Using a database to predict breast cancer risk gains credibility
(HealthDay News) Probability. Risk factor. Genetic tendencies. Lifestyle variants.
These terms have become as much a part of diagnosis and prognosis for major disease as a biopsy is for cancer.
And now, the use of a database in the predictability of breast cancer has begun to prove its worth. "Breast cancer is multifactorial. It would be rare for there to be a single environmental chemical that alone would be sufficient to cause an increase in breast cancer," said Dr. Robert Schneider, co-director of breast cancer research at New York University School of Medicine in New York City.
"In many cases, an increased risk of breast cancer is quite small, and we don't yet know how each factor affects the risk of breast cancer," he said, explaining that it's similar to a puzzle. "We need to know how all of the pieces fit together, and this database begins to help us start assessing some of that." The database, a joint project of Susan G. Komen for the Cure and the Environmental Factors and Breast Cancer Science Review project led by the Silent Spring Institute, includes information on 216 chemicals, diet, smoking, physical activity and weight that may play a role in the development of breast cancer.
Fewer than 100 chemical compounds have been identified as human carcinogens by the International Agency of Research on Cancer. However, that doesn't mean that all other chemicals are safe, just that they haven't been tested. And, an estimated 80,000 chemicals have been registered for commercial use in the United States , according to the database study, which was published in a recent issue of the journal Cancer .
Although many factors have been associated with breast cancer, Schneider said his top three would include the chemical bisphenol A, radiation exposure from CT scans and delayed first pregnancy.
Bisphenol A (BPA) is an estrogenic chemical found in many products made of polycarbonate plastic (clear, hard plastic), such as baby bottles, reusable water bottles, food storage containers, food cans and water supply pipes, according to the National Institute of Environmental Health Sciences. Although no human studies have confirmed an association with breast cancer, a study done in mice suggests there may be a link. However, the U.S Food and Drug Administration recently said the agency felt there were "adequate margins of safety" for the chemical in the amounts commonly consumed.
"We don't know what constitutes an unacceptable level," said Schneider who would prefer to err on the side of caution and limit BPA exposure, especially in infants and young girls. Schneider said another concerning risk factor is the amount of radiation people are exposed to for routine health problems, particularly from CT scans.
Although the last risk factor from Schneider's top three -- delayed first pregnancy -- isn't one people are likely to change, he said it's important to be aware of it. "In a modern society, it's exceedingly difficult to have a pregnancy before 20 when it would be quite protective," said Schneider.
Dr. Jay Brooks is chair of hematology/oncology at Ochsner Health System in Baton Rouge , La. He said, "When you look at environmental and chemical risk factors, you have to remember that we live in a sea of chemicals, and those chemicals have made our lives so much nicer, and it's hard to know exactly what each one does to an individual's risk.
"I advise my patients to try to control the things you have good control over. Weight is a huge issue in breast cancer, as is the use of combined estrogen/progesterone after menopause," he added.
Brooks said extra weight is a risk factor that many women underestimate, but being overweight clearly increases risk. And, he said, estrogen therapy alone used to ease menopausal symptoms doesn't seem to increase risk the way the estrogen/progesterone combination does.
On the Web
To learn more about breast cancer risk factors, check the searchable database from the Silent Spring Institute.
Robert Schneider, Ph.D., co-director, cancer research, New York University School of Medicine, New York City; Jay Brooks, M.D., chair, hematology/oncology, Ochsner Health System, Baton Rouge, La.; June 15, 2007, Cancer
Publication date: January 2009
Serena Gordon, HealthDay Reporter
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