Imagine your surprise if you needed heart surgery and were told your cardiac surgeon would be using the same technique their predecessors used in the 1940s.
Thankfully, techniques for heart surgery have come a long way in 70 years. The same cannot be said for Mohs surgery — a procedure for removing skin cancer on the face — according to Massachusetts General Hospital dermatologist Victor Neel, MD, PhD.
“Fred Mohs developed the technique 70 years ago, and today we’re still using the same procedure,” says Dr. Neel. “If Dr. Mohs rose from the grave, put on a white coat and went into the Mohs unit, he’d feel right at home because nothing has changed.”
Neel is evaluating a new technology to modernize Mohs surgery. He hopes this device will improve surgeons’ accuracy and ultimately improve patient outcomes while decreasing costs.
The current standard
Patients are referred to a Mohs surgeon, such as Neel, by a dermatologist after their skin biopsy is diagnosed as cancerous.
During the procedure, the surgeon uses their best judgment to identify the boundary between the tumor and the patient’s normal skin (called the margin), marks it with a pen and removes the tissue for analysis.
In the lab, the tissue is processed and then examined by the surgeon under the microscope for the presence or absence of cancer cells at the margin. If there is residual tumor on the margin, the surgeon returns to the patient and removes more skin. The process is repeated until the margins are free of cancer. Typically, Mohs surgeons need multiple rounds to fully remove the tumor.
Although the procedure has a cure rate that approaches 100%, there are problems with the technique.
“It’s impossible to see skin cancer margins with your eyes,” says Neel. “I’ve done 25,000 cases at Mass General, and about 65 to 70% of the time I get it all in the first pass. That’s been my stable success rate for about 10 years and I can’t seem to do better than that. There’s a limitation to what the unaided eye can see.”
Neel also says there is a lot of variability between Mohs surgeons and how much tissue they remove during each stage.
“Some will start out removing too big of an area. They’ve eliminated the tumor in one pass, but they may have created an unnecessarily big wound on the face. Others inadvertently take too little tissue and they must do multiple stages, which is extremely expensive and time-consuming for the patient. It’s not a good use of resources.”
Seeking an improved methodology for Mohs surgery, Neel partnered with Anna Yaroslavsky, PhD, currently at UMASS Lowell and previously from the Mass General Wellman Center for Photomedicine, to work on new techniques for imaging the skin that would provide surgeons with a way to get a more accurate reading of the tumor’s location before the operation begins.
They have created a device that takes pictures of the structure of collagen in the skin to provide clues to the cancer’s whereabouts. Tumor cells secrete enzymes that deform and destroy collagen’s interwoven mesh-like structure (see photo). By visualizing abnormal collagen, Neel and Yaroslavsky can identify the boundary lines that separate tumor from normal skin before making any incisions.
“We’re not actually looking for tumor cells, per se,” explains Neel. “We’re hunting for deformed collagen which will tell us where the tumor begins and ends.”
The technology, called optical polarization imaging (OPI), functions much like a camera. Using polarized lenses, blue light and some computer analysis, the device can instantly image the area in question.
“It’s a very inexpensive and simple, yet elegant technology,” says Neel. “It would allow Mohs surgeons to take a picture of the surgical site in real time and construct a surgical plan based on what they are now able to see.”
Neel emphasizes that they don’t want to replace Mohs surgery with this device. Rather, it would help improve accuracy and reduce the average number of surgical stages per case.
For patients whose initial biopsy may have removed all of the cancerous cells, it could even save them from undergoing surgery altogether.
“We could image the skin and say to the patient, ‘We don’t see any evidence of residual tumor, so let’s watch this for now and reexamine the collagen for changes in two months.’”
The prospect of fewer surgical stages or even no surgery would appeal to both patients and insurance companies who are footing the bill. Neel thinks Mohs surgeons would also be interested given that the device could double or even triple their efficiency.
If all surgeons utilized the same technique, it would decrease inter-operator variability and standardize the field, he says.
Pilot study results and next steps
Neel, Yaroslavsky and their team recently published a paper showing the successful results from their first pilot study, using data from six cases of patients with basal cell carcinoma (the most common type of skin cancer) to demonstrate proof of concept. In all six cases, the OPI technology accurately predicted the tumor’s boundaries by identifying structural collagen changes.
They’re in the process of submitting a follow-up paper detailing 60 cases with similar results, and next would like to conduct a multicenter trial to prove that other Mohs surgeons can replicate these results.
Before they can expand the trial to other clinical sites, however, they need to miniaturize the bulky prototype, which currently fits onto a cart, into a more portable device that could be handheld. Neel and Yaroslavsky are looking for investors to provide seed money for supporting this venture, with hopes to eventually commercialize the device.
Neel is excited about the potential this technology holds for the future of the field and for Mohs surgeons, including himself.
“I’m looking back at the 25,000 cases I’ve done at Mass General, and I don’t want to do another 25,000 the same way. It’s exciting to see a change on the horizon.”
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