Do MRI and mammography reliably identify candidates for breast conservation after neoadjuvant chemotherapy?

Neoadjuvant chemotherapy (NAC) may allow breast-conserving therapy (BCT) in patients who require mastectomy at presentation. Breast MRI is more accurate than mammography in assessing treatment response, but combined test reliability in identifying BCT candidates after NAC is not well described. We evaluated whether post-NAC breast MRI alone and with mammography accurately identifies BCT candidates.

In this retrospective study of 111 consecutive breast cancer patients receiving NAC, all had pre- and postchemotherapy MRI, followed by surgery. Posttreatment MRI and mammography results were correlated with surgical outcomes and pathologic response.

Fifty-one of 111 (46 %) patients presented with multicentric or inflammatory breast cancer and were not BCT candidates. The remaining 60 (54 %) were considered BCT candidates after downstaging (mean age: 47 years). All 60 had at least a partial response to NAC and were suitable for BCT on MRI after NAC. Forty-five of 60 (75 %) underwent lumpectomy; 15 of 60 (25 %) chose mastectomy. Forty-one of 45 (91 %) of lumpectomies were successful; 4 of 45 (9 %) required mastectomy. Twelve of 15 (80 %) patients choosing mastectomy could have undergone BCT based on pathology; 3 of 15 (20 %) did require mastectomy. Two of these three patients had extensive microcalcifications on mammogram, indicating the need for mastectomy despite MRI suitability for BCS. MRI alone correctly predicted BCS in 53 of 60 (88 %) patients. MRI plus mammography was correct in 55 of 60 (92 %), although only 9 of 45 (20 %) BCT patients and 4 of 15 (27 %) potentially conservable mastectomy patients had complete pathologic responses.

Posttreatment MRI plus mammography is an accurate method to determine whether BCT is possible after NAC is given to downstage disease.