breast cancer

Optics may speed breast cancer diagnosis


Above, a series of images acquired with a new system that uses optical coherence tomography, a light-based technology, to analyze biological tissues, such as lumpectomies, during a surgical procedure. The images show a positive result, suggesting the presence of a tumor. (Credit: Freddy Nguyen, Steven Adie, Stephen Boppart, and Darren Stevenson)

U. ILLINOIS (US)—Waiting for laboratory results is often one of the most stressful aspects of a breast cancer diagnosis. A new optical imaging system aims to ease that stress by giving doctors performing lumpectomies real-time information on breast cancer tissue margins while still in the operating room.

Developed by Stephen Boppart, professor of electrical and computer engineering, bioengineering, and medicine, at the University of Illinois, the imaging system uses optical coherence tomography—a light-based technology for imaging subsurface biological tissue—to provide high-resolution, micron-scale images.

Boppart put his system to the test through a collaborative study involving his laboratory at Illinois’s Beckman Institute and a local hospital.

The study, which involved 37 breast cancer patients, used for the first time anywhere, an optical coherence tomography, or OCT, imaging system as an intraoperative (within the operating room during the procedure), real-time diagnostic tool for assessing tumor margins in resected breast tissue.

Results show that, when correlated with post-surgical findings of pathologists, the accuracy of the OCT system’s results were validated by the histology data.

The intraoperative OCT system showed 100 percent sensitivity and 82 percent specificity for determining margin status, either positive or negative, for cancerous cells.

Boppart says 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 explains.

“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.”

Boppart says 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 stresses. “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.”

The advantages of the OCT system 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.”

Histology assessments performed after surgical lumpectomy procedures find positive margins between 10 percent and 30 percent of the time, Boppart says. With histological methods, tumor margins are often under-sampled, sometimes missing positive margins, and often with a return to the operating room for a second resection procedure for the patient.

“And this is found a day later after the surgery has ended,” Boppart says. “It means that the patient has to come back for another procedure, with all the risks and costs associated with that, and all the anxiety.

“Another downside for the patient is if there are any tumor cells left behind. These patients are likely to relapse, as there is a fairly high local recurrence rate of tumors that grow back in that area.”

Boppart says that by using the OCT system, “intraoperative identification of positive margins will decrease the need for additional surgical procedures and the rate of local recurrence in breast cancer patients.”

The paper detailing the research appeared as the cover story in the American Association of Cancer Research’s journal Cancer Research.

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