also found that having an MRI before surgery did not
influence whether women would need additional surgery to remove more tissue. In each group, between 11 percent and 12 percent had to have more surgery.
After taking into account the initial surgery and second
operations, the researchers calculated that about 26 percent of those who had an MRI ended up having their entire breast removed, compared to 18 percent in the no-MRI group.
"It causes more mastectomies to start with, but it doesn't
decrease the number of women who started out wanting a lumpectomy and needing a mastectomy," said Morrow of the preoperative MRIs.
The study did not look at long-term outcomes, nor did it
examine the use of MRI to screen the opposite breast for signs that cancer had spread, while the results do not apply to certain subgroups of patients, including women with genetic mutations that predispose them to cancer.
"There may be select circumstances where we'd use it to
solve a problem, but for most women with breast cancer they don't need an MRI for their evaluation," Morrow said.