Could Half of All Breast Cancers Be Prevented?
NEW YORK (Reuters Health) – If girls and women of all ages adopted healthier lifestyle behaviors and the highest-risk women took preventive drugs like tamoxifen, the authors of a new report say fully half of breast cancers in the U.S. might be avoided.
“We really need to go back and work at breast cancer prevention starting at a young age,” Dr. Graham Colditz, associated director for prevention and control at Siteman Cancer Center and Washington University in St. Louis, a co-author of the report, told Reuters Health.
“Women need to have better access to understanding how breast cancer risk accumulates and how these lifestyle factors add up over the years to increase risk,” he said.
In addition to researching effective treatments and methods of catching cancers early, Colditz and his Washington University colleague Dr. Kari Bohlke argue that more emphasis should be on using what’s already known about what raises breast cancer risk.
For instance, just a small fraction of women who could benefit from the breast-cancer-preventing medications tamoxifen and raloxifene actually take them, the researchers note in their report in CA: A Cancer Journal for Clinicians.
Strategies for preventing breast cancer have received “far less attention” than efforts to improve treatment and early detection of the disease, Colditz and Bohlke write.
Nevertheless, they add, women can slash their breast cancer risk by avoiding alcohol or drinking very moderately; maintaining a healthy weight; being physically active; eating plenty of fruits, vegetables and whole grains; and, if they have children, breastfeeding them.
The risk associated with lifestyle factors begins to accumulate in early life, the researchers point out, and there is evidence that the time between a girl’s first period and her first pregnancy may be particularly important in determining breast cancer risk.
For example, research has found that teens who don’t drink alcohol at all may reduce their future risk of breast cancer by 20% to 30% compared to their peers who had at least one drink in the past 30 days.
And young adult women who drink less than one drink a day have a 20% to 30% lower risk than their peers who drink at least four drinks a week.
Young people who eat plenty of fruits, vegetables and whole grains are already reducing their future risk of several types of cancer – including breast cancer, according to the analysis.
Physical activity has the most breast-cancer-preventing benefit when women sustain it throughout their lifetimes, according to Dr. Colditz, but “it’s never too late to start,” he said.
Being obese after menopause is a key risk factor for breast cancer, he noted, but women who are able to lose weight in their post-menopausal years will bring down their risk of the disease.
“Those strategies are substantially reducing the onset of new cases and even deaths from breast cancer in postmenopausal women as well as premenopausal women,” he said.
Many women who could benefit from chemoprevention may shy away due to the complex risk-benefit profile associated with the drugs, Dr. Colditz noted. For example, tamoxifen increases the risk of endometrial cancer and blood clots.
“The field is pretty comfortable that those tradeoff issues are part of the reason we have substantially lower use in older women than one might expect given the magnitude of benefit that taking these preventive drugs actually conveys,” he said, noting that the medications will cut an individual woman’s risk of cancer in half.
One study found that the benefits of breast cancer chemoprevention outweigh the risks for nearly 8 million U.S. women in their 50s and 60s, he and Bohlke point out. But fewer than 120,000 women aged 35 to 79 in the U.S. are actually on tamoxifen or raloxifene.
“There’s a much larger proportion of women who could be talking to their doctors about chemopreventive strategies, but identifying them and giving them the tools to make the decision still seems to be one of the gaps in our strategy for implementing that whole process,” Colditz said.
CA: Cancer J Clinicians 2014.