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Concordance of preoperative breast MRI finding with definitive postoperative pathology report, after neoadjuvant systemic treatment in patients with breast cancer

Neoadjuvant, i.e. preoperative, systemic antineoplastic treatment (NAT), in patients with breast cancer enables in vivo monitoring of tumor response to applied therapy, tailoring treatment in real –time accordingly, sparing surgical procedures, better quality of life for patients and implies better patient survival for particular patient, if a pathological complete response (pCR) to treatment is achieved. Use of MRI in monitoring response to NAT has shown in various studies sensitivity and specificity of at least 70% in the detection of residual disease, with a high positive and negative predictive value. Studies have shown higher accuracy in predicting pCR in HER2 positive tumors, and a higher rate of false negative results in HER2 negative tumors. Here we report findings of our pilot project where we tested the accuracy of the MRI, and the concordance of preoperative MRI findings after NAT, with the definitive pathology report after the surgery was performed, in breast cancer patients with different disease biology, in the real clinical practice. The focused pathological supstrate was the primary tumor in the breast. For the simplicity of this pilot analysis, we did not include here the status of the axilla, which will be included in our larger analysis pending. We performed our analysis on a cohort of 200 breast cancer patients who underwent NAT, in our institution, University Hospital for Tumors, in Zagreb, Croatia. Median age of the analyzed patient cohort was 62 years. The representation of individual breast cancer intrinsic subtype surrogates was as follows: HER2 nonluminal tumor 23.5% (47/200), triple negative breast cancer 21.5% (43/200), luminal HER2 positive 22.5% (45/200) and luminal HER2 negative 32.5% (65/200). According to MRI of the primary tumor in the breast, radiological complete response (rCR) to NAT was achieved in 46.5% (93/200) of patients, and the finding of residual tumor was described in 53.5% (107/200) of patients. Postoperatively, pathology report of the primary breast tumor showed pCR in 29% (58/200) of patients, and residual disease in 71% (142/200) of cases. The overall concordance of MR and pathology reports was 62.4% in the assessment of complete response, and 75.35% in the assessment of residual disease. Analyzed according to subgroups, results are as follows: in the cohort of patients with HER2 nonluminal tumors, concordance of MRI and pathology report in the assessment of complete response was 88%, while for residual disease concordance was 70% ; in the cohort with triple- negative breast cancer patients, concordance of MRI and pathology report in the assessment of complete response was 83%, and residual disease 87.8% ; in the group with luminal HER2-positive breast cancer concordance of MRI and pathology report in assessing complete response, as well as residual disease, was 97% ; while in the group with luminal HER2-negative breast cancer, concordance of MRI and pathology report findings in assessing complete response was only 50.5%, and residual disease 77%. Results of our analysis showed relatively high overall concordance between MRI and pathology findings, which is in line with results of large studies worldwide and confirms MRI as a good method in monitoring response to NAT in breast cancer patients. By subgroup analysis, patients with luminal HER2-negative tumors are distinguished. This group has the lowest prevalence of complete response overall, as well as the lowest concordance of MRI and pathology report findings in the detection of these cases. This confirms the weaker response of this type of tumor to neoadjuvant treatment, but also indicates the need for additional caution when analyzing MRI findings in these patients, as well as for considering additional diagnostic arsenal, complementing the standardly – utilised MRI.

breast cancer ; neoadjuvant systemic antineoplastic treatment (NAT) ; magnetic resonance imaging (MRI)

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