(Washington Post Staff Photo/Andrea Bruce) 
 
 Just one glass of wine or other alcoholic drink a day significantly raises the risk of breast cancer, while vigorous exercise such as running and bicycling reduces it, according to an expansive review of research on the effects of diet, nutrition and physical activity on the disease. 
 
 The report, which was issued Tuesday, concluded that drinking the equivalent of one small glass of wine, beer or other alcohol a day — about 10 grams of alcohol — is linked to an increased cancer risk of 5 percent for pre-menopausal women and 9 percent for post-menopausal women. A standard drink has 14 grams of alcohol. 
 
 "This suggests there is no level of alcohol use that is completely safe in terms of breast cancer," said Anne McTiernan, a cancer-prevention researcher at Fred Hutchinson Cancer Research Center in Seattle and one of the report's lead authors. "If a woman is drinking, it would be better if she kept it to a lower amount." 
 
 The review, by the American Institute for Cancer Research (AICR) and the World Cancer Research Fund, evaluated research in 119 studies encompassing data on 12 million women from around the world. It is the first such review since 2010, the groups said. 
 
 For the first time, researchers concluded evidence is strong that vigorous exercise reduces breast-cancer risk. Pre-menopausal women who were the most active had a 17 percent lower risk of developing malignancies compared to the least active women, while post-menopausal women had a 10 percent decreased risk. 
 
 [For women, heavy drinking has been normalized. That's dangerous.] 
 
 The researchers noted that many things influence cancer risk and that women can't control factors such as a family history of cancer. But, McTiernan said, "having a physically active lifestyle, maintaining a healthy weight throughout life and limiting alcohol — these are all steps women can take to lower their risk." 
 
 At the same time, she said, a healthy lifestyle is not a guarantee. Rather, it's more like wearing a seat belt. Many women will do everything they can to reduce their risks of breast cancer but still get diagnosed. "That's unfortunate, but that's what happens," she said. 
 
 Researchers were not able to calculate the degree to which vigorous exercise might cut the risk of alcohol consumption. What happens, for example, if a regular drinker also runs daily? 
 
 "The mechanism suggests that it could be helpful," McTiernan said. Alcohol increases estrogen, which is linked to increased breast-cancer risk, while physical activity reduces it. "But I can't say that for someone who drinks five drinks and then runs, that the exercise is going to negate the adverse effects of the alcohol." 
 
 The report found women who are overweight or obese have a higher risk of post-menopausal disease. 
 
 "If women lose just 10 percent of their weight, it's linked to reduced blood estrogen, inflammation" and other factors associated with breast cancer, McTiernan said. 
 
 The report also found limited evidence linking dairy foods, diets high in calcium and foods containing carotenoids to a lower risk of some breast cancers. Carotenoids include such fruits and vegetables as kale, apricots and carrots. 
 
 About 252,000 women in the United States are expected to be diagnosed with breast cancer this year. AICR estimates that 1 in 3 cases could be prevented if women did not drink alcohol, were physically active and maintained a healthy weight. 
 
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 HealthDay Reporter 
 
 WEDNESDAY, Aug. 28 (HealthDay News) -- Drinking even one alcoholic drink a day in the years before a woman's first pregnancy can increase her risk of breast cancer later in life, according to a large new study. 
 
 Other research has linked alcohol consumption to increased breast cancer risk, as well as finding that delayed childbearing can increase breast cancer risk. 
 
 The new research is thought to be the first to focus on the effect of alcohol intake during the time frame between the start of menstruation and a first pregnancy, the researchers said. 
 
 "The risk increased by 11 percent for every 10 grams a day of intake, about six drinks per week," said study author Dr. Ying Liu, an instructor of public health sciences at Washington University School of Medicine, in St. Louis. "These risk values were estimated as compared with nondrinkers." 
 
 "One drink was defined as one bottle or can of beer, a 4-ounce glass of wine or a shot of liquor," Liu said. 
 
 Drinking about one drink a day also increased the risk for proliferative benign breast disease, a risk factor for breast cancer, by about 16 percent, according to the study, which was published Aug. 28 in the Journal of the National Cancer Institute. 
 
 The researchers analyzed data from more than 91,000 women who took part in the Nurses' Health Study II who had no cancer history when they began. They answered questions on alcohol consumption in 1989 and were followed through 2009 to analyze their risk of breast cancer. 
 
 The new study also looked at whether the women contracted benign breast disease, and whether alcohol may have played a role in that condition, in a subgroup of more than 60,000 women who were evaluated from 1991 through 2001. 
 
 The researchers found more than 1,600 cases of breast cancer and 970 diagnoses of benign breast disease during the study period. 
 
 Drinking alcohol after the first menstrual period and before the first pregnancy was linked with a risk of both, regardless of whether a woman drank after the first pregnancy. The link held after accounting for multiple other risk factors, including family history of breast cancer. 
 
 The more the women drank, the higher their risk. 
 
 The researchers, however, found only a link between pre-pregnancy drinking and breast cancer risk, not a cause-and-effect relationship. 
 
 "Breast tissues are particularly susceptible to environmental exposures between [the onset of menstruation] and first pregnancy because they undergo rapid cellular proliferation," Liu said. During pregnancy, however, other cellular changes make the breast tissue less susceptible to cancer. 
 
 "Our results suggest that alcohol intake before the first pregnancy consistently increases the risk of breast cancer and the risk of proliferative [benign breast disease]," Liu said. She speculated that the benign breast disease may be a pathway linking drinking in early life and breast cancer, ''but not the only route." 
 
 It is crucial to put the 11 percent increased risk in perspective, said Dr. Laura Kruper, co-director of the breast cancer program and director of the Cooper Finkel Women's Health Center at the City of Hope Cancer Center in Duarte, Calif. 
 
 Overall, a woman's lifetime risk of breast cancer is about one in eight, or 12 percent. "If you take the baseline risk -- 12 percent -- and increase that by 11 percent, it is about 13 percent," Kruper said. 
 
 Liu said the one-in-eight statistic includes both drinkers and nondrinkers, but she did not know of a statistic for lifetime breast cancer risk for nondrinkers. 
 
 So although the study did find an increased risk, Kruper said, "I think the real take-home point is the more you drink the more you increase risk." 
 
 The research is another call for moderation, Kruper and Liu agreed. Liu said all women in the age category she studied "should reduce their drinking to less than one drink a day, especially before first pregnancy, to reduce their breast cancer risk." 
 
 More information 
 
 To learn more about risk factors for breast cancer, visit the American Cancer Society. 
 
 Copyright © 2012 HealthDay. All rights reserved. ||||| (CNN) Compared with women who have never had children, women who have given birth may have an increased breast cancer risk that continues for up to 23 years after their most recent birth, according to a new study published in the journal Annals of Internal Medicine on Monday. 
 
 "What we saw was this pattern where risk was highest about five years after birth, and then it gradually declined as time went on," said Hazel Nichols, an assistant professor of epidemiology at the University of North Carolina at Chapel Hill's Gillings School of Global Public Health , who was first author of the study. 
 
 Yet beyond those 23 years, the risk seems to change so that childbirth then appears to be protective against breast cancer, according to the study. 
 
 Still, experts warn that women should not worry and that the risk is small. 
 
 Undergoing a breast cancer screening, during which your breasts are checked before any signs or symptoms emerge, cannot prevent cancer -- but it can find the disease early. Experts advise talking to your doctor about which breast cancer screening tests and guidelines are right for you. 
 
 Undergoing a breast cancer screening, during which your breasts are checked before any signs or symptoms emerge, cannot prevent cancer -- but it can find the disease early. Experts advise talking to your doctor about which breast cancer screening tests and guidelines are right for you. 
 
 If you are taking or have been told to take hormone replacement therapy, experts recommend talking to your doctor about associated breast cancer risks. Some studies suggest that using combination hormone therapy for more than three to five years increases the risk of breast cancer. 
 
 If you are taking or have been told to take hormone replacement therapy, experts recommend talking to your doctor about associated breast cancer risks. Some studies suggest that using combination hormone therapy for more than three to five years increases the risk of breast cancer. 
 
 Controlling your weight and eating a Mediterranean-style diet has been associated with a reduced risk of breast cancer. Being overweight or obese increases the risk of breast cancer. 
 
 Controlling your weight and eating a Mediterranean-style diet has been associated with a reduced risk of breast cancer. Being overweight or obese increases the risk of breast cancer. 
 
 The more alcohol you consume, the greater your risk of developing breast cancer, research suggests. The Centers for Disease Control and Prevention recommends limiting alcoholic drinks to one per day. 
 
 The more alcohol you consume, the greater your risk of developing breast cancer, research suggests. The Centers for Disease Control and Prevention recommends limiting alcoholic drinks to one per day. 
 
 Staying physically active has been associated with a reduced risk of several forms of cancer. Experts recommend exercising at least 150 minutes (2½ hours) per week. 
 
 Staying physically active has been associated with a reduced risk of several forms of cancer. Experts recommend exercising at least 150 minutes (2½ hours) per week. 
 
 The study was conducted in women younger than 55, and "breast cancer risk is low in women of these ages in general," Nichols said. 
 
 "So even though risk is highest five years after birth, that still translates to a very small increase in the absolute number of women who are being diagnosed with breast cancer," she said. 
 
 "If we took the women in our study and started following them around age 40, for example, and over the next 10 years by about age 50, we would have had about 2.2% of women develop breast cancer in the group that had had a recent child, and we would have had about 1.9% in the women who had not had any children," she said. "These are very small differences in the absolute measure, but they're still important because they are in the opposite direction of what we know about these risk factors in older women." 
 
 In general, pregnancy-related factors tied to a lower risk of developing breast cancer later in life include having your first full-term pregnancy at an early age, such as younger than 20; having more than one birth; having a history of preeclampsia; and breastfeeding over a longer period of time, according to the National Cancer Institute 
 
 Factors associated with a higher breast cancer risk include having your first full-term pregnancy at an older age, such as older than 30; having given birth recently, within about 10 years; and having taken diethylstilbestrol , a synthetic form of estrogen, during pregnancy. 
 
 Globally, breast cancer causes the greatest number of cancer-related deaths among women, according to the World Health Organization 
 
 This year alone, it is estimated that 627,000 women died from breast cancer worldwide, which is about 15% of all cancer deaths among women, according to WHO. In the United States, breast cancer is the most common cancer in women 
 
 About 41,000 women and 450 men die each year from breast cancer, according to the US Centers for Disease Control and Prevention 
 
 Relationship between childbirth and breast cancer risk 
 
 The new study included data on 889,944 women younger than 55. The data came from 15 international studies previously conducted in a research project called the Premenopausal Breast Cancer Collaborative Group 
 
 JUST WATCHED Breast cancer in young women Replay More Videos ... MUST WATCH Breast cancer in young women 00:59 
 
 None of the women had breast cancer when they were enrolled in the studies, which involved data from several European countries, the United States and Australia. 
 
 The data showed that, compared with women who had not given birth, women with children had an elevated breast cancer risk that peaked around five years after childbirth and continued for about 20 years -- regardless of whether women breastfed or not. 
 
 The researchers then noticed that this difference in risk among women who had had children and women who hadn't shifted about 23.6 years after childbirth. 
 
 "That's actually the point at which we started to not see much of a difference between the women who had a child and women who had not had children," Nichols said. "As you went further out from there, then the benefits of having children started to emerge." 
 
 The researchers also found that, even though breastfeeding did not appear to influence the findings, other factors did, including the age at which a woman first gave birth, how many children she had and whether she had a family history of breast cancer. 
 
 "One of the things that we want our study to be able to do is to contribute to new tools that will help predict breast cancer risk more effectively for young women -- so women who might be trying to decide with their providers when to start having mammogram screenings," Nichols said. 
 
 "In order to have a good tool to do that prediction, we need to know how risk factors operate in young women, and it's becoming increasingly clear that we can't take the information or the patterns we see in older women and apply them to younger women and assume they'll be the same," she said. 
 
 The study had some limitations, including that any breast cancer diagnoses during pregnancy in the data were not uniformly distinguishable from diagnoses made during early postpartum. 
 
 Also, the study was unable to explore the biological mechanisms behind why an association between breast cancer risk and childbirth even exists, but Nichols offered some ideas. 
 
 "What could be happening is that pregnancy is a time when there is rapid development of the breast tissue, and the cells in the breast are rapidly dividing, and we know that when tissue is expanding quickly that there's more potential for an error to occur within a cell or an error that's already there in the cell to have multiple copies made of it," Nichols said. 
 
 "So we don't think it's actually anything about pregnancy that's causing breast cancer. We think that it's possible that this rapid expansion of the breast tissue might make it easier for cancer cells to either grow or be started," she said, but more research is needed. 
 
 'This data should not be used to influence decisions about childbearing' 
 
 Though there is no clear explanation for this increase in breast cancer risk, young women should be aware of the small risk -- and that it can last for more than 20 years, especially if the woman is older during her first birth, has had several pregnancies or has a family history of breast cancer, said Dr. Francisco Esteva, medical oncologist at NYU Langone Health's Perlmutter Cancer Center in New York, who was not involved in the study. 
 
 "At the same time, screening mammograms are not generally recommended in women younger than 40 years of age," he said. "Therefore, if these results are confirmed, we would need novel approaches to identify breast cancer early in younger women, especially after childbirth." 
 
 Still, women also should know that the study findings should not influence their decision-making regarding having children, said Dr. Erica Mayer, a medical oncologist and clinical investigator in the Breast Oncology Center at the Dana-Farber Cancer Institute , who was not involved in the study. 
 
 "Deciding when to get pregnant, or whether or not to get pregnant, can be an intensely personal decision. This data should not be used to influence decisions about childbearing, as the cancer risks observed are overall fairly modest, as well as on a large population level, and it's difficult to extrapolate these risks to an individual person," Mayer said. 
 
 "However, evaluating personal cancer risk in a premenopausal woman is important," she said. "If a woman has a history that may influence risk -- such as a family history of breast cancer -- then she should discuss with her doctor the timing of initiation of mammographic screening, as well as whether referral to a genetic counselor would be helpful to evaluate for a genetic risk of breast cancer." 
 
 Overall, the study found what has been seen in previous research, Mayer said. 
 
 "It's known that pregnancy at a younger age may confer some long-term protective benefits against breast cancer, however it's also been recognized that in the immediate years following a pregnancy, there seems to be an increased risk of breast cancer that slowly resolves with time," she said. "The findings in this paper support and confirm the prior observations." 
 
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 "Nichols and colleagues' results add to a large body of evidence demonstrating a transient increase in breast cancer risk after childbirth. Given the consistency of this finding across studies, should women who have recently had a child make different decisions about breast cancer diagnosis, screening, or prevention? The answer, in general, is no," Armstrong wrote. 
 
 "Women with breast abnormalities should have a diagnostic evaluation regardless of time since childbirth," she wrote. "All women should pursue the healthy lifestyle behaviors, such as exercise and limiting alcohol intake, that reduce risk for breast cancer -- again, regardless of childbirth history."
– Just one alcoholic drink per day—even a teeny one—may not bode well for women on the breast cancer front, reports the Washington Post. That's the conclusion of a large-scale review by the American Institute for Cancer Research and the World Cancer Research fund that took a closer look at 119 studies involving more than 12 million women globally, and the impact of nutrition, diet, and physical activity on breast cancer risk. Although a typical alcoholic beverage contains 14 grams of alcohol, the report finds that even a small glass of wine, beer, or spirits (one with as little as 10 grams of alcohol) is tied to a 5% increased cancer risk in pre-menopausal women and 9% in post-menopausal women, indicating there may be "no level of alcohol use that is completely safe" when it comes to breast cancer, Ann McTiernan, one of the study's lead authors, tells the Post. Some good news: Researchers also found exercise plays a role in one's risk level—specifically, "vigorous" exercise on a regular basis cut the risk of breast cancer for both pre-menopausal women (a 17% reduction) and post-menopausal women (a 10% cut). So what if you like to throw one back but also often hit the gym? McTiernan notes alcohol increases estrogen levels, which has been tied to breast cancer risk, and that exercise can tamp those levels down—though that doesn't necessarily mean it will cancel out alcohol's effects. Although a healthy lifestyle doesn't offer complete assurance that cancer will stay away—McTiernan compares it to wearing a seatbelt, per the Post—the AICR estimates that a third of US breast cancer cases could be avoided if women kept to a healthy weight, exercised regularly, and didn't drink. (Alcohol has been tied to at least half a dozen types of cancer.)