SAN ANTONIO – Preoperative MRI is effective for detecting mammographically occult, early-stage, hormone receptor (HR)-positive contralateral breast cancer (CBC) in older women, a study presented at the 2016 San Antonio Breast Cancer Symposium (SABCS) has shown.1

“Use of preoperative MRI staging in newly diagnosed breast cancer increases detection of synchronous CBC over other screening modalities,” said surgical pathologist Barbara Susnik, MD, PhD, Alina Laboratory, Hospital Pathology Associates, Minneapolis, MN. “However, it is associated with a high false positive rate, additional biopsies, extensive surgical procedures, and possibly increased psychological morbidity.

Therefore, researchers sought to investigate predictors of synchronous, mammographically occult but MRI-detected CBC in newly diagnosed women with breast cancer. For the study, researchers retrospectively analyzed data from 1894 women with breast cancer who had a preoperative breast MRI prior to undergoing surgical resection between 2010 and 2014.

They found that 201 patients had suspicious findings on contralateral breast MRI requiring biopsy and 60 had synchronous CBC, whether invasive carcinoma or ductal carcinoma in situ, detected on MRI.


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Results showed that the majority of CBC cases were stage 0 or IA (85%), HR-positive (98%), HER2-negative (89%), and low/intermediate grade (80%). In addition, women who were older (P < .001), had lobular versus ductal index cancer (P = .03), and had estrogen receptor (ER)-positive (P = .027) or progesterone receptor (PR)-positive (P = .002) tumors were more likely to have mammographically occult CBC.

“CBCs were diagnosed significantly more frequently in patients with index cancers that were HR-positive and HER2-negative compared to HER2-positive or triple negative invasive index cancers,” Dr Susnik added.

After adjusting for multiple variables, researchers found that ROC area, PR-positive status (P = .022), and older age (P = .004) were predictive of CBC. Each year of additional age increased the risk for developing CBC by 5% and patients with PR-positive tumors were 11 times more likely to have CBC than those with PR-negative cancers.

“Our results suggest that it may be possible to determine a subset of patients who are less likely to benefit from a preoperative breast MRI, an important implication in an era of increasing health care cost utilization awareness,” said Dr Susnik.

Reference

1. Susnik B, Lillemoe TJ, Swenson KK, et al. Predictive value of breast MRI in detecting mammographically occult contralateral breast cancer: Can we target women more likely to have contralateral breast cancer based on primary tumor clinicopathologic factors? Poster presented at: 2016 San Antonio Breast Cancer Symposium; December 6-10, 2016; San Antonio, TX.