Posts

5 July 2019

A study recently published in The Lancet Oncology found that the addition of MRI to mammography screening in high-risk patients detected breast cancers in earlier stages, but found that this technology was associated with a higher likelihood of false-positive results.

The study was performed at 12 hospitals in the Netherlands. Patients who were age 30-55 with a lifetime risk of breast cancer greater than 20% due to family history, but who tested negative for deleterious mutations in BRCA 1/2 and TP53 genes, were eligible to participate. Patients were randomized to one of the following surveillance arms:

  • Annual MRI, annual clinical breast exam, every other year mammogram [MRI-MG], or
  • Annual mammogram and annual clinical breast exam [MG]

1355 women were randomized and 231 were registered – the patients who were registered were those who did not provide consent for randomization, but followed one or the other protocol. Results from the patients who were registered but not randomized were used only in a portion of the data analysis.  

The authors found that over the 7-year study period:

  • 40 breast cancers were detected in the MRI-MG group, 15 were detected in the MG group
  • 24 invasive breast cancers were detected in the MRI-MG group, 8 were detected in the MG group
  • Invasive breast cancers detected in the MRI-MG group were smaller (9 versus 17 millimeters) than those in the MG group
  • Lymph node involvement was less likely to be seen in the MRI-MG group (4 of 24 cases, 17%) versus the MG group (5 of 8 cases, 63%)
  • There was one interval cancer (detected between screening exams) in the MRI-MG group and 2 in the MG group
  • Increased breast density was associated with higher stage at diagnosis in both study groups
  • Clinical breast exams generated a large number of false-positive results in both groups and detected only one cancer.

This study adds to the evidence nothing that the addition of MRI to screening mammography will increase the rate of cancer detection. National guidelines in the US do recommend breast MRI on an annual basis, in addition to annual mammography, for patients with a lifetime risk of 20% or greater. This study was not designed to assess outcomes for the patients who were diagnosed with breast cancer, but the authors postulated that MRI screening might lead to mortality reduction due to earlier stage at diagnosis. As reduction in mortality is the goal of screening, they stated that they plan to link the current study results with their national cancer database, and eventually publish 10-year mortality statistics for each of the groups. 

Additional Information: ASCO Post

18 September 2017

Breast MRIs are used in some newly diagnosed breast cancer patients, especially those with dense breast tissue. In addition, they are used as a supplement to mammography in women who are found to be at high risk. In order to distinguish between normal and cancerous tissue, an intravenous contrast dye is used. For MRI studies, the contrast material that is used is gadolinium-based.

Gadolinium is a heavy metal, and it has the potential to be retained in the brain and kidneys. Some recent studies in both the scientific and lay press have focused on the safety of gadolinium. While there have only been scattered reports of adverse events, an FDA advisory panel voted for warning labels and for more study.

The FDA advisory focuses primarily on a class of agents known as “linear”. The “macrocyclic” gadolinium contrast agents do not appear to have the same risk of depositing in the brain or kidneys. Both types of gadolinium contrast can be used for breast MRI studies. If you have concerns, ask the facility which form of gadolinium they use.

*Note – UCLA facilities (Westwood, Santa Monica and Santa Clarita), San Fernando Interventional Radiology (a RadNet facility) and Providence St. Joseph Hospital all use gadavist, a “macrocyclic” form of  gadolinium contrast, for their breast MRI studies. Because facility practice patterns may change over time, ask at the time of your exam if you have concerns.

24 September 2015

It is not uncommon that after a breast cancer diagnosis, a breast MRI is recommended. We know that there are limitations to mammography – it might not show everything of concern, especially in women with dense breast tissue. The idea behind preoperative MRI is that if there are other lesions, better to know about them and determine if they are cancerous or not, before going to surgery. This should lead to better surgical outcomes. Makes sense.

The problem is, studies have not been able to show a benefit to preoperative MRI. This was addressed in a recent issue of JAMA Oncology. Dr. Angel Arnaout and colleagues reported on the Use of Preoperative Magnetic Resonance Imaging for Breast Cancer: A Canadian Population-Based Study. In this retrospective population-based study, 53,015 patients with operable (early-stage) breast cancer were identified between 2003-2012.

Overall, close to 15% of patients underwent an MRI, and the use increased from 3% to 24% during the 10 year period.

Screen Shot 2015-10-15 at 2.08.59 PM

Patients undergoing a preoperative MRI were more likely to be younger, of higher socioeconomic status, cared for in teaching hospitals, being cared for surgeons with a high volume of breast cancer cases, and cared for by younger surgeons. Preoperative MRI was associated with a higher likelihood of additional imaging and biopsies, greater than 30 day wait time to surgery, and higher rates of mastectomy as well as contralateral prophylactic mastectomy.

These findings were discussed by Drs. Habib Rahbar and Constance Lehman in an accompanying editorial. They pointed out several limitations in the study, such as not knowing the MRI results, and not having the genetic mutations status (such as BRCA 1/2) of the patients. However, they noted that “this study adds to the growing body of evidence that the use of MRI in the preoperative setting is associated with more aggressive surgery of the affected breast”. They also noted that given concerns of breast cancer overtreatment, we need to modify our approach. They pointed out that MRI might be useful in developing individualized treatment approaches, such as multiple lumpectomies if more than one cancer is found (instead of mastectomy). They appropriately called for more research to determine how preoperative breast MRI should best be utilized.