Supplemental MRI screenings of breast-cancer survivors are pricey and probably only worth the expense in subpopulations of women with certain clinical, biological and demographic characteristics. Further research is needed to define those parameters and, in the process, identify the women most likely to benefit.

So concluded a retrospective, single-institution review at Harvard-affiliated Brigham and Women’s Hospital in Boston, published online in Academic Radiology.

Diagnostic radiologist Catherine Giess, MD, and colleagues looked at 1,194 MRI exams in 691 patients, zeroing in on previously treated breast cancer patients for whom the oncologist or surgeon ordered screening MRI as supplemental surveillance.

Of those 1,194 exams, 1 percent turned up cancer versus 10.7 percent that brought back abnormal interpretations, with a positive predictive value for malignancy of 17.9 percent.

Patient age at the time of original cancer diagnosis ranged from 22 to 82 years (mean: 46.1 years), while age at the time of the MRI screening ranged from 26 to 86 years (mean: 52 years).

The authors cited previous studies supporting several of their conclusions, including that breast MRI has high sensitivity but only moderate specificity. Screening breast MRIs have not yet been shown to reduce cancer deaths in a randomized, controlled trial, they pointed out, although previous research has associated mammography with lowered mortality in a normal-risk population.

“[B]reast MRI is an expensive examination," wrote Giess and colleagues, "and false-positive results may lead to biopsy and/or follow-up imaging surveillance, leading to further healthcare costs.”

They noted that the cost-effectiveness of screening MRI in high-risk women has been discussed in the literature, with contradictory conclusions. Some research has shown that screening breast MRI is not cost-effective at a willingness-to-pay threshold of $50,000 per quality-adjusted life year—but other work has found that “the cost effectiveness of combined MRI and mammography for mutation carriers was finely balanced and quite dependent on the cost of the MRI examination.”

The authors said the limitations of their study included Brigham and Women’s status as a tertiary referral center whose patient population is likely to have a greater proportion of young breast cancer patients than a community practice.

“Other clinical reasons for referral for supplemental MRI screening remain unknown in this retrospective study but may include some … risk factors for recurrence and/or contralateral breast cancer or a patient’s desire for supplemental surveillance,” they wrote. “An analysis of possible reasons for supplemental screening breast MRI is beyond the scope of this retrospective review. Our patients are not linked to a tumor registry, and therefore, our reported sensitivity and specificity must be interpreted with caution.”