The clinicopathological and MRI features of patients with BRCA1/2 mutations in familial breast cancer.

Background: To determine the histopathological and MRI features of BRCA1/2 mutation-associated familial breast cancers compared with those of BRCA1/2 mutation-negative and sporadic breast cancers and to further compare the imaging features of cancers from BRCA1 and BRCA2 mutation carriers according to lesion type on MRI.

Methods: A retrospective review of medical records was conducted to determine tumour clinicopathologic features and MRI characteristics between June 2011 and July 2017, and 93 lesions with BRCA mutations, 93 lesions without BRCA mutations from familial breast cancers and 93 lesions from sporadic breast cancers were included. Histopathologic data, including immunohistochemistry findings and MRI data according to the BI-RADS lexicon, were reviewed. The association between MRI or histopathologic findings and BRCA mutations was analysed.

Results: BRCA-positive familial breast cancers had a higher number of IDCs with high nuclear grade and lymph node metastasis (all P<0.05), while the BRCA-negative group had a significantly lower Ki-67 index (P<0.001). BPE on MRI was found to be significantly lower for BRCA mutations of familial breast cancer (P=0.024). BRCA1 carriers tended to exhibit the triple-negative phenotype with a more benign shape and margin (P=0.006 and 0.019), whereas BRCA2 mutations were associated with the luminal phenotype and more malignant features.

Conclusions: BRCA mutation carriers had a significantly higher number of IDCs with more aggressive cancer, and BRCA-negative cancers had low proliferation levels. Background features on MRI may help to identify BRCA status, while tumour characteristics can differentiate the BRCA1/2 mutation status, consistent with the differences in their clinicopathologic features.