Ultrasound-Assisted Tumor Surgery in Breast Cancer - A Prospective, Randomized, Single-Center Study (MAC 001)

Breast-conserving therapy is associated with a risk of tumor-involved margins. For intraoperative orientation, non- palpable or indistinctly palpable lesions are wire-marked prior to surgery. Ultrasound-guided surgery has the potential to reduce the number of tumor-involved margins. In the MAC 001 trial we evaluated ultrasound-guided breast-conserving surgery compared to wire-guided surgery with regard to free tumor margins, duration of surgery and resection volume.

In this randomized, prospective, single-center controlled trial, patients with ductal invasive breast cancer were recruited for either ultrasound-guided or wire localization surgery. Primary outcomes were tumor-free resection margins, the reoperation rate and the resection volume in each group. The results were analyzed by intention to treat. The trial was registered under ClinicalTrials.gov NCT02222675.

56 patients were assessed, and 47 patients were evaluated in the trial. 93 % (25/27) of the patients in the ultrasound arm had an R0 reoperation compared to 65 % (13/20) in the wire localization control arm. This result was statistically significant (p = 0.026). No statistical difference was found for the resection volume or the duration of surgery between the two arms. No major complication was seen in either arm.

Ultrasound-assisted breast surgery significantly increases the possibility of tumor-free margins and therefore reduces the risk of reoperations. Breast surgeons should be trained in ultrasound and ultrasound should be available in every breast surgery operating room.