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Did they “get it all”? News release describes device that might give real-time answer to cancer surgeons

CHAMPAIGN, Ill. – A new surgical tool that uses light to make sure surgeons removing cancerous tumors “got it all” was found to correlate well with traditional pathologists’ diagnoses in a clinical study, showing that the tool could soon enable reliable, real-time guidance for surgeons.

The interdisciplinary research team led by Stephen Boppart, a University of Illinois professor of electrical and computer engineering and of bioengineering, performed the study on 35 patients with breast cancers at the Carle Foundation Hospital in Urbana, Illinois. The results appear in the journal Cancer Research.

One difficult but crucial determination for surgeons and tissue pathologists is figuring out where a tumor ends. A solid tumor may be easily identifiable, but the tissue around the main body of the tumor, known as the margin, may contain cancerous cells as well. Because of this, excess tissue surrounding the tumor is typically removed, but the question lingers of whether any cancer cells remain to re-emerge later as tumors.

“In almost all solid-tumor surgeries, there’s a question of margins,” said Dr. Boppart, who also is a medical doctor. “Typically, surgeons will remove the tissue mass that contains the tumor and will send it to the lab. The pathologist will process, section and stain the tissue, then examine the thin sections on microscope slides. They look at the structure of the cells and other features of the tissue. The diagnosis is made based on subjective interpretation and often other pathologists are consulted. This is what we call the gold standard for diagnosis.”

The new device is a hand-held probe based on a technology called optical coherence tomography (OCT) that uses light to image tissue in real time. Cancer cells and normal tissue scatter light differently because they have different microstructural and molecular features, Boppart said, so OCT gives physicians a way to quantitatively measure the cellular feature of a tumor. Surgeons can pass the OCT wand over a section of tissue and see a video on a screen, with no special chemical stains or lengthy tissue processing required.

“In many cases, you can’t tell the difference between cancer cells and normal tissue with the naked eye, but with OCT they’re very different,” said Boppart, who also is affiliated with the Beckman Institute for Advanced Science and Technology at the U. of I.

In the clinical study, surgeons treated patients according to the standard surgical procedure, but OCT data were collected from the margin of the tumor cavity and the margin of the removed tissue mass during surgery so that the results could be compared later. The study found that the OCT device analysis identified the differences between normal and cancerous tissue with 92 percent sensitivity and 92 percent specificity. They also found that the way that OCT spotted cancer in the removed tissue was closely correlated with the results from the postoperative pathology reports, which often came days later.

“For the first time, this study demonstrates the use of OCT for imaging tumor margins within the tumor cavity, in the patient, during surgery,” Boppart said. “It is likely better to check to see if any residual tumor cells might be left behind, rather than checking the tissue mass that was taken out. Then, the surgeon can intervene immediately.”

The researchers will continue clinical studies with the OCT device, looking at other types of solid-state tumors. Diagnostic Photonics, a start-up company Boppart co-founded that also collaborated on the study, is commercializing the OCT probe technology for broader use.

“Ultimately, new technological innovations like this in medicine and surgery are going to improve our health care and save lives. That’s when this work will be most rewarding,” Boppart said.

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The National Institutes of Health supported this work.

Editor’s notes: Editor’s note: To reach Stephen Boppart, call 217-244-7479; email:boppart@illinois.edu.

The paper “Real-time imaging of the resection bed using a handheld probe to reduce incidence of microscopic positive margins in cancer surgery” is available online athttp://cancerres.aacrjournals.org/content/75/18/3706.full.

Surgical probe seeks out where cancer ends and healthy tissue begins

Our Review Summary

The experimental light probe. Credit University of Illinois at Urbana-Champaign.

The experimental light probe. Credit University of Illinois at Urbana-Champaign.

This news release describes the results of a small clinical “proof of concept” trial designed to blind-test the reliability and accuracy (i.e. sensitivity and specificity) of a hand-held light-only probe that surgeons might use to accurately determine how much tissue beyond a visible tumor should be removed during cancer surgery to help contain the disease. The release does a praiseworthy job of pointing out right away that the goal of the study was to measure the performance of the instrument, called an optical coherence tomography (OCT) device, against the “gold standard” practice of surgically collecting tissue from both the tumor and the “margins” around the tumor cavity, and sending both to a pathology lab for definitive diagnosis and evidence  that surgeons “got it all.” The release would have benefited from more information about the sensitivity and specificity of the results among the patient groups. And it didn’t describe what it is, exactly, that OCT identifies — i.e. the mixed and disorganized microscopic tissue structures that are the markers of malignancy. But overall, the release does make clear the potential of the technology without over-promising a timetable for clinical use. And it does an admirable job of disclosing the financial interest in commercialization of the device by one of the investigators. Readers will be mostly well informed by this release.

 

Why This Matters

During surgery to remove a solid tumor, some tissue around the tumor is also removed. A pathologist takes the tumor with surrounding tissue and stains it with ink so that the outer edges, or margins, can be seen under a microscope. “Negative margins” means the outer edge is free of cancer cells, whereas “positive margins” indicates that there were cancer cells at that outer edge. To reduce the chances of recurrence, surgeons seek “negative margins” when removing a tumor.  However, such “gold standard” pathology analyses cannot usually be done definitively while a patient is still on the operating table, so if margins are not determined to be clean or clear or wide enough, repeat trips to the operating room may be necessary, with all of their attendant risks and complications. Thus, devices that may help surgeons in real time assess the outer margins by accurately measuring the cellular structures of a tumor would likely be welcomed not only by patients and their surgeons, but possibly also by payers, by reducing the probability of repeat procedures and complications.

Criteria

Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

Although the study was not designed to assess relative costs of gold standard histology and OCT. the release would have helped both the news value of the study and the reader’s understanding of technological innovation if it had included some estimate of costs associated with use of the device. Operating room time is incredibly expensive, and any procedure that adds significant time will also add significant cost. In addition, prolonging any surgical procedure will extend the amount of time that the patient is under general anesthesia. We suspect (based on experience with the Dune Medical device, which is similar) that the procedure doesn’t take more than about 5-10 minutes, but the release could have made this clear. Another issue could be the cost of the device to the facility. There is no CPT (billing) code for this procedure, so when commercially available, the cost likely cannot be passed along to the patient. Hospitals may not be interested in purchasing this equipment as they may not be able to get reimbursed for the cost of the device.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Satisfactory

The release describes the accuracy of the device as follows:

The study found that the OCT device analysis identified the differences between normal and cancerous tissue with 92 percent sensitivity and 92 percent specificity. They also found that the way that OCT spotted cancer in the removed tissue was closely correlated with the results from the postoperative pathology reports, which often came days later.

It also quotes the study author who says:

“For the first time, this study demonstrates the use of OCT for imaging tumor margins within the tumor cavity, in the patient, during surgery,” Boppart said. “It is likely better to check to see if any residual tumor cells might be left behind, rather than checking the tissue mass that was taken out. Then, the surgeon can intervene immediately.”

We’re inclined to give the benefit of the doubt given the story’s good-faith attempt to use some numbers to describe the device’s accuracy. However, we think the study itself had many details, not communicated in the release, that would have added to the release’s credibility, understandability, and potential impact. It would have been very useful to know more about how many of the 35 women participating in the study had mastectomies, for example, how many had invasive cancers, in situ cancers, or ductal cancers; and how large a range the tumors covered.

For the sake of background, we’d add that breast cancer surgeons used to go after wider margins (i.e. more healthy tissue at the edge of the removed tumor) than they do today. There is a large body of evidence that demonstrates that wider margins do not translate to better outcomes, and the SSO-ASTRO margin guideline statement is now fairly well accepted, noting that “no ink on tumor” is sufficient in many cases of invasive cancer; of course this may not apply to all cases. As more physicians adopt the 2014 guidelines, the utility of these devices may be called into question.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

The release did make clear that the OCT device was a light-only probe that carried no need for dyes or invasive procedures; it was “swept” across the tissue so that the microscopic tissue structures could be captured on video and analyzed or compared with the gold standard analyses in the path lab. But the release probably should have said whether the use of OCT added to time under anesthesia or was associated with little or no harm at all to patients. In addition, there is the potential for harm in terms of an impact on cosmetic results if tissue is removed based on a positive reading that was found to be a false positive. One of the cases described in the study was a false positive.

Does the news release seem to grasp the quality of the evidence?

Satisfactory

The release did a pretty good job of noting what the study was designed to do, that ongoing clinical studies will be done, and quoting the investigators as saying the study demonstrates specificity and sensitivity, not that it is ready to replace standard practice at this time.

Does the news release commit disease-mongering?

Satisfactory

No mongering here, but instead a quite clear explanation of why assessing margins is important in the surgical treatment of cancer.

Does the news release identify funding sources & disclose conflicts of interest?

Satisfactory

The release discloses financial and commercialization interests of the principal investigator.

Does the news release compare the new approach with existing alternatives?

Satisfactory

The news release goes into some detail about the current methods used by surgeons and pathologists to assess the extent of a tumor and the likely outer border of margins.

We’ll rate this Satisfactory, although there is no discussion of an existing device — the Dune Medical Margin Probe — that uses different technology but is used for the same purpose. The new device is meant to be used in-vivo (on the lumpectomy or mastectomy bed) versus on the tumor specimen removed during surgery.

Does the news release establish the availability of the treatment/test/product/procedure?

Satisfactory

The release says the device “could soon enable reliable, real-time guidance for surgeons,” which may be a bit optimistic, but at least suggests that the device is not available yet. Toward the end of the release it is stated that “The researchers will continue clinical studies with the OCT device, looking at other types of solid-state tumors,” which arguably suggests the same.

Ideally the text would have been more explicit about whether and/or when the device would be commercialized, but we’ll give the benefit of the doubt.

Does the news release establish the true novelty of the approach?

Satisfactory

As noted above, the release could have mentioned a competing device that has already been found able to distinguish pretty well between normal and cancerous tissue, but not in real time with a portable device in the operating room. However, the release does quote one of the researchers who establishes what is new here: “For the first time, this study demonstrates the use of OCT for imaging tumor margins within the tumor cavity, in the patient, during surgery.” We’ll rate this Satisfactory.

Total Score: 8 of 10 Satisfactory

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