A series of OCT images acquired across a three-dimensional surgical margin that is positive for tumor.
It has been more than six years since Beckman Institute researcher Stephen Boppart first began imaging tissue samples using an optical method he had been developing for breast cancer diagnosis. The first paper reporting on a clinical study of the validity of Boppart’s method is the cover story in the Nov. 15 issue of the American Association of Cancer Research’s journal Cancer Research.
The paper, titled Intraoperative Evaluation of Breast Tumor Margins with Optical Coherence Tomography, appears as the cover story online in the journal and the print edition and reports that the system has in fact proven accurate and viable as an operating room diagnostic tool for the important mission of assessing tumor margins in breast cancer surgery.
“It’s been one of the longer investigations that we’ve done because these are clinical studies,” Boppart said. “It’s very rewarding because this is where we wanted to be all along. But we also recognize this is just a start. We’ve got a lot more work to do and a lot more questions to ask.”
Boppart is senior and corresponding author of the paper, while lead author is Freddy Nguyen of Boppart’s research group. Other co-authors include Boppart research group members as well as medical personnel at Carle Foundation Hospital, where the clinical studies were conducted.
It’s very rewarding because this is where we wanted to be all along. But we also recognize this is just a start. We’ve got a lot more work to do and a lot more questions to ask.
– Stephen Boppart
This first clinical study involved using, for the first time anywhere, an optical coherence tomography (OCT) imaging system as an intraoperative (within the operating room during the procedure), real-time diagnostic tool for assessing tumor margins in breast tissue. The paper reports that, when correlated with post-surgical findings of pathologists, the accuracy of the OCT system’s results were validated by the histology data.
The authors report that the intraoperative OCT system showed 100 percent sensitivity and 82 percent specificity for determining margin status, either positive or negative, for cancerous cells. Boppart said that a positive margin means there are tumor cells at a cut surface, a close margin means they are within one millimeter of that surface, and a negative margin that they are greater than one millimeter away.
“The fact that we have 100 percent sensitivity means we were able to detect 100 percent of the time when disease is present, when there is a positive margin,” Boppart said. “The 82 percent specificity means when there is a negative margin, we are able to call it negative 82 percent of the time. So I’m very pleased with those numbers.”
The ongoing project has had more than 75 participants to date, with 37 patients involved in this study, including 17 in a patient training set and 20 patients – all of whom had a biopsy-proven breast tumor – for the study of the intraoperative procedure.
The advantages of the OCT system, as the authors write, are that it “provides surgeons the ability to assess margin status in real-time, complementing current gross visual examination, potentially reducing the number of positive/close margins discovered post-operatively, and thereby reducing the need for additional surgical procedures.”
Boppart, who is also an M.D., Co-chair of Beckman’s Integrative Imaging research theme, and professor in the departments of Electrical and Computer Engineering, Bioengineering, and Medicine, at Illinois, said the ability to quickly and accurately assess tumor margins in the operating room is an important capability the OCT system brings to the fight against breast cancer.
“I don’t think it will ever replace histology as the gold standard,” Boppart said. “Histology, with its resolution and staining, is really what is used to make the final diagnosis. However, histology has limits in terms of how much it can sample, how long it takes, and how much it costs.”