Mastectomies prompt MRI

Concerns that preoperative breast MRI leads to unnecessary mastectomies are still common. Sardanelli presented results from the MIPA trial showing that scheduled mastectomy prompts MRI, not vice versa.

Preoperative breast MRI is a controversial modality. Francesco Sardanelli (University of Milan, Italy) pointed out that it is already common practice to perform breast MRI without surgery, for example for high-risk screening and guiding the therapy decision after neoadjuvant chemotherapy (NAC). However, currently the acceptance of preoperative breast MRI by clinicians is often low, Sardanelli added. One common reason is the fear of overdiagnosis, leading to overtreatment, i.e. unnecessary mastectomies.

Limitations of current studies

According to Sardanelli most studies report on women who underwent preoperative MRI, but do not consider what happened to women with breast cancer who did not undergo preoperative MRI. In addition, and perhaps even more important, is the fact that the therapy planning before the preoperative MRI is not known. “So it is unclear if the mastectomy was already planned before the MRI or a direct consequence of the MRI”, Sardanelli explained.

The MIPA study

The MIPA study is an ongoing prospective observational multicenter study with two concurrent cohorts. Over 6,000 patients with newly diagnosed first breast cancer that were not candidate to NAC were enrolled. Patients either underwent MRI before surgery (MRI group) or did not (no-MRI group).

Sardanelli presented data from 2,425 patients, 1,201 (49.5%) with MRI and 1,224 (50.5%) without. While the majority of preoperative MRIs were requested by radiologists alone, surgeons were involved in 40% of all request, either alone (32%) or together with a radiologist (8%). “In 40% the surgeon actually wants a preoperative MRI to be conducted”, Sardanelli concluded.

Mastectomy prompts MRI, not vice versa

There was a significant difference in the mastectomy rate planned at mammography/ultrasound between the groups: 15.4% for the no-MRI group and 20.0% in the MRI group. “This is a selection bias that needs to be considered in the interpretation of all studies”, Sardanelli pointed out. The increase in mastectomies as a result of a preoperative MRI was low (1.1%). “Mastectomy prompts MRI, not vice versa”, Sardanelli emphasized.

Additional results from the MIPA trial showed that around 14% of the patients in the MRI group received more extensive breast conservation surgery (BCS), while nearly 13% received less extensive BCS. “This is nothing else than personalized medicine”, noted Sardanelli. Further, reoperation rates were lower in the MRI group (8.3%) compared to the no-MRI group (13.4%).

Conclusion

Contrary to common fears, first results from the MIPA trial indicate that preoperative breast MRI does not increase the rate of mastectomies. What is more, preoperative breast MRI enables personalized breast cancer treatment. Sardanelli expects that these results will help increase the acceptance of preoperative MRI.