Serial MRI scans help in assessing early response to neoadjuvant chemotherapy and tailoring breast cancer treatment

Tailoring neoadjuvant chemotherapy (NAC) during breast cancer treatment is performed to improve overall tumour response, with increasing evidence to support its role. This study evaluates our breast unit's experience in MRI assessment of tumour response as an aid in tailoring NAC.

This is a retrospective study of patients treated with NAC for breast cancer between 2005 and 2009 who underwent MRI to assess tumour response. Response to NAC was monitored before NAC and after 2 and/or 4 cycles of anthracycline and cyclophosphamide (AC) chemotherapy. Taxane was substituted for AC if MRI response was deemed inadequate. Tumour response on last MRI was correlated with final pathology against different tumour subtypes and in inflammatory tumours. Strength of agreement was measured using Kappa analysis. Potential predictive factors for MRI response were assessed for significance.

166 tumours were assessed with serial MRI scans. MRI showed high sensitivity rate (93.1%) in predicting response to NAC particularly for tumours showing partial (PR) or complete (CR) response on pathology (p < 0.001) with fair agreement on Kappa analysis (K = 0.31). MRI seems more accurate in triple negative, HR+/HER2+ and high-grade tumours. Early identification of non-responders on MRI resulted in early tailoring of NAC, with improved rates of tumour response seen in 74.2% following switching NAC. Logistic regression showed that PR or CR observed on MRI after 2 NAC cycles significantly predicted pCR (p < 0.001).

Serial MRI can be used to assess patterns of tumour response to NAC. This study shows that tailoring NAC according to pattern of response can improve overall tumour response rates.