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.
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.
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.
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.
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.
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.
No mongering here, but instead a quite clear explanation of why assessing margins is important in the surgical treatment of cancer.
The release discloses financial and commercialization interests of the principal investigator.
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.
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.
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.
Pretty careful narrative prose.