Mammography Not Always Enough
July 26, 2001 -- Women with a strong family history of breast cancer need frequent, careful monitoring to stay on top of early signs of the disease. Mammography has traditionally played a large role in this process, but it may be taking a backseat to newer, better technology.
A new study in the July 18 issue of Journal of the National Cancer Institute suggests an imaging technology called MRI, or magnetic resonance imaging, may better detect cancers on yearly breast exams than traditional mammography. MRI is not routinely used to screen for breast cancer, but several large studies, including one ongoing at the University of Pennsylvania, are researching its use for this purpose.
In the newest study, mammography and MRI were compared in a group of women with a strong family history of breast cancer. The majority of the 179 women were under age 50.
According to study author Mark J. Stoutjesdijk, MD, MRI detected 13 cancers, seven of which had not been seen on mammography. This may be because breast tissue is thicker in younger women, making mammography less able to detect tiny changes. MRI, on the other hand, can better penetrate the tissue to find tiny abnormalities, many of which are in the very early stages. MRI also can clarify a questionable mammogram.
One advantage MRI has over mammography is that MRI creates a three-dimensional image of the breast without using radiation. Although the amount of radiation women are exposed to during mammography is small, some experts are concerned that women at high risk of breast cancer may be at high risk of genetic damage induced by even small doses of radiation -- therefore, possibly increasing their risk of breast cancer a little more.
Stoutjesdijk, of the University Medical Center St. Radboud in Nijmegen, the Netherlands, says if MRI is better than mammography at detecting early changes, it could have important implications for women with a family history of early, aggressive, breast cancer. These women might otherwise choose to have their breasts removed -- a procedure known as prophylactic mastectomy -- rather than take the chance of cancer being missed on mammography.
But Stephen B. Edge, MD, says while MRI looks promising for detecting breast cancer, this study does not prove that MRI is better or that mammography cannot detect early cancers.
"MRI is a very exciting technology and may well prove to have a real role in screening women who are at very high risk by virtue of [genetic] susceptibility," says Edge, a breast cancer surgeon at Roswell Park Cancer Institute in Buffalo, N.Y. "But we find that many times people come to us, and they have not had a good mammogram. And when you then do a good mammogram you find [the cancer]."
Another expert also urges caution regarding MRI.
"I think probably MRI is going to have a role in screening some high-risk women, but I don't think you can just across the board say that because you are at high risk you should have an MRI," says Katherine Evers, MD, a radiologist at Fox Chase Cancer Center in Philadelphia.
Despite its advantages, MRI is more expensive and more time-consuming than mammography, and it is problematic for claustrophobic people who don't have access to the newer open MRI.
Large trials comparing MRI with mammography are underway in both the U.K. and the Netherlands, according to the study authors. These will help answer the question of what to do.