Breast cancer risk related to changes in breast density as women age
Automated breast density measurement is predictive of breast cancer risk in younger women, and that risk may be related to the rate at which breast density changes in some women as they age, according to research being presented today at the annual meeting of the Radiological Society of North America (RSNA).
Breast density, as determined by mammography, is already known to be a strong and independent risk factor for breast cancer. The American Cancer Society (ACS) considers women with extremely dense breasts to be at moderately increased risk of cancer and recommends they talk with their doctors about adding magnetic resonance imaging (MRI) screening to their yearly mammograms.
“Women under age 50 are most at risk from density-associated breast cancer, and breast cancer in younger women is frequently of a more aggressive type, with larger tumors and a higher risk of recurrence,” said the study’s senior author, Nicholas Perry, M.B.B.S., FRCS, FRCR, director at the London Breast Institute in London, U.K.
For the new study, Dr. Perry and colleagues compared breast density and cancer risk between younger and older women and analyzed how the risk relates to changes in breast density over time. The study group included 282 breast cancer cases and 317 healthy control participants who underwent full-field digital mammography, with breast density measured separately using an automated volumetric system.
“In general, we refer to breast density as being determined by mammographic appearance, and that has, by and large, in the past been done by visual estimation by the radiologist - in other words, subjective and qualitative,” Dr. Perry said. “The automated system we used in the study is an algorithm that can be automatically and easily applied to a digital mammogram, which allows an objective and, therefore, quantitative density measurement that is reproducible.”
Breast cancer patients showed higher mammographic density than healthy participants up to the age of 50. The healthy controls demonstrated a significant decline in density with age following a linear pattern, while there was considerably more variability in density regression among the breast cancer patients.
Breast Cancer Risk Factors
Every woman wants to know what she can do to lower her risk of breast cancer. Some of the factors associated with breast cancer - being a woman, your age, and your genetics, for example - can’t be changed. Other factors - being overweight, lack of exercise, smoking cigarettes, and eating unhealthy food - can be changed by making choices. By choosing the healthiest lifestyle options possible, you can empower yourself and make sure your breast cancer risk is as low as possible.
The known risk factors for breast cancer are listed below. Click on each link to learn more about the risk factor and ways you can minimize it in your own life. If a factor can’t be changed (such as your genetics), you can learn about protective steps you can take that can help keep your risk as low as possible.
Established risks:
Being a Woman
Just being a woman is the biggest risk factor for developing breast cancer. There are about 190,000 new cases of invasive breast cancer and 60,000 cases of non-invasive breast cancer this year in American women.
Age
As with many other diseases, your risk of breast cancer goes up as you get older. About two out of three invasive breast cancers are found in women 55 or older.
Family History
Women with close relatives who’ve been diagnosed with breast cancer have a higher risk of developing the disease. If you’ve had one first-degree female relative (sister, mother, daughter) diagnosed with breast cancer, your risk is doubled.
Genetics
About 5% to 10% of breast cancers are thought to be hereditary, caused by abnormal genes passed from parent to child.
“The results are interesting, because there would appear to be some form of different biological density mechanism for normal breasts compared to breasts with cancer, and this appears to be most obvious for younger women,” Dr. Perry said. “This is not likely to diminish the current ACS guidelines in any way, but it might add a new facet regarding the possibility of an early mammogram to establish an obvious risk factor, which may then lead to enhanced screening for those women with the densest breasts.”
For instance, some women might undergo a modified exposure exam at age 35 to establish breast density levels, Dr. Perry noted. Those with denser breast tissue could then be followed more closely with mammography and additional imaging like MRI or ultrasound for earlier cancer detection and treatment.
“It has been estimated that about 40 percent of life years lost to breast cancer are from women under 50 diagnosed outside of screening programs,” Dr. Perry said. “In my practice, which is largely composed of urban professional women, 40 percent of cancers year to year are diagnosed in women under 50, and 10 percent in women younger than 40.”
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Co-authors are Katja Pinker-Domenig, M.D., Kefah Mokbel, M.B.B.S., FRCS, Sue E. Milner, B.Sc., and Stephen W. Duffy, M.Sc.
Note: Copies of RSNA 2013 news releases and electronic images will be available online at RSNA.org/press13 beginning Monday, Dec. 2.
RSNA is an association of more than 53,000 radiologists, radiation oncologists, medical physicists and related scientists, promoting excellence in patient care and health care delivery through education, research and technologic innovation. The Society is based in Oak Brook, Ill.
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Linda Brooks
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Radiological Society of North America