Dense Breasts and Breast Cancer Risk
Having dense breasts can increase a woman's risk of cancer and make breast cancer harder to spot on mammograms. Here's what you need to know.
Medically reviewed by Niya Jones, MD, MPH
With her small breasts and healthy habits like eating well and exercising, 50-year-old Betsy Tecco of Collegeville, Pa., was surprised in 2009 when she found a lump that turned out to bebreast cancer. Even more shocking, however, was her doctor’s belief that the cancer had started growing 8 to 10 years earlier.
“In all that time I had annual mammograms and manual exams with no suspicious findings,” recalls Tecco. Even after discovering the lump, a mammogram showed nothing — it took an ultrasound, MRI, and needle biopsy to ultimately make the breast cancer diagnosis. Tecco has dense breasts, which can make mammogram detection of breast cancer much more challenging.
What Are Dense Breasts?
Breasts consist of several types of tissue including skin, fat, glandular tissue, and blood vessels. Dense breasts have more glandular (milk-producing) tissue than fatty tissue. “On mammograms, dense breasts appear white, which can easily hide a cancer, which also appears white,” explains Louise O’Shaughnessy, MD, medical director of breast imaging at Imaging Healthcare Specialists in San Diego. “In contrast, fatty tissues appear dark on a mammogram, making it easier to spot a white cancer.”
Breast density varies from woman to woman and can also change as women age. For example, findings at the 10th Annual Meeting of the American Society of Breast Surgeons in 2009 revealed that nearly 75 percent of women in their forties had dense breasts, but this number decreased to 54 percent of women in their fifties. Only 42 percent of women in their sixties had dense breasts, and by the time they got to their seventies, the proportion was just shy of 31 percent.
Detecting Your Breast Density
Breast density is not something a woman or her doctor can guess by look or feel. Nor can it be estimated based on family history or age — just because breast density generally decreases as a woman ages doesn’t mean this is true for everyone.
“The only way a woman can know if she has dense breasts is if she asks her doctor or the radiologist who performs her mammogram,” says Rachel F. Brem, MD, director of breast imaging and intervention and vice chair of the department of radiology at George Washington University Medical Center in Washington, D.C. The doctor who ordered the mammogram should receive a formal report, which notes whether or not you have dense breasts.
Dense Breasts and Cancer Risk
Dense breasts can increase a woman’s cancer risk in two ways. First, as described above, the white appearance of dense breast tissue can camouflage breast cancer, making it harder to detect. Independent of this visual challenge, however, breast density in and of itself has also been found to be a risk factor for breast cancer. A large study published in the Journal of the American Cancer Institute, which reviewed mammograms from nearly 3000 postmenopausal women with and without breast cancer, found that women with more dense breasts had nearly four times the risk of developing cancer than those with less dense breasts.
But although detecting breast cancer in women with dense breasts can be more complicated, mammogram screening is still the recommended method for those with an average risk of cancer. “In other words, women without a strong family history of breast and/or ovarian cancer or one of the known genetic mutations associated with breast cancer should only be screened with mammography,” says Hal Kipfer, MD, assistant professor of clinical radiology at the Indiana University School of Medicine and section chief of breast imaging at Indiana Radiology Partners in Indianapolis, Ind. For those at higher risk, other options include breast ultrasound or an MRI in addition to a mammogram.
Ultimately, whether a woman has dense breasts or not, mammograms play an important role in cancer detection and in staying healthy.
Last Updated: 07/28/2011
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