separately.
Does a woman’s diet after her diagnosis with breast cancer affect her survival?
There are only two published studies that have investigated the relationship between diet after breast cancer diagnosis and survival. Although the results are promising, it is much too early to tell if these results will be confirmed until more research is done.
One extensive study examined diet after diagnosis and survival of women enrolled in the Nurses Health Study. In this study, the 1,982 women who developed breast cancer were followed an average of 13 years.
1,237 of these women had breast cancer that had not metastasized (128 of these women died during the study period). Women in this group who ate the largest amounts of poultry, total protein, and omega-3 fatty acids (from oils found in fish) had a statistically significant lower risk of death than women who ate the least amounts of these foods and nutrients. Women who ate more fiber, fish, and vegetables also had a lower risk of death than women who ate less of these food and nutrients. For the women without cancer metastases, a statistically significant higher rate of death was reported among those who ate larger amounts of hydrogenated oils found in processed baked foods (18:2 trans fatty acids).
The association of diet with survival was different for the 745 women whose cancer had metastasized (250 of these women died during the study period). Women who ate the largest amounts of dairy products and had high levels of calcium in their diets had a significantly lower risk of death. In addition, women with metastasized tumors who ate more protein, in general, had a lower risk of death. For both groups of cancer survivors, little or no association with risk of death was seen for fruits, grains, red meat, or vitamin supplements.
A second, smaller study followed 374 women with early stage breast cancer (women with no metastasized tumors beyond the lymph nodes around the breast) for eight to ten years. This study reported that postmenopausal women who ate more vegetables and who got more vitamin C from food had lower risks of death.
The effect of diet after cancer diagnosis is an area of research that calls for much more study. The results of these two studies are preliminary but they are nonetheless encouraging. Some foods or nutrients were associated with as much as a 50% decrease in the risk of death. If these results prove to be correct, they could be quite important, as diet after diagnosis is something over which cancer survivors have some control.
Is there enough evidence for a breast cancer survivor to expect to decrease her risk of death by eating more or less of some type of food?
More studies are needed before recommendations for diets for breast cancer survivors can be made. It is important to recognize that these studies are only reporting associations. The aspects of the diet that had a positive or a negative influence on survival may have had their effect by acting alone. Or, the foods may be representative of the women’s lifestyle in general. Good examples from the above studies are the changes in the risk of death reported with the highest consumption of poultry (associated with lower risk) and hydrogenated oils (associated with higher risk). Poultry products, like chicken and turkey, are often viewed as healthier choices than red meat. Women who ate more poultry may also have been making other efforts toward a healthier lifestyle. Likewise, eating more hydrogenated oils may have been something done by the women who ate more processed baked foods (where these oils are found) and who were less concerned with healthy lifestyles. The associations reported may thus reflect the overall lifestyle led by these women rather than the foods themselves.
tudies on How Lifestyle Factors May Affect Breast Cancer Risk and Recurrence
Although obesity and inactivity are associated with higher rates of postmenopausal breast cancer and poorer prognosis among breast cancer patients, increasing evidence suggests that weight loss—along with increased physical activity—reduces risk of breast cancer or its recurrence.
According to Rachel Ballard-Barbash, M.D., M.P.H., an epidemiologist at the Division of Cancer Control and Population Sciences at the National Cancer Institute, “Even though we do not yet have randomized controlled trial evidence of whether weight control and regular physical activity will lower cancer risk or extend life for breast cancer survivors, extensive data suggest that maintaining a healthy weight and exercising regularly will improve quality of life among the general population as well as breast cancer survivors.”
Weight Loss and Exercise
Although hundreds of observational studies consistently link excess weight and inactivity to higher rates of postmenopausal breast cancer and poorer prognosis in survivors, only a few studies examine whether weight loss affects cancer endpoints. According to Tim Byers, M.D., M.P.H., of the Colorado School of Public Health in Aurora, in a recent review article, that’s because intentionally losing weight and keeping it off is relatively uncommon. However, a few large studies on bariatric procedures, which involve surgically reducing the size of the stomach, suggest that weight loss is associated with lower cancer risk. After nearly 11 years of follow-up, a Swedish study found that women undergoing the surgery had a 42% lower overall cancer risk and a 31.9% …