U.K. study strengthens case in support of breast MR screening

A U.K. multicenter study has shown that a combination of MRI and mammography offers the best way of detecting breast cancer in women with a high genetic risk of the disease. The results add more weight to arguments for routine breast MRI for women carrying BRCA mutations and possibly for omitting mammography altogether.

The need for both exams may diminish as practitioners gain experience in spotting early-stage cancers, said Dr. Ellen Warner, a medical oncologist at Toronto-Sunnybrook Regional Cancer Centre, where a similar MRI-mammography protocol has been trialed.

"I think it is a function of time and experience," Warner said. "If a particular center reviews its data over three or four years and finds that virtually every cancer was found on MRI and that nothing was missed that showed up on x-ray mammography, then they could probably say: 'We can drop mammography now for these high-risk women.'"

The U.K. report, published online May 16 by The Lancet, involves a study of 649 women aged 35 to 49 with a high familial risk of breast cancer. All were offered annual x-ray mammography and contrast-enhanced MRI over a two to seven-year period.

The investigators found MRI significantly more sensitive than mammography in detecting breast cancers across the group (77% versus 40%), and combining the results increased the sensitivity to 94%. MRI proved especially effective in BRCA1 mutation carriers, detecting all tumors. Both techniques were needed to spot all cancers in the women carrying BRCA2 mutations.

"It may be that one day we can say, 'MRI can give us all the answers.' But I would be very hesitant to say that at the moment," said Dr. Martin Leach, who chaired the advisory group. "Of course, we are at the beginning of a new approach, and as we all learn, there is no doubt that the results will get better."

The study, which involved 22 U.K. centers, proves that combining MRI and mammography is a robust and practical approach to surveillance screening in this high-risk population, Leach said. Previously published comparative studies used data from no more than six sites.

In a commentary accompanying the study, Warner said it's not known whether surveillance MRI reduces mortality. She also noted that conducting a randomized comparison of surveillance mammography with or without MRI is no longer feasible.

"Until survival data are available by indirect means, physicians must decide whether the potential benefit of MRI surveillance justifies its much higher cost per screening study (about 10 times that of mammography) and lower specificity, resulting in increased patient morbidity and additional costs," she wrote.