What is Obesity?

The National Institute of Health measures obesity by a formula called the body mass index (BMI). BMI is the ratio of one’s weight in kilograms to one’s height in meters. Adults over the age of 20 can be classified into 4 groups:

• Less than 18.5 BMI – Underweight
• 18.5-25 BMI – Normal
• 25-30 BMI – Overweight
• 30+ BMI – Obese

This chart helps determine your BMI. Find your height on the left or right side and your weight on the top or bottom. The point where these lines intersect reveals the category you fall in. You can also use the calculator below to find your body mass index. Obese individuals have a BMI of over 30.

[Chart courtesy of Wikimedia Commons]

[Calculator courtesy of CDC (Centers For Disease Control & Prevention)]

Who Is At Risk For Obesity?

Anyone is at risk for obesity. Obesity is, in fact, becoming more and more common in the U.S. According to the 2007–2008 National Health and Nutrition Examination Survey (NHANES), over one-third (33.8%) of the U.S. adult population aged 20-74 are obese. This rate shows an alarming upward trend from the 13.4% rate in the 1960-1962 survey and the 22.9% rate in the 1988-1994 survey. In 2007-2008, Mexican-American women (45.1%) and African-American women (49.6%) had a significantly higher rate of obesity. Common traits of those who are obese are a high-calorie diet and an inactive lifestyle.

How Obesity Increases Breast Cancer Risk: The Alarming Facts

A growing number of studies have shown a undeniable link between obesity and an increased risk of breast cancer. According to peer-reviewed medical studies compiled by the National Cancer Institute:

• Obesity and physical inactivity may account for 25 to 30 percent of postmenopausal breast cancer
• Preventing weight gain can reduce the risk of many cancers
• Even a weight loss of only 5 to 10 percent of total weight can provide health benefits
• 3.2 percent of all new cancers are linked to obesity
• In 2002, about 41,000 new cases of cancer in the United States were estimated to be due to obesity
• A recent report estimated that, in the United States, 14 percent of deaths from cancer in men and 20 percent of deaths in women were due to overweight and obesity
• After menopause, obese women have 1.5 times the risk of breast cancer of women of a healthy weight
• Scientists estimate that about 11,000 to 18,000 deaths per year from breast cancer in U.S. women over age 50 might be avoided if women could maintain a BMI under 25 throughout their adult lives
• Weight gain during adulthood has been found to be the most consistent and strongest predictor of breast cancer risk in studies in which it has been examined
• Women with a large amount of abdominal fat have a greater breast cancer risk than those whose fat is distributed over the hips, buttocks, and lower extremities
• Both the increased risk of developing breast cancer and dying from it after menopause are believed to be due to increased levels of estrogen in obese women; estrogen levels in postmenopausal women are 50 to 100 percent higher among heavy versus lean women
• Because breast tumors are more difficult to detect in obese women, breast cancer is more likely to be detected at a later stage than lean women, leading to a higher breast cancer mortality rate for obese women
• African-American women who have a high BMI are more likely to have an advanced stage of breast cancer at diagnosis
• Obese Hispanic white women were twice as likely to develop breast cancer as non-obese Hispanics

How Can I Reduce My Risk of Obesity & Breast Cancer?

If you are at a healthy weight already, maintain it. Periodically weigh yourself and be aware of lifestyle changes such as a new job, pregnancy, or a change in activity level that might effect your calorie expenditure or intake. Adjust your eating and exercise habits to allow for the changes.

If you are overweight or obese, it is never too late to lose weight. Ignore fad diets. Follow proven weight loss guidelines (eat less, exercise more) for long-lasting weight loss that will help reduce your risk of breast cancer. Consider eating more anti-cancer foods, many of which are low-calorie. Begin a workout schedule and eat less.

No matter what your weight, reduce your overall cancer risk by learning about the other risk factors for breast cancer, many of which are preventable.

Few studies have evaluated the combined impact of following recommended lifestyle behaviors on cancer, cardiovascular disease, and all-cause mortality, and most of those included tobacco avoidance as one of the recommendations. Because eight in ten Americans are never or former smokers, researchers wanted to more clearly understand the impact of other recommended behaviors. For their study, researchers led by Marji McCullough at the American Cancer Society used diet and lifestyle questionnaires filled out in 1992 and 1993 by 111,966 non-smoking men and women in the Cancer Prevention Study (CPS)-II Nutrition Cohort. The participants were scored on a range from 0 to 8 points to reflect adherence to the American Cancer Society (ACS) cancer prevention guidelines regarding body mass index, physical activity, diet, and alcohol consumption, with 8 points representing adherence to all of the recommendations simultaneously.

After 14 years, men and women with high compliance scores (7, 8) had a 42% lower risk of death compared to those with low scores (0-2). Risk of cardiovascular disease death were 48% lower among men and 58% lower among women, while the risk of cancer death was 30% lower in men and 24% lower in women. Similar associations, albeit not all statistically significant, were observed for never and former smokers.

The researchers conclude that adhering to cancer prevention guidelines for obesity, diet, physical activity, and alcohol consumption is associated with lower risk of death from cancer, cardiovascular disease, and all-causes in non-smokers. They say beyond tobacco avoidance, following other cancer prevention guidelines may substantially lower risk of premature mortality in older adults.

Sources

Article: “Following cancer prevention guidelines reduces risk of cancer, cardiovascular disease and all-cause mortality.” Marjorie L McCullough, Alpa V Patel, Lawrence H Kushi, Roshni Patel, Walter C Willett, Colleen Doyle, Michael J Thun, and Susan Gapstur. Cancer Epidemiol Biomarkers Prev April 5, 2011; Published OnlineFirst April 5, 2011; doi:10.1158/1055-9965.EPI-10-1173 [ABSTRACT]

"Since 1-in-6 women who die from breast cancer are diagnosed in their 40s, we simply cannot afford to see missed opportunities for earlier detection" Palmaro said. "Scientific evidence, including data from British Columbia, shows that screening women in their 40s through organized programs can help to save lives."

Strong scientific evidence and public demand exists for screening Canadian women aged 40-49 for breast cancer, the Canadian Breast Cancer Foundation (CBCF) said today in response to new screening guidelines released by the Canadian Task Force on Preventive Health Care.

“The fact is scientific evidence demonstrates that earlier detection and diagnosis can save lives among women 40-49 by at least 25%,” said Sandra Palmaro, CEO, Canadian Breast Cancer Foundation – Ontario Region.

Palmaro added that screening can help find cancers that are smaller and haven’t spread, which can allow for better treatment options and reduced disability and death from breast cancer. Breast cancer continues to be the most frequently diagnosed cancer among Canadian women.

One of CBCF’s most significant concerns about the Task Force report is that it relied heavily on old data from “randomized controlled trials” (RCT’s) related to breast cancer screening and mammography, some of which are 25 – 40 years old and were based on equipment that is now outdated. There has been an enormous change in breast imaging since that time, including significant improvements to analog technology, and the continued adoption of digital mammography across Canada. Digital mammography has been shown to increase accuracy in younger women pre and perimenopausal women, and women with dense breasts, the group the Task Force recommends be excluded.

“This undermines the scientific basis for the Task Force’s conclusions,” said Dr. Martin Yaffe of Sunnybrook Research Institute. “Screening technology is significantly more sophisticated and accurate at detecting breast cancer today than it was when those studies were done.”

Dr. Yaffe chaired a Scientific Advisory Committee during the CBCF It’s About Time conference that included in its review more recent observational studies from Europe and Canada. The conference’s It’s About Time report issued in October, 2010, concluded that there are benefits of screening women in their 40′s that include savings lives through earlier diagnosis.

“All RCTs have limitations due to non-compliance (when women invited to be screened decline) and contamination (when women in the control group have mammography outside the trial) and therefore RCTs also underestimate the benefits of screening,” says Dr. Paula Gordon of BC Women’s Hospital.

“It’s critically important to consider these issues in the context of today’s technology and in terms of the real life experiences of Canadian women. That evidence strongly supports screening women beginning at age 40,” said Gordon. “Our own data from BC show 25-39% mortality reduction among screened women aged 40-49. And these data were derived even before widespread implementation of digital mammography.”

CBCF is encouraging the six provinces and territories where women 40-49 are not eligible to participate in their organized screening program – Ontario, Manitoba, Newfoundland and Labrador, New Brunswick, Quebec and Saskatchewan – to take a first step in allowing women 40-49 access to organized screening programs where possible and if recommended by a health care provider. This is the current practice in Alberta while in BC, Nova Scotia, PEI, Northwest Territories and Yukon women do not require a health care provider’s recommendation to participate in organized screening programs.

CBCF’s position is also consistent with the breast cancer screening guidelines from the National Cancer Institute, the American Cancer Society, and the American College of Obstetricians and Gynecologists, all of which recommend that women begin screening at 40 years of age.

“Since 1-in-6 women who die from breast cancer are diagnosed in their 40s, we simply cannot afford to see missed opportunities for earlier detection” Palmaro said. “Scientific evidence, including data from British Columbia, shows that screening women in their 40s through organized programs can help to save lives.”

While all screening tests, including mammography, have both benefits and limitations, Canadian women appear to be more concerned about being thoroughly-tested than the possibility of a false alarm. A recent Canadian survey conducted by Strategic Communications Inc, sought the views of 1,670 women on the topic of breast cancer screening.

When surveyed, women were provided information about the potential for “false positives” during screening and what the outcomes of those results could be, 87.5 per cent of respondents still felt organized screening for women 40-49 offered either “much more benefit” or “more benefit” than limitation.

The survey found that if offered the choice between two theoretical screening tests:

A majority (63 percent) of Canadian women would choose a screening test that “never misses cancer but 1-in-10 tests are false alarms.” Only 20 per cent would choose a test that “misses 1-in-3 cancers but gives no false alarms.” CBCF encourages women to make an informed decision about breast cancer screening by learning about the benefits and limitations of screening and to speak with a health care provider about what is right for them.

“While recognizing governments’ need to make prudent budget decisions and the need for women over age 50 to continue to have full access to organized screening, CBCF believes we should work toward all Canadian women aged 40-49 participating in provincial and territorial organized breast cancer screening programs with a healthcare provider’s recommendation,” Palmaro said.

•    Precancerous cells that consume sugar more common in this population.
•    Prediabetes or gestational diabetes could speed development of cancer cells.

Certain cancer signaling pathways that are activated in aggressive cancer can be detected very early, even in precancerous cells, among young African-American women at high risk for breast cancer. This may allow for earlier detection and prevention of cancer.

However, the early activation of these pathways, which are linked to how the body’s cells consume and break down sugar, also raise the concern that certain conditions such as gestational diabetes and prediabetes, where the body produces more sugar, might stimulate precancerous cells promoting a conversion into cancerous cells.

Victoria L. Seewaldt, M.D., presented these study results at the Fourth AACR Conference on The Science of Cancer Health Disparities, held Sept. 18-21, 2011, in Washington, D.C.

“We see a lot of very aggressive triple-negative breast cancers among young African-American women and a very high death rate, with only 14 percent alive at five years,” explained Seewaldt, professor of medicine and co-director of the breast and ovarian cancer program at Duke University in Durham, N.C. “We wanted to figure out why this was occurring among these women.”

It was already known that aggressive cancer cells actively consume glucose and produce lactic acid, even in the presence of adequate oxygen. Seewaldt and colleagues said this shift toward lactate production is called the Warburg effect.

“One of the hallmarks of really aggressive cancers is that they start taking sugar, breaking it down and turning it into energy,” she said. “It becomes their primary source of energy and that allows the cancer cells to grow rapidly.”

Although the Warburg effect is normally assumed to be a late event in breast cancer, previous research indicated that this process occurs early, even during cancer initiation, in high-risk African-American women. Because this process is occurring earlier, the researchers theorized that they could test for it in young African-American women as a method of breast cancer prevention.

Seewaldt and colleagues looked at two independent groups of 39 and 38 high-risk premenopausal African-American women. High-risk women were normally those women who had mothers or sisters who died from breast cancer at an early age, according to Seewaldt.

“We found that in a high proportion of high-risk African-American women these precancerous cells were taking in a high amount of glucose, and they also had activation of insulin signaling,” she said. “In these women, we would worry that if they developed gestational diabetes that the condition could really stimulate precancerous cells.”

Luckily, conditions like obesity and gestational diabetes can be avoided or treated, said Seewaldt.

“Exercise, weight loss and the diabetes drug metformin provide important opportunities for preventing aggressive breast cancer in African-American women. These are things where a community approach could really make a difference,” she said.

[Photo by bodytel]

Using breast magnetic resonance imaging (MRI) screenings among targeted, high-risk, underserved women significantly decreased diagnostic cost and increased patient compliance rates with follow-up compared to using general risk mammography screenings.

However, a caveat to these findings was that the cost of a MRI was reduced from an average of $3,500 to $649 by a grant specific to the study. Cost per diagnosis was $37,375 for mammography compared to $21,561 for MRI at the grant-based rate, according to the researchers.

“What we need is to lower the cost of MRI, and maybe that will happen as we do more of them,” said lead researcher Anne C. Ford, M.D., assistant professor in obstetrics and gynecology at Duke University Medical Center.

Preliminary results of the study, conducted by Ford and colleagues from 2004 to 2011, were presented at the Fourth AACR Conference on The Science of Cancer Health Disparities, held in Washington, D.C., from Sept. 18-21, 2011.

The researchers compared breast cancer mammography screening in 299 general-risk, underserved women to MRI screening in 299 high-risk, underserved women. Women with abnormal mammogram or abnormal breast MRI underwent ultrasound, ultrasound guided biopsy and/or stereotactic biopsy for mammogram cases, and/or MRI guided biopsy for MRI cases.

Results showed that mammographic screenings detected one breast cancer case, while MRI screenings detected nine cases. Benign breast/total biopsies were found in 88 percent of mammographic screening cases and in 78 percent of MRI cases.

“In an underserved population, using this model, it is cost effective to screen with MRI because we found more breast cancers with MRI than we did with mammography in this population,” Ford said. “If you truly target high-risk women with MRIs, you can find the cancers, and you can find them early.”

In addition, compliance with follow-up in mammographic screenings was 75 percent and 90 percent in MRI screenings. Vital to those results was the utilization of a breast navigation team, which recruited study participants from the general population at health and screening fairs in central North Carolina, according to Ford.

“The navigation team was key in helping the women — and these are all uninsured or under-insured women — negotiate the medical center,” she said.

The first talk, an epidemiological perspective on the causes and prevention of breast cancer was given by Dr. Valerie Beral, University of Oxford, Oxford U.K. Her talk discussed the areas of child bearing, lactation and nutrition.  She believes that cultural differences in these areas account for the international disparities in breast cancer incidents between the developed and developing countries.

Dr. Beral discussed alcohol, height, body mass and age at menarche and its relationships to breast cancer. She mentioned that there’s really nothing one can do about their height and menarche, however one has control over their alcohol intake and body mass. I happen to feel that the age of menarche may be altered by increasing the activity level of our children from the time they are able to walk which could possibly have an impact on the epidemic of childhood obesity we’re currently facing as well as impact heart cancer risks.

As far as child bearing is concerned, Dr. Beral introduced fascinating facts beyond age at first birth. She clearly stated that number of births and the length of breast feeding are also important factors. So the earlier the age at first birth, the more children one bears, and the longer one breast feeds potentially can reduce the risk of breast cancer.  This is why so many women in developed countries are at a higher risk for developing breast cancer.  We are at an older age when we give birth to our first child, we tend to have fewer children, and we breast feed for a shorter period of time.  She also said that while a woman is taking hormone replacement therapy (HRT) or oral contraceptive pills her risk for breast cancer is increased but this increased risk is lost approximately 4-5 years after a woman discontinues using HRT or birth control pills.

In summary Dr. Beral states “it is neither desirable nor feasible for women to revert to childbearing patterns of the past to prevent breast cancer. If we want sizable reductions in breast cancer incidence we need to develop an appropriate way of mimicking the effects of child bearing on the breasts.” Perhaps it will be possible to develop a short term “hormonal” vaccine to provide long term protection against breast cancer.

Virginia E. Maurer, MD
Diseases of the Breast

More interesting facts by Dr. Beral

• In developed countries 10% of women by the age of 80-85 will have breast cancer.
• In the USA this year 180,000 women developed breast cancer.
• To afford women a 20% reduction in breast cancer one would have to eliminate obesity, alcohol and hormone replacement therapy.

Stay tuned for more of Dr. Maurer’s thoughts on the 32nd Annual San Antonio Breast Cancer Symposium…

Most recent data shows that 17% of breast cancer deaths happened in women who were diagnosed in their 40s, and 22% occurred in women diagnosed in their 50’s. In terms of cost-effectiveness, practical use, and precision, digital mammography is the best screening tool for the early detection of breast cancer.  To limit its use will mean that breast cancers will go undiagnosed for a longer period of time.  Early detection often allows for breast conserving surgery and possible avoidance of chemotherapy. The limitation of an annual digital mammography screening potentially crushes these options for women 40-49.

Like the American Cancer Society I will continue to recommend annual screening using digital mammography to all women beginning at age 40 and clinical and breast self examinations for women beginning at the age of 18. There is no known cure for breast cancer, though the earlier it is caught increases a woman’s chance of survival. A breast self-exam is not a diagnostic practice but a tool that encourages a woman to recognize any changes that may occur in her breast; a clinical examination allows an expert to confirm any suspicious changes and a digital mammography enhances visibility by up to 300% making it more likely to see lumps and other abnormal changes that may be present in the breast tissue. Women need to fight this disease from a position of strength and knowledge and advocate for their own health with these three components of early detection. Breast cancer is a major health problem to too many women; a digital mammography screening reduces breast cancer mortality and saves lives.

Here at the Maurer Foundation our message has always been that breast cancer happens 365 days a year not just during the month of October. As we enter into breast cancer awareness month, you will be hearing a lot of new information. Always remember to take the time to do your research and contact us if you have any questions.