Margin Optimisation Using Z-axis Assessment With Real-time Tomosynthesis (MOZART Study).

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Brief Summary

(Plain-language, patient-facing; within 5,000 characters)

Breast-conserving surgery is commonly performed to remove early-stage breast cancer or ductal carcinoma in situ (DCIS). During surgery, the goal is to completely remove the tumour with a clear margin of normal tissue around it. If cancer cells are found at the edge of the removed tissue (a "positive margin"), patients may need a second operation (re-excision). Re-excision can delay further treatment, increase patient anxiety, and increase healthcare costs.

To help assess margins during surgery, surgeons use specimen imaging. Standard practice involves two-dimensional (2D) specimen mammography, usually performed in the radiology department. This requires temporary transfer of the specimen out of the operating theatre and provides limited depth information.

The MOZART study is evaluating whether three-dimensional (3D) digital breast tomosynthesis, performed in the operating theatre using the Mozart system, improves margin assessment compared to standard 2D specimen mammography.

Patients undergoing breast-conserving surgery at Beaumont Hospital who agree to participate will be randomly assigned (like flipping a coin) to one of two groups:

Standard 2D specimen mammography (current standard practice), or

3D digital breast tomosynthesis performed in theatre.

In both groups, the operating surgeon will review the images during surgery and decide whether additional tissue needs to be removed. The final margin status will be determined by routine laboratory analysis after surgery.

The main goal of this study is to compare the rate of positive margins between the two imaging methods. Other outcomes include the need for additional surgery, operating time, and overall workflow efficiency.

The results of this study may help determine whether intraoperative 3D imaging improves surgical outcomes and reduces the need for re-excision in patients undergoing breast-conserving surgery.

Detailed Description

(Technical, structured, avoids repeating registry fields; within 32,000 characters)

Background and Rationale

Breast-conserving surgery (BCS) is a standard surgical treatment for early-stage invasive breast cancer and ductal carcinoma in situ (DCIS). Achieving clear surgical margins is essential to minimise local recurrence risk and reduce the need for re-excision. Despite current intraoperative assessment techniques, reported positive margin rates range from 15-20%, and a substantial proportion of patients require additional surgery.

Intraoperative specimen imaging is used to guide margin assessment. Standard practice involves 2D specimen mammography performed in the radiology department. Limitations of this approach include:

Specimen transport outside the operating theatre Potential workflow delays Limited three-dimensional assessment of tumour-margin relationships Difficulty interpreting complex lesions or microcalcifications Digital breast tomosynthesis (DBT) provides three-dimensional imaging through multiple reconstructed slices. The Mozart 3D Specimen Radiography System enables intraoperative DBT imaging directly within the operating theatre. This may improve visualisation of margins and allow more accurate real-time surgical decision-making.

Prospective observational data suggest improved diagnostic accuracy with intraoperative DBT compared to standard specimen mammography. However, high-quality randomised controlled trial data are limited.

Study Design

The MOZART study is a prospective, single-centre, open-label, parallel-group randomised controlled trial conducted at Beaumont Hospital.

Eligible patients undergoing breast-conserving surgery will be randomised in a 1:1 ratio to:

Standard intraoperative 2D specimen mammography (control group), or

Intraoperative 3D digital breast tomosynthesis using the Mozart system (intervention group).

Randomisation will be computer-generated. Surgeons and participants will not be blinded due to the nature of the intervention. Histopathologists assessing final margin status and data analysts will be blinded to group allocation.

Intervention Procedures Control Group

Specimen imaging will be performed in the radiology department using standard 2D mammography. The operating surgeon will review images and determine whether additional excision is required.

Intervention Group

Specimen imaging will be performed in theatre using the Mozart 3D digital breast tomosynthesis system. The surgeon will assess reconstructed tomosynthesis images in real time and determine whether additional excision is required.

In both groups, standard surgical technique and postoperative management will not be altered.

Outcomes

The primary outcome is the rate of positive surgical margins on final histopathological assessment.

Positive margins are defined according to contemporary national and international guidance as:

Invasive carcinoma at or within 1 mm of the inked margin; or DCIS within 2 mm of the margin.

Secondary outcomes include:

Re-excision rate Operative time metrics Time from specimen removal to imaging review Theatre workflow efficiency Cost-effectiveness analysis

• Re-Excision Rate [Time frame: Within 3 months after index surgery]
• Time From Specimen Removal to Imaging Review [Time frame: Intraoperative (day of surgery)]
• Time From Specimen Removal to Skin Closure [Time frame: Intraoperative (day of surgery)]
• Total Operative Time [Time frame: Intraoperative (day of surgery)]
• Cost-Effectiveness Analysis [Time frame: At study completion (after all participants have completed follow-up)]