When removing a malignant tumor, a surgeon can’t see a single cancer cell left behind with the naked eye — or even 10,000 cancer cells. That’s a microscopic amount, which is why excised tumors currently get sent to pathologists. They can look at a few small sections of an excised tumor under the microscope and get an idea of whether the cancer was removed in its entirety. But what if a method was developed that allowed cancer surgeons to see right in the operating room, before the patient was closed back up, whether any cancer cells remained?
Catnip editor-in-chief John Berg, DVM, is involved in cutting-edge research that will allow surgeons to do just that. In an investigation he conducted with fellow scientists at Duke University and MIT, he injected cancer-ridden dogs with a probe prior to their surgeries. The probe is a protein with one or more fluorescent molecules attached to it — it’s delivered intravenously anywhere from several hours to a day or two before the operation.
Once the probe is inside the body, cancer cells — to a much greater degree than normal cells — release enzymes that split the fluorescent molecules from the protein to which they’re attached. That activates them, so when a fluorescent light is shined on the tumor bed — where the surgeon may have left stray cancer cells behind — those molecules fluoresce at a particularly high level, and a special imaging device displays them on a computer monitor. The surgeon, in turn, can see what he missed, potentially even down to a single cancer cell, and remove it. The same exact process would work for cats as well.
To date, a number of different protein-fluorescent probes have been investigated by researchers at different institutions, along with a number of imaging devices. “While it is really exciting, it’s a technology that’s still being researched — but it is on the horizon,” says Dr. Berg. ” Within the next few years, as the technology is perfected, whether the margins are clean or incomplete — as determined by examination of the tumor under a microscope after the surgery — will become less relevant. The cancer surgeon will have better assurance that he ‘got it all’ before the cat even wakes up from the anesthesia.”