Towards omitting breast cancer surgery in patients without residual tumor after upfront chemotherapy.

Improvements in PST for breast cancer patients have led to increasing rates of pCR. However, until now no imaging modalities (or techniques) have been described to reliably identify patients with a pCR of the breast. Therefore, many patients still encounter overtreatment since patients undergo surgery of the original tumour area to confirm the absence or presence of pCR after PST.



The ultimate aim of our study is to eliminate surgical treatment in breast cancer patients achieving pCR after PST, thus preventing overtreatment and improving quality of life. We will achieve this aim by identifying patients with pCR following PST without surgical removal of (part of the) breast.
We will assess the value of biopsies of the breast in determining pathologic response to PST, in patients with rCR on MRI.



The MICRA trial is a 3 year observational prospective cohort study. Patients included are patients who are diagnosed with invasive breast cancer and showed rCR on MRI after PST.
In these patients, eight ultrasound-guided core biopsies (14G needle) are performed at the site of the original tumour bed, which is marked with before PST (with a iodine seed, clip or hydro marker). Immediately hereafter, breast surgery is performed. Pathology results of biopsies and surgical specimens are compared, to determine the accuracy of this diagnostic procedure. Results from these biopsies will be combined with data on imaging, patient and tumour characteristics.



For treatment of the breast these results will define 2 patient groups:

- Presence of residual disease can be reliably predicted on MRI without obtaining post-PST pathology

- Presence/absence of pCR needs to be assessed by biopsies, and surgery may be omitted if biopsies show no residual tumour

We hypothesize that in breast cancer patients with radiologic complete response (rCR) on MRI after primary systemic treatment (PST), a pathologic complete response (pCR) can reliably be predicted with use of multiple biopsies after PST.

4-2016: MEC approval

4-2016: Start patient accrual

12-2016: Submit pilot and study design for publication

4-2017: Start designing national registration study

12-2017: Interim analysis and report

4-2019: Finish patient accrual

4-2019: Submit study results for publication

In all patients receiving PST, a marker is placed at the center of the tumor area before the start of PST. Adequate position of the marker is confirmed by mammography and/or ultrasound.
After completion of PST, a MRI is performed to evaluate radiologic response. In patients with a radiologic complete response, eight biopsies of the original tumor bed are obtained, just before surgery when patients are under general anaesthesia (to minimize patient discomfort). The biopsies are obtained with use of a 14-gauge core needle. Four biopsies are obtained at <0.5 cm distance of the marker and 4 biopsies are obtained at 1.0-1.5 cm distance of the marker. Immediately after collection of the biopsies, conventional surgery is performed, which may consist of breast conserving surgery or mastectomy.
Pathology results of the biopsies and resected specimens are compared, to assess whether pCR can be reliably determined on post-PST biopsies.