Three-dimensional bREast ultraSound for resPOnse evaluation of Neo-aDjuvant chEmotheRapy; an adequate replacement for MRI in breast cancer patients? (RESPONDER trial)

Neoadjuvant chemotherapy (NAC) enables a tumour response evaluation during treatment and therefore an evaluation of therapy efficacy in vivo. An adequate response can downstage a tumour enabling breast conservative surgery (instead of mastectomy). In case of tumour progression the chemotherapy regimen can be changed (if applicable) or immediate breast surgery can be scheduled. Tumour response evaluation therefore directly influences treatment decisions. Breast MRI is considered gold standard to evaluate tumour response in breast cancer patients. However breast MRI is costly, invasive and time consuming. Thereby, reported concordance for MRI tumour size compared to histopathological tumour size (considered gold standard) varies between studies evaluating breast cancer patients with and without NAC. Comparable results are published for ultrasonography (handheld/ 2D). Handheld ultrasonography is however very operator-dependent and therefore non-reproducible. The Automated Breast Volume Scanner (ABVS) is a three-dimensional ultrasonography technique which scans the breast in an automatic and standardised manner. Previous studies reported superior accuracy for breast tumour-size prediction. The ABVS is a non-invasive, quick and affordable technique as compared to a breast MRI and importantly the preferred technique over breast MRI for patients. Thereby, tumour volume measured on three-dimensional ultrasonography showed an excellent association with histopathological tumour volume. We hypothesise that the ABVS is comparable to the breast MRI in response evaluation during NAC in breast cancer patients.

All woman, aged above 18 years, with an adenocarcinoma of the breast visible on ultrasonography and scheduled for NAC in the Academic Breast cancer Centre (Rotterdam, the Netherlands) will be included. Ultrasonography data will be obtained using the ABVS in addition to the breast MRI’s as obtained in the standard care. A post-NAC or second response evaluation using the ABVS will be performed in all participants irrespective of the use of a possible post-NAC MRI. Post-NAC ABVS measurements will be correlated to the histopathological evaluation to study the accuracy of the three-dimensional ultrasonography in the prediction of pathological complete response (pCR). The primary outcome is the concordance between the longest tumour diameter during response evaluation, accessed and compared by the conventional MRI and the ABVS. Secondary outcomes are the concordance of the volume response evaluation of the conventional MRI and the ABVS, the diagnostic accuracy of the ABVS to predict a pCR, patients preferences (as measured by a questionnaire) and the costs of the response evaluation by the MRI as compared to the ABVS.

In summary this study aims to prove that the three-dimensional ultrasonography is at least equal to breast MRI when assessing tumour response in patients treated with NAC include the prediction of a pathologic complete response in vivo.

We hypothesise that the ABVS is comparable to the breast MRI in response evaluation during NAC in breast cancer patients.

T0: Pre-NAC MRI + additional ABVS (inclusion)

T1: Mid-NAC MRI + additional ABVS

T2: (Post-NAC MRI +) additional ABVS

Postoperative compared to histopathology

Performing a three-dimensional ultrasonography in addition to the breast MRI (standard of care) to evaluate the tumour response during neoadjuvant chemotherapy in breast cancer patients. The three-dimensional ultrasonography will be obtained using the Automated Breast Volume Scanner (ABVS – Siemens Acuson s2000), an automated ultrasonography technique. The response evaluation by ABVS will be compared to the response evaluation measured by breast MRI with the histopathologic evaluation as gold standard.