Diagnosis of Pathological Complete Response by Minimal Invasive Biopsy After Neoadjuvant Chemotherapy in Breast Cancer

Can a Pathological Complete Response in the Breast be Diagnosed by Vacuum-assisted, Ultrasound Guided Minimal Invasive Biopsy After Neoadjuvant Chemotherapy in Breast Cancer Patients? A Proof of Concept From a Prospective Cohort Study

The study aims to evaluate the ability of representative vacuum-assisted minimal invasive biopsy (VAB) to diagnose pathological complete response (pCR=ypT0) in breast cancer patients after neoadjuvant chemotherapy (NACT).

Neoadjuvant chemotherapy (NACT) is an increasingly used approach for patients with locally advanced and primarily inoperable breast cancer or for patients with potentially chemosensitive tumors. In clinical routine surgical treatment follows the pre-operative chemotherapy. However, recent studies have demonstrated that shrinking tumors need less surgical treatment indicating that patients with pCR could potentially be spared of surgery in the future.

Up to now, prediction of pCR after NACT, i.e. diagnosing a pCR without surgery, is based on tumor biology at diagnosis, the applied NACT regimen and breast imaging results; all with mediocre accuracy. This prospective, monocenter diagnostic trial aims to explore if minimal invasive biopsies (MIB) might overcome this diagnostic challenge.

From September 1st, 2014 to February 15th, 2015 the investigators performed ultrasound guided vacuum-assisted minimal invasive biopsy (VAB) on 50 breast cancer patients after NACT and directly prior to surgery. To analyse VAB pathologically results were categorized as follows: residual vital tumor cells (invasive, in situ, both, lymphangiosis carcinomatosous) present, (significant parts of) the tumor bed present, neither vital tumor cells nor (significant parts of) the tumor bed (indicating a non representative VAB). The results were compared to those of the pathological examination of surgical specimen.

Inclusion Criteria:

The investigators included patients

• after neoadjuvant chemotherapy (NACT) according to the NACT protocol
• with at least one detectable mass / marker after NACT in ultrasound
• with cT1c-cT4a-c tumors
• after informed consent
• with unilateral or bilateral primary breast cancer, confirmed histologically prior to chemotherapy
• with known grading, ER/PgR/HER-2neu- and Ki-67 status
• with breast ultrasound, mammography (and breast MRI where necessary) before and after NACT
• clinical / imaging partial or complete response to NACT

Exclusion Criteria:

The investigators excluded patients from the study with

• NACT <12 weeks because of termination due to progressive disease, massive adverse events or patient wish
• non-detectable mass in ultrasound / dislocation of marker (> 10mm distance to the initial lesion)
• cT4d stage (inflammatory breast cancer)
• M1 stages
• stable disease according to a multimodal assessment of ultrasound, mammography and breast MRI (if available) according to RECIST