What is MRI breast screening?
This is imaging of the breast using Magnetic Resonance Imaging (MRI) to pick up breast cancers in high risk women earlier than they would be found by either the woman or her doctor. MRI breast screening has been a welcome addition to the tools available to screen for breast cancer. However research has shown that the group of women who benefit most are those who are at a high lifetime risk of breast cancer. Women who undergo MRI breast screening, who are not at high risk of breast cancer, may be exposing themselves to the problems of over screening. Below we detail the benefits, downsides of MRI breast screening and the problems with over screening.
What are the benefits of MRI screening?
In numerous clinical trials in women at high risk of breast cancer, MRI breast screening has been found to pick up significantly more cancers than mammogram alone. In the most recent MRI Breast Screening trial in high risk women, 2150 participants were screened once a year with mammogram and MRI. During the period of the study, 35 breasts cancers were found in this group of women. None of these cancers were detected by mammogram alone, 23 were detected by MRI alone and 12 were detected by both mammogram and MRI.
What are the downsides of MRI screening?
Although MRI is good at picking up breast cancers, there is a significant chance it may also pick up other abnormalities that are not breast cancer. In most cases the abnormalities turn out not to be cancer, and would never have caused any problems to the woman’s health. This is a problem because to understand if the abnormality is cancer or not, the woman may require further scans, or even a procedure such a biopsy and in some cases, surgery. In the study previously described, there were 421 MRI scans that were abnormal leading to 182 biopsies but only 35 cancer diagnoses. The women who were not biopsied would have had either another form of imaging (such as ultrasound) or more frequent MRI scans.
What is wrong with having a MRI breast screen when you are not at high risk of breast cancer?
In general, this would be considered as over screening and is associated with the potential for harms or costs such as:
- Exposing women to unnecessary procedures: unfortunately sometimes MRI scanning leads to unnecessary biopsy or surgery of an area of the breast that turns out to be benign. Thus women are exposed to the discomfort and potential harms of the procedure without any benefits. When the risk of breast cancer for a woman is high and a biopsy is required it is more likely she is undergoing biopsy for a true cancer. On the other hand if the risk of breast cancer is low, it is more likely she is undergoing a biopsy for reasons unrelated to a true cancer.
- Psychological, time related and financial repercussions: it can be distressing for some women to undergo MRI scans particularly if they are found to have an abnormality that requires biopsy or further imaging. Additionally many women may have to take time off work, need to organise a baby sitter, pay for transport, parking or for additional procedures.
- Financial cost to the Australian Community – MRI is an expensive commodity and paying for unnecessary scans means there is less money available for other areas of the health care system.
Who can have a Medicare funded breast MRI?
In Australia women aged under 50 years who are defined as having a high lifetime risk for breast cancer are eligible for publically funded MRI Breast Screening paid for by Medicare Benefits Scheme (MBS). Unfortunately the current criteria are likely to exclude some high risk women who may benefit from having a breast MRI. This can include some women:
- who inherit their risk from their father’s side of the family may not qualify, as the criteria rely on having a certain number of close female relatives with breast cancer
- whose increased risk is caused by factors which are not familial, such as previous cancer treatment (i.e. chest radiotherapy for lymphoma)
On the other hand, some women who are eligible for screening, may not have a high risk when a comprehensive assessment by a Familial Cancer Centre is performed. These women are at risk of being over screened. Any doctor can order a breast MRI, however a Medicare rebate will only apply when it is ordered by a medical specialist e.g. breast surgeon.
How do I find out if I should be having a breast MRI?
Knowing your risk of developing breast cancer is the first step as this helps you and your doctor weigh the harms and benefits of this test. If you have a family history of breast or ovarian cancer, you can take the Know Your Risk tool which will help you start a conversation with your doctor. Your doctor can advise and refer you to a Family Cancer Clinic for a more detailed assessment if required. Once you Know Your Risk, your doctor and/or a breast specialist can advise you about what are the best tests to screen you for breast cancer based on your risk, personal health history and previous imaging results.