Operating room technology
The pinnacle of cancer surgery would be the ability to view the negative margin in real- time while operating.
In a similar vein, the MasSpec Pen, which uses mass spectrometry (hence the name) to detect cancer cells by their molecular properties, has shown promise in early clinical research. One study published in the journal Science Translational Medicine found an overall accuracy of 96.3%. The device makers believe it could potentially be used to detect cells in thyroid, lung, pancreatic, ovarian, breast, and brain cancer. The company behind the device, Genio Technologies, are still collecting data to validate it, and as of now it is not authorised for clinical use by the FDA.
“Breast has really been ahead of the curve in de-escalating surgery. And one of the bigger issues for breast conservation is getting a negative margin.” Dr Sarah Blair
96.3%
The accuracy of the MasSpec Pen, which uses mass spectrometry to detect cancer cells by their molecular properties.
Science Translational Medicine 46
Pathology techniques In lieu of fancy new technology, a common way to assess the negative margin is to take out a portion of tissue, freeze it, and then send it off to be analysed in the lab by a pathologist. This is known as frozen section analysis, and it’s routinely used for a range of cancers, including breast, skin, head and neck, pancreatic, ovarian, and vulvar. While it’s generally considered effective, it’s not terribly efficient. “It requires multiple people cutting and freezing and cutting and staining tissues all at once. That’s very labour intensive, so many hospitals don’t do it,” says Dr Blair.
The turnaround time can be an issue for surgeons, too, as they have to wait for pathology results while the patient is under anaesthesia. For breast cancer, there’s just one technique
that’s been shown to improve recurrence rates in randomised controlled trials – cavity shaving. This trial was conducted by Dr Chagpar and her colleagues, and it found that cavity shaving – taking
out extra tissue around the tumour – reduced the positive margin rate by half compared to surgeons who only used x-ray to guide them. “The downside of it is that you’re removing more tissue, and so it can affect the cosmetic outcome,” says Dr Blair. However, she notes, the field is getting better at preserving the look of the breasts in general. Cavity shaving and frozen section analysis are currently considered the gold standard for breast cancer, she adds. For hospitals with a cytopathologist handy, imprint cytology is a good option. This takes “touch” imprints of the tissue sample on a glass slide, and then uses a stain that indicates the presence of cancer cells. It can be used for breast cancer, but also for others, including lung, head and neck cancers. “That is a really good way to do it, but it’s not terribly externally generalisable to the common surgeon living out in Podunk, East Kentucky, who doesn’t have an expert cytopathologist, let alone an expert cytopathologist who can spend a lot of time with you in the OR,” says Dr Chagpar.
Looking forward
Could we soon be able to see cancer on a cellular level? What about being able to analyse tissue on the spot, without needing to wait for the lab report? Maybe. Of what’s currently on the horizon, Dr Blair is most excited about fluorescent imaging – a technique that allows surgeons to identify cancerous tissue instantly while operating. Patients are injected with a fluorescent dye that binds to a target on the surface of the cancer cell, and surgeons can shine a hand-held camera device on the tissue to check if it’s illuminated. “There’s three or four companies that I know of that are going through phase one and phase two studies,” says Dr Blair. “I think [fluorescent imaging] could be a game changer, because you could do it while you’re doing the surgery, and then you could potentially take less tissue.” For Dr Chagpar, though, a more burning question is whether margins are even going to matter that much in the future. “We know that even if you do get a clear margin, if you take cavity shaves, 12-14% of the time in those shaves you will find cancer,” she says. If we’re leaving disease behind some of the time anyway, could we just use other, non-surgical therapies for certain cancers instead? Next year, Dr Chagpar hopes that phase II of her cavity shaving trial will help to answer that question, by comparing breast cancer recurrence rates of those who underwent cavity shaving versus those who didn’t. In the meantime, though, there’s plenty in the pipeline to look forward to. “Hopefully,” says Dr Blair, “in three to five years… we’ll all be wearing fluorescent glasses.”
Practical Patient Care /
www.practical-patient-care.com
Roman Zaiets/
Shutterstock.com
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