Phil Evans, M.D. Answers Questions On: Mammography

For women at average risk, I am a strong proponent of starting annual breast cancer screening with mammography at age 40 and continuing annually as long as the individual is healthy. While some organizations have recently changed their recommendation to screening every other year, we know that some malignancies can grow quite quickly during that timeframe. Many studies confirm that the earlier you find breast cancer, the better, and that 70 percent fewer deaths occur when we screen annually rather than every other year.

Mammography is not perfect; it doesn’t find all cancers. A small percentage of breast cancer infiltrates the tissue and doesn't cause detectable changes in the mammogram. Or cancers may not show up on the film because they are in a location not included on well seen on the mammogram. To screen patients at the highest risk for breast cancer, we use MRI, and for those at intermediate risk, we offer tomosynthesis (3-D mammography) and ultrasound.

One of the big misconceptions about breast cancer is that only women who have a family history or genetic mutation need regular mammograms. But about 75-80 percent of breast cancers occur in women with no family history of the disease.

There are several models that can be used to calculate a woman’s risk for breast cancer, based on family or personal medical history, number of biopsies, number of pregnancies, age at onset of menstruation, age at menopause, and so on.

People who have a strong family history of breast cancer are assessed by a geneticist in our high-risk program to determine their exact risk and, in consultation with a breast surgeon and a breast imaging radiologist, how often they should be screened and by what method.

Roughly half of all women have dense breast tissue and 10 percent have extremely dense tissue. As the density of breast tissue goes up, sensitivity of mammography goes down. So women who have dense tissue may need other types of screening in addition to mammography, such as ultrasound or MRI, depending on their risk factors.

Research has shown that when we use both mammography and an additional test, we find more malignancies. And with contrast-enhanced MRI (magnetic resonance imaging), which can reveal the abnormal blood vessels of tumors, we find the greatest number of breast cancers. So for women at very high risk, our recommended protocol is annual mammography and MRI, alternating between them every six months.

For women who are not comfortable with an MRI, we offer a technology called PEM (positron emission mammography) that evaluates tumor physiology. We have also found ways to make MRI screening easier on patients by reducing the duration of the procedure and placing patients in the scanner so that it feels less claustrophobic.

In the coming years we will be looking at new methods to image women in a very personalized way.

For instance, a woman with dense breasts and no other risk factors may be best served having yearly 3-D mammography while someone at higher risk may get alternating mammography plus MRI yearly, and women at average risk without dense breasts receive a standard digital mammogram.

There are also ongoing studies of new screening technologies such molecular breast imaging and FAST breast MRI. So, selecting and personalizing all of these techniques for the women who need them is going to be our challenge in the future.