Do Not Base Pre-Operative MRI Recommendations on Patient or Tumor Traits

The debate around who should undergo pre-operative MRI continues to grow in complexity. It is still not possible to pinpoint which women should undergo the scan, according to new research, so excluding some women could lead to negative outcomes.

Despite a large patient population of more than 1,000 women who underwent pre-operative MRI, a recently conducted retrospective study determined no characteristics specific to patients or tumors could be used to predict pre-operative MRI outcomes. Results of the study, led by Habib Rahbar, M.D., clinical director of the Seattle Cancer Care Alliance at the University of Washington, were published in Radiology: Imaging Cancer.

Pre-operative MRI is already recommended for patients with dense breast tissue, invasive lobular carcinoma, or suspicious mammogram results. This study, however, did not find any traits linked to additional cancers. Consequently, they cautioned that only using this type of scan with some patients could leave some cancer undetected.

An example of a true-positive preoperative MRI outcome. Preoperative breast MRI was performed in a 48-year-old woman with newly diagnosed left breast cancer in the upper inner quadrant (invasive ductal carcinoma [white arrow]) measuring 29 mm in size. (a) Subtracted maximum intensity projection and (b, c) postcontrast T1-weighted series demonstrate a second irregular-shaped mass (arrowhead) in the lower outer quadrant measuring 7 mm and regional heterogeneous nonmass enhancement (black arrow) involving predominantly the upper inner and upper outer quadrants. MRI-guided biopsy of the mass revealed pleomorphic lobular carcinoma. The nonmass enhancement was not biopsied since this established multicentric disease. Mastectomy performed after neoadjuvant chemotherapy demonstrated no evidence of residual disease (pathologic complete response). Courtesy: Radiology: Imaging Cancer; RSNA

“If these factors are used to exclude older women, women with non-dense breast tissue, and women with specific molecular subtypes from undergoing pre-operative MRI, these women may not be benefiting from a test that could detect additional disease prior to surgery,” wrote Rahbar’s team.

Related Content: Pre-Operative Breast MRI Diagnoses More Cancers in Women with DCIS

To determine whether it was possible to pinpoint which patients might benefit most from pre-operative MRI, Rahbar and his colleagues culled data from a large cancer center in Washington that had conducted pre-operative MRI on 90 percent of breast cancer patients under age 70 since 2005. The team analyzed patients for several factors that are associated with malignant tumors, including age and breast density.

Overall, the study population included 1,396 women who received pre-operative MRI between 2005 and 2015. Of the group, 419 underwent at least one additional biopsy as a result of their MRI findings, and 181 received a new malignancy diagnosis. Ultimately, however, Rahbar said, the data analysis revealed no patient or tumor factors that were significantly associated with the biopsy-confirmed malignancies picked up by pre-operative MRI.

Even though these findings confirm the utility of pre-operative MRI in finding additional cancers, they do not reveal any particular type of patient who would benefit from the scans most. Therefore, he and his colleagues concluded, the use of pre-operative MRI should not be limited to patients with only a sub-set of characteristics.

The team did unearth three other significant relationship, though.

• Patients under age 50 were more likely to have a biopsy than older women (35 percent to 28 percent, respectively), as well as to receive negative biopsy results (19 percent to 14 percent, respectively).
• Women with dense breasts were more likely than those without it to have a biopsy (32 percent to 26 percent, respectively) and to receive negative biopsy results (19 percent to 14 percent).
• Women with HER2-negative cancer were more apt than those with HER2-negative to undergo a biopsy (31 percent to 23 percent, respectively), but they were less likely to receive positive biopsy results (82 percent to 89 percent, respectively).

Ultimately, the team said, regardless of any patient selection bias or potential over-estimation of false biopsy results, their results do not support looking for or relying on any patient- or tumor-specific characteristics for recommendations of pre-operative MRI.

“This study highlights the lack of evidence driving current pre-operative MRI expert recommendations and suggest that larger, similar analyses should be performed to help better guide pre-operative MRI societal recommendations and practice guidelines,” they said.