Pre-op Breast MRI enables Personalised Treatment

The largest breast MRI study shows: Cases of more extensive surgery due to MRI are balanced by cases of less extensive surgery.

Author: mh/ktg
Session Topic: Mamma-MRI
Session Date: Wednesday, March 1st 2017
Presentation Code: SY Breast MRI "Current Challenges and New Trends"
Presentation Title: Preoperative Breast MRI: First results from the MIPA study
Name of Speaker: Francesco Sardanelli, University of Milan/Italy
Congress: ECR 2017, Vienna

Breast MRI helps to better estimate the disease extent; however, there is still uncertainty about whether it provides better outcome. When breast cancer is diagnosed, breast MRI helps to define the extend of disease, breast MRI is suitable for high-risk screening and as a problem solver in case of discordant results from X-ray and ultrasound. After neoadjuvant chemotherapy, breast MRI helps making the decision between breast-conserving surgery and mastectomy.

Francesco Sardanelli from Milan, Italy, reported on the latest results of the ongoing international MIPA study. MIPA – Multicenter International Prospective Meta-Analysis – focuses on the current use and value of preoperative breast MRI.

MIPA study – already more than 5200 patients included

The observational study includes women with newly diagnosed breast cancer receiving either preoperative MRI or conventional imaging. Surgical and clinical outcomes of both concurrent cohorts are compared. Primary endpoints are changes in the surgical plan, mastectomy rate, and reoperation rate. “Until today, more than 5,200 patients have been included in the study. Thereby, it is the largest study on breast MRI so far,” said Francesco Sardanelli.

Who decides about Breast MRI?

For non-preoperative purposes, 17.2 % of the patients had already undergone MRI prior to their study inclusion. When preoperative breast MRI was requested, this was a decision by the radiologist in 58.7% of the cases. In 31.7% it was the surgeon’s decision and in 40.4%, a surgeon was involved in making the decision.

Breast MRI Protocol

67% of breast MRI examinations were performed at 1.5 Tesla, 31% at 3 T, and 2% at 7T. In 84% of all cases, diffusion-weighted imaging (DWI) was part of the imaging protocol. When contrast-enhanced MRI was performed, 70% of the patients received gadobutrol at a dose of 0.1 mmol/kg body weight.

Inhomogeneous cohorts

Patients undergoing MRI were significantly younger (mean age 56±11 vs 60±11 years) and had denser breasts compared to the non-MRI group. They also showed significantly higher mastectomy rates (20.0 vs 15.4%).

MRI affects surgical plan (per-breast analysis)

In 73.0% of the cases of preoperative MRI, the surgical plan remained unchanged. The mastectomy rate increased from 20 to 21% when MRI was used. In 12.7% MRI led to a less extensive excision, whereas in 14.2% the excision was more extensive. “This is what we call personalized treatment,” said Sardanelli.

The reoperation rate for positive margins was significantly lower in the MRI-group (n=80; 8.3%) compared to the non-MRI group (n=135; 13.4%).

“These differences may not be interpreted as effects of the modality, they are mainly a result of the patient selection,” explained Sardanelli.

Conclusion

“In highly developed centers, about half of the patients with newly diagnosed breast cancer receive preoperative MRI”, said Sardanelli. “Our study draws an image of clinical reality.” Breast MRI is clearly used as a confirmation tool for mastectomy. Sardanelli underlined that in clinical practice mastectomy prompts MRI, not vice versa. In the MRI group, the number of more extensive breast cancer surgery based on MRI was compensated by less extensive surgery. The reoperation rate was significantly lower in the MRI-group.

“Radiologists and surgeons are the social drive for preoperative breast MRI,” concluded Sardanelli.

Public Discussion

Asked about the impact of higher breast density on the study, Sardanelli explained that the study provides lots of data on this topic; however, the authors will only gain deeper insights when 7,200 patients will be included. This might be reached within 2017, Sardanelli expected.

Regarding the importance of contrast-enhanced MR sequences for breast MRI in the future, Sardanelli expressed his personal view: “There is some evidence that diffusion imaging might be able to do it alone, but this is not the case for staging where contrast is needed.”