U of M News Wire: October 4, 2007

 
    
 
A drink a day may bring the doctor your way
University of Minnesota researchers comment on a recent study linking alcohol to breast cancer

By Deane Morrison
U of M News Wire

Recent headlines bore bad news for women who drink: A large study by Kaiser Permanente doctors showed that a single daily alcoholic drink of any kind raised the risk of breast cancer by 10 percent, and three or more drinks jacked it up to 30 percent. Yet alcohol, according to other studies, may help lower the risk of heart attack. So what’s a woman to do?
 
With this question in mind, we asked University of Minnesota cancer epidemiologist Kristin Anderson and cardiologist Daniel Duprez to sort out the science behind the scoop.
 
A major finding of the study was that whether a woman drinks beer, wine, or spirits, alcohol raises her breast cancer risk the same. This came as no surprise to Anderson, a Distinguished University Teaching Professor in the School of Public Health.
 
“There have been more than 100 studies on alcohol and breast cancer,” she says. “This is consistent with past data. I was in a collaborative study by Oxford University that came out in 2002 in the British Journal of Cancer. That was a much larger study, analyzing results from 53 previous studies of 58,515 women with cancer and 95,067 without. We got similar results.” The Kaiser Permanente study was based on 70,000 patients.
 
"About 4 percent of breast cancer in developed countries is attributable to alcohol," Anderson says. "It's important to note that that is a small proportion of the disease."
 
Stories in the Minneapolis Star Tribune, the St. Paul Pioneer Press, and the New York Times have all reported the 10 percent and 30 percent increases in risk, but none reported the baseline risk. According to the American Cancer Society, U.S. women overall run one chance in eight, or 12.5 percent, of developing breast cancer and one in 34, or 2.9 percent, of dying from it.
 
Suppose for simplicity's sake that a nondrinking woman has few risk factors and a 10 percent chance of developing breast cancer. On average, such a woman who began quaffing a drink a day would raise her risk by 10 percent over the baseline, to 11 percent. If she added three drinks a day, her risk would rise from 10 to 13 percent.
 
The Star Tribune article quoted Yan Li, co-author of the Kaiser study, as saying that one possible mechanism by which alcohol could raise the risk of breast cancer is by changing the metabolism of estrogen, which promotes the growth of some breast cancers. Though not disputing that, Anderson says other factors may also play a role.
 
"Alcohol consumption has a negative impact on the absorption, utilization, and excretion of folate, a vitamin necessary for maintaining the integrity of DNA," she states. Also, alcohol may increase the activity of enzymes that activate carcinogens. And, she adds, some breakdown products of alcohol, notably a chemical called acetaldehyde, have been labeled carcinogenic.
 
According to the 2002 study Anderson took part in, "about 4 percent of breast cancer in developed countries is attributable to alcohol," she says. "It's important to note that that is a small proportion of the disease. If you live in a society that has no drinking, no cases will be attributable to alcohol."
 
The American Cancer Society estimates that in 2007 there will be approximately 178,480 new cases of breast cancer in the United States, she adds.
 
As for alcohol's role in lowering heart disease risk, Duprez says there is evidence to support it, but many questions remain. For instance, he says it is well known that alcohol increases levels of HDL--the "good cholesterol"--but nobody knows whether that is the mechanism behind the correlation between alcohol and lowered risk. Red wine has been seen as especially "protective," but it could be high levels of antioxidants in red wine or some substance in grapes that does the trick.
 
"The key is this: A maximum of one glass of alcoholic beverage a day for women and two for men is associated with cardioprotection, but this has never been shown in a randomized trial," says Duprez, an assistant professor of cardiology. "Alcohol should not be universally prescribed for health enhancement. There is a complete lack of randomized data" with respect to exactly how it might protect the heart.
 
For Anderson, the Kaiser Permanente story is an opportunity for women to think about how they live their lives.
 
"People should use this data to reflect on their lifestyle and decide if it would be prudent to change their habits," she says. "There are other risks associated with drinking more than three drinks per day. You have to look at the weight of evidence and at other studies, if possible.
 
"Most risk is at higher intakes [of alcohol]. An increase of 10 percent isn't much, but it's a real risk because it's been seen in many other studies."
 
 
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U of M researcher offers new understanding of urban sprawl
 
By Mark Cassutt
U of M News Wire

Across the United States, people moving into cities are settling on twice the amount of land as established residents, according to University of Minnesota civil engineering assistant professor Julian Marshall. His findings offer a new numerical tool for measuring urban area expansion and are featured in the September 2007 issue of Urban Studies, an international journal on urban planning and policy.
 
Determining how cities change and grow in response to population increases is a timely question.
 
“This year, for the first time in history, a majority of people will live in urban areas. In future decades, urban population growth will greatly exceed rural population growth,” Marshall said.
 
The desire new residents have for bigger homes and yards leads to even greater implications for social, health and environmental concerns associated with urban sprawl, Marshall explained.
 
Marshall analyzed U.S. census data on urban land-use and population from 1950 to 2000. “I initially found the patterns by accident, just by playing with the data,” Marshall said. He realized that from decade-to-decade, newcomers steadily stretched city borders by occupying double the land of existing residents.  
 
The researcher’s discovery was revealed while developing a new way to predict how urban areas grow over time in response to population increases. Making this prediction for a single city can be difficult, and depends on the specifics of that city such as land availability. However, when considering the growth of all cities over time, several patterns emerge. This first pattern is, as noted earlier, newcomers occupy twice the land area as existing residents. Another pattern is that the average number of people in a mile-wide strip of land across a city is constant over time. This second pattern is possible because a balance is struck between low-density urban growth at the edge of cities and new high-density housing in the urban core.
 
A third pattern builds on relationships known as “rank-size rules.” The idea is that when cities are ranked from largest to smallest, the size of each city follows a predictable proportion. For example, the population of the second-largest city is equal to one-half the largest city, and the population of the third-largest city is one-third that of the largest city, and so on. Marshall identified that similar rank-size rules hold true for other attributes of cities, such as population density and land area.
 
Marshall’s findings provide mathematical descriptions of these observations, and offer predictions regarding city sizes in future decades. Those results predict how the system as a whole behaves -- that is, distributions of values for all cities -- but not what will happen in any one city.
 
“The strength of the mathematical associations and the length of time the patterns have held (for 50 years) is surprising,” Marshall said. “I could hardly believe what I found.”
 
 
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Growing Concerns
A parenting question-and-answer column with Dr. Martha Erickson of the University of Minnesota

Question: My husband and I recently divorced and now, after four years of staying home with my son, in a few weeks I have to go back to work full-time and he will enter a childcare center. I am concerned that this transition will be really hard for my son, especially since his dad is no longer going to be living with us. What can I do to help my son get through this difficult time?
  
Answer: You’re right that this is a lot of change for a 4-year-old to handle, and I’m glad you’re able to focus on your son’s needs even in the midst of the upheaval in your own life. Although there is no way to erase the feelings of loss your son is bound to feel, there are several things you can do to ease the way for him.
 
• First, take your cues from your son’s emotions and behavior. It’s common in this kind of situation for a child to be sad or angry or both. Your son may express his feelings in words or actions (being less cooperative, for example, or acting babyish). Although you still will need to set limits on unacceptable behavior, give your son a chance to express his feelings and encourage him to put them into words. Acknowledge that you know he wishes things could be the way they used to be, and reassure him that both you and daddy are still going to take good care of him.
 
•  Since you have a few weeks before you start work, see if you can arrange for your son to get familiar gradually with the people who will care for him and, if possible, other children who attend the same childcare facility. Talk positively about the new people he will meet and the interesting things he will do, being careful not to let your own sadness or anger about the new situation color his experience. Four-year-olds often welcome the social interaction and varied activities available in childcare, so this could be a positive change for your son even though it isn’t what you had planned.
 
• In your time at home, begin to establish new rituals and traditions with your son. For example, give him your full attention while you sit down and enjoy dinner together, followed by a favorite story. Or when you first get home from work, play a game or draw pictures together. Even if it means getting up a little earlier in the morning, allow adequate time for your son to get ready and enjoy a healthful breakfast with you before going to childcare. Let him experience firsthand that his home is still a place of love, safety and comfort for him.
 
•  However hurt or angry you may be about your divorce, do everything you can to support a close relationship between your son and his father. Talk positively with your son about the times he spends with his dad and make every effort to work cooperatively with your ex-husband when it comes to childrearing. Because young children have a poorly developed sense of time and the days away from either you or dad can feel very long, encourage frequent communication between your son and his dad such as daily phone calls and hopefully your ex-husband will do the same for you when your son is with him.
 
The bottom line is that children thrive best when moms and dads can set aside their own animosity and focus together on the children’s needs. If for any reason this seems too difficult for you or your ex-husband, I urge you to seek professional help from a family counselor or mediator so that you can deal with your own issues without putting your son in the middle.
 
 
Dr. Erickson is a senior fellow and director of the Harris Programs in the Center for Early Childhood Education at the University of Minnesota
 
Want to hear more parenting advice?
Dr. Erickson and her daughter can be heard every Sunday, from 2 - 4 pm, on “Good Enough Moms,” on FM107.1 radio in the Twin Cities or via Webcast at www.FM1071.com