Abstract P3-04-09: 3-dimensional intraoperative analysis of screen-detected breast cancers reduce re-excision rates

Introduction: Breast conserving therapy, has generally been accepted as treatment of choice for early invasive breast cancer. However adequate local control depends on obtaining negative margins and receipt of radiation In 20-30 % of patients with breast conserving surgery a second re-excision procedure is due to tumor-positive margins at histopathology. Margins re-excision rate are variable across the countries. Mean re-excision rate of 17.2% across units in UK. Intraoperative specimen radiography,used to evaluate partial mastectomy specimens ensure that the lesion is adequately removed.

Objective: to determine whether 3D-intraoperative imaging better predicts margin status and reduces the re-excision rate than conventional 2D imaging.

Methods: Retrospective study comparing two cohorts of patients 360 screen-detected breast cancer (2D cohort). April 2015 to March 2018

300 screen-detected breast cancer (3D cohort) April 2018 to March 2021

Royal Cornwall Hospital (RCHT) introduced a 3D intraoperative system for all cases in April 2018

Prior to the introduction of 3D intraoperative imaging at RCHT the re-excision rate was stable at approximately 15%.

All patient had undergone preoperative digital mammogram and ultrasound.

All patients had core biopsy diagnosis

All malignancies were localised with ROLL (Radio-guided occult lesion localization) techniques.

All wide local excision were performed by 5 fully trained oncoplastic breast surgeons (similar distribution within the two cohort)

Specimen radiograph was performed intraoperatively using:

2D x-ray device (Faxitron system; Trident Hologic, Marlborough, MA) or

3D tomosynthesis (Mozart system; Kubtec Medical imaging, Stratford,CT).

For both methods of assessment,specimen was placed in the device and auto exposed without any compression of tissue.

All specimens were marked with orienting sutures and clips according to local protocol.

All specimens were painted in theatre by the operating surgeon.

All specimens were examined by the same pathologists.

No change in margin protocol for 12 years(already compliant to ABS guidelines)

• A clear margin for invasive cancer was defined as tumour found within 1mm of

margin. For ductal carcinoma in situ (DCIS), a margin was classified as positive if ink

on tumour, was classified as close ink is found in under 2 mm from tumour and as

negative if more or equal to 2 mm, in accordance with NICE guidelines. (22)

Statistical Analysis:

• The study compares patient demographics, histology, and re-excision rates between 2D and 3D

• Descriptive and comparative statistics are be calculated for all collected data TABLE 1:

3D/2D RR 0.59 (P:0.01), CI 0,3369-09068, Z -2.3473, P 0.0189

Conclusions: The use of intraoperative 3D specimen X-ray reduced the relative risk of re-excision rate by 41% (P=0.01) without any negative impact on other parameters.

Table 1: Results 3D intraoperative imaging versus 2D intraoperative imaging

Citation Format: Jo Mondani, Hamza Arabiyat, Stavroula Kastora, Mona Sulieman, Imran Abbas, Polly King, Rachel English, Iain Brown, Miklos Barta, Nicola Jackson, Philip Drew. 3-dimensional intraoperative analysis of screen-detected breast cancers reduce re-excision rates [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-04-09.