Presence of crown-like structures in breast adipose tissue; differences between healthy controls, BRCA1/2 gene mutation carriers and breast cancer patients

Purpose: Crown-like structures (CLS) in breast adipose tissue are associated with inflammation and a potential factor in breast cancer behaviour. Whether this effect varies between breast cancer subtypes and is influenced by BMI and BRCA mutation status is presently unknown. Therefore, we compared CLS presence between adipose tissue of healthy controls, BRCA1/2 gene mutation carriers and breast cancer patients, and assessed the relation of CLS with clinical outcome in breast cancer patients.

Methods: Immunohistochemical staining for CD68 was performed on breast adipose tissue sections of 48 healthy controls, 78 BRCA1/2 gene mutation carriers and 259 breast cancer patients. CLS presence and index (CLS/cm²) were correlated with BMI, BRCA status, tumour presence, intrinsic tumour subtype and tumour characteristics. Associations with clinical outcome were assessed.

Results: CLS were more often present in breast cancer patients compared to BRCA carriers and healthy controls. CLS presence was associated with the presence of breast cancer and high BMI. CLS were more often present in Luminal-B-like tumours compared to the other subtypes. No correlations between CLS and BRCA status or age was found. In TNBC, CLS were related to lymphovascular invasion. No association with survival was found.

Conclusion: In conclusion, CLS were more frequently present in breast adipose tissue of breast cancer patients compared to BRCA1/2 gene mutation carriers and healthy controls. Furthermore, our study provides evidence of the association between obesity and presence of CLS. The prognostic significance and impact on clinical outcome of differences in CLS numbers should be further assessed in prospective studies.