Breast Cancer Screening: Breast Imaging MRI vs Mammogram Exam
What is the difference between breast cancer imaging MRI versus mammogram? Multiple healthcare guidelines recommend starting to screening women for breast cancer starting age of 40. This recommendation is due to the fact that on average, 1 in 8 women will be diagnosed with breast cancer in her lifetime.
Traditionally, mammograms have been used for screening, however, this technology is over 100 years old. While improvements have been made with mammogram imaging, in essence, it is similar to the sensitivity of x-rays and screenings through mammographies can miss the majority of breast cancers in young women.
In fact, the sensitivity of traditional mammograms in a young woman with dense breasts (generally meaning a woman between the ages of 40 through her early 50s), have been shown to be at best 50%, with upwards to two-thirds successful of identifying breast cancer lesions due to the inability to decipher normal breast architecture and which substances are cancers. The implication is that we're better off flipping a coin to determine if a woman in her 40s has breast cancer as opposed to doing a traditional 2-dimensional mammogram screening. In addition, if a woman does have a 2-dimensional mammogram done which reports a negative result; with such poor ability to detect early breast cancer, she will wrongfully walk away with a full sense of security.
Several studies have demonstrated that screening for breast cancer with MRI screens of the breast significantly improve our sensitivity of being able to detect early lesions with sensitivity of the screenings being in the high 90s percentile, upwards of 98 percent.
It is imperative that the imaging is done with high quality MRI equipment and the result is being reviewed by a fellowship-trained breast-radiologist. Another reason for the high success rate is even though MRIs of the breasts are able to better identify early breast cancers, they can also pick up a number of non-specific spots which are often false alarms, also called "false positives." The ability to navigate through those complex charts requires an appropriate level expertise from a radiologist.
The reason why MRIs are more sensitive in picking up early breast lesions in young women is because the breast architecture is much more dense in a woman with high levels of estrogen and progesterone. As such, these hormones contribute to breast diagrams looking much more opaque on the standard mammogram image which can easily miss a significant amount of early breast cancers, as high as 70%.
While 3-D, tomosynthesis mammograms have been introduced to improve our traditional 2-dimensional mammogram technology, this improvement pales in comparison to a breast MRI. In fact, breast cancer guidelines recommend starting off with the woman's lifetime risk of breast cancer assessment prior to ordering a specific imaging modality.
Women who have a high risk of breast cancer, defined as greater than a 20% likelihood in a woman's lifetime, have a greater likelihood of approval for breast MRI as a screening modality–because they are at high-risk, and there is a greater likelihood that a mammogram will not identify a lesion.
Unfortunately, the difference of not being able to identify a cancer is often not just limited to early breast cancer, and often has to do with cancer's pattern of growth spread. For instance, some breast cancers don't grow as big as a ball or orange but more like a sheet of Swiss cheese, such that they don't form a discrete large lesion but rather more like a sheet through the breast. Invasive lobular carcinoma, which constitutes about 20% of breast cancer, often does this and is frequently missed with mammograms, especially in younger women.
Conclusively, it is imperative that as an oncologist, I'll not only need to pick the right imaging modality for a woman, but also need to conduct a genetic analysis (based on family and personal history of cancers), an endocrine (based on hormone exposure, birth control pregnancies, breast-feeding height, age of the 1st period onset as well as menopause), lifestyle exposure (based on exposure to carcinogens, radiations, smoking, alcohol, mobility and exercise, annual based products), as well as plethora of different medical conditions which put a woman at high risk for breast cancer, such as diabetes, cardiovascular disease and autoimmune disease -- these risks factors all contribute to determining a woman's likelihood of developing breast cancer in her lifetime.
If you have further questions, please contact our office to see how we can help you and your family.