PD02-04: A Randomized, Prospective, Multicenter Study of the Impact of Intraoperative Margin Assessment with Adjunctive Use of MarginProbe vs. Standard of Care.
Authors: Schnabel F , Tafra L ,   The MarginProbe Study Group
Published: June 2012

Background: The current practice of breast conserving surgery (BCS) involves intraoperative margin assessment according to the surgeon's gross assessment and judgment. The failure of this intraoperative assessment has been associated with a 20–30% reoperation rate to assure negative margins. MarginProbe (Dune Medical Devices) was developed to provide real-time assessment of lumpectomy specimens to evaluate for the presence of disease at the surgical margins. A 21-center international pivotal study was conducted to determine if adjunctive use of MarginProbe can enable surgeons to identify positive margins intraoperatively, resulting in fewer patients who are candidates for re-excision procedures.

Methods: 664 women with non-palpable lesions undergoing lumpectomy for DCIS and invasive cancer were enrolled and 596 randomized (1:1) in the operating room following standard of care (SOC) lumpectomy. In the device arm, MarginProbe was used to assess all surfaces of the lumpectomy specimen and positive readings required additional resections. All specimens were inked in the operating room by the surgeon. All specimens were examined to verify excision of the target lesion intraoperatively. Pathologists were blinded to study arm. Additional surgeries to re-excise involved margins were performed per each individual site criteria. Patients were followed for 2 months following surgery; additional procedures were documented. Safety was assessed by reports of adverse events.

Results: No safety concerns were raised. Of the 298 patients in each arm, 55% (163/298) patients in the device arm (D) and 49% (147/298) in the control arm (C) had at least one positive margin on the main lumpectomy specimen (≤ 1mm). Surgeons’ ability to identify and resect all positive margins per patient was significantly improved with device use (D: 72% (117/163), C: 22% (33/147); p &lt; 0.0001). Following lumpectomy, the number of patients having positive margins due to failed intraoperative assessment (excluding skin or fascia) was reduced by 57% in the device arm (D: 42/298(14%), C: 98/298(32.8%), p&lt;0.0001), leading to a 50% reduction in re-excisions for this group (D: 31/298 (10.4%), C: 62/298 (20.8%); p=0.001). There was no significant difference in tissue volume removed (D: 93cc, C: 85cc; 25cc non-inferiority delta, p &lt;0.0001). Normalized to baseline breast size, tissue volume in the device arm was non-inferior to the control arm (D: 15.1%, C: 12.5%, 5% non-inferiority delta, p &lt;0.0001). For patients having at least one positive margin prior to intraoperative assessment, there was a trend in the device arm towards smaller average tissue volume resected to achieve clear margins (D: 99cc, C: 108cc; p=0.6).

Conclusions: Adjunctive use of MarginProbe during BCS significantly improved surgical outcomes by improving surgeons’ ability to identify and immediately resect positive margins, reducing the number of patients requiring re-excision. Overall tissue volume removed was not statistically different in the two arms. Patients in the device arm who had positive margins prior to intraoperative assessment had less average tissue volume removed and required fewer re-excisions to achieve appropriate margins.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PD02-04.