Patients’ decision to undergo contralateral mastectomy based on many factors

Newly diagnosed breast cancer patients who chose to undergo contralateral prophylactic mastectomy (CPM) did not make the decision based on MRI imaging Breast Imaging Reporting and Data System (BI-RADS) scores, but instead on a number of other patient factors, according to a study published in the October issue of Radiology.

Lead researcher Habib Rahbar, MD, of the University of Washington School of Medicine in Seattle, and colleagues found that out of 934 patients who had cancer in one breast, 86 (9.2 percent) chose to undergo CPM. These patients were a mean age of 48 and tended to be younger and to have a family history of breast cancer. They also were more likely to have ductal carcinoma in situ (DCIS).

“We found that MR imaging BI-RADS assessment (after exclusion of patients in whom MR imaging showed a cancer) did not have a significant association with CPM rates, whereas patient factors of younger age, greater breast density, family history, and index breast cancer pathologic results of DCIS showed a significant association with CPM rates,” commented Rahbar and colleagues.

The study was based on a retrospective review of the American College of Radiology Imaging Network 6667 trial. It looked at data on patients who did not have a known contralateral breast cancer at the time of surgical planning.

Although the rate of CPM in patients with unilateral breast malignancy has increased more than 11-fold from 1998 (0.4 percent) to 2007 (4.7 percent) the exact cause of this increase is debated, the authors wrote.

The use of breast MRI to determine the extent of the disease in patients with newly diagnosed breast cancer also has increased during this time frame. However, its effect on patient outcomes is less well understood.

Despite the increase in CPM, there is inadequate evidence that CPM improves survival, and the annual risk of developing a contralateral breast cancer is low (from 0.3 percent to one percent per year) and may be declining in the era of adjuvant hormonal therapy, the authors wrote.

Rahbar and colleagues noted that although the increased use of breast MRIs help identify otherwise occult cancer in the contralateral breast, some authors have questioned whether its increased use also has increased CPM rates.

“Although potential benefits of more accurate diagnosis of the extent of disease are acknowledged, there are concerns that false-positive breast MRI images may lead to more aggressive therapy than otherwise indicated,” the authors wrote.

The question of whether false-positive MR imaging findings in the contralateral breast of patients with newly diagnosed breast cancer cause more women to undergo CPM has substantial clinical ramifications, the authors wrote. However, the results of many studies have shown that the greatest increase in CPM rates has been observed among relatively younger; more highly educated white women of advanced socioeconomic status with a family history of breast cancer, they added.