“Did you get it all, doctor?” is one of the first questions a cancer patient asks after surgery. Sometimes surgeons have a difficult time answering the question, since missing even a small cluster of nearly indistinguishable cells results in new tumors.
Researchers at the University of Pennsylvania have been turning tumors green! They have taught an old dye some new tricks to assist surgeons in the operating room!
This story begins with the obvious premise: “The best way to cure most cases of cancer is to surgically remove the tumor or tumors.” So, what is the problem? The trouble “is that the surgeon may fail to extract the entire tumor, leading to a local recurrence.”
The new strategy involves an injectable dye which is attracted to cancer cells. With a new technique, researchers at the University of Pennsylvania have established a new tool to help surgeons discover tumor in the patient. Needless to say, if the doctor can see the cancer, he has a better chance of removing it! Here is how it works:
1 A dye is injected into the patient.
2. “When the surgeon shines an infrared light on the cancer, it glows…”
3. Because he can see them so well, the surgeon now has the ability to remove all of the tumors.
David Holt, professor of veterinary surgery at the University of Pennsylvania stated, “Surgeons have had two things that tell where a cancer is during surgery: their eyes and their hands,”
Then, he added the exciting news: “This technique is offering surgeons another tool, to light tumors up during surgery.”
Holt coordinated with Penn’s Perelman School under the leadership of Sunil Singhal, an assistant professor of surgery.
Did you know that between 20 and 50 percent of cancer patients who have surgery for a tumor end up experiencing a recurrence of their cancer? Almost every time, this sad incidence indicates that the surgeon could not see some of the tumor he was trying to remove.
Identifying the margins of a tumor can be difficult to do during a procedure. What do surgeons do? They normally can only do this by looking for the tumor, and feeling its texture with their hands
Holt, Singhal and their team decided to utilize NIR (near infrared)( turned to near-infrared, or NIR, imaging.
1. FDA: They chose to test the only Food and Drug Administration-approved contrast agent for NIR, a dye called indocyanine green.
2. Tumor tissue will fluoresce a bright green under NIR light.
“Since 1958 when ICG was initially FDA approved, it has been used to examine tissue perfusion and clearance studies,”
3. First the team tested the procedure on mice with lung cancer. They discovered that the NIR lit up the tumors. They were actually visible within only 24 days.
4. The second phase of the experiment involved eight client-owned dogs that had naturally developing cases of lung cancer. They received ICG intravenously a day before surgery, then surgeons used NIR.
“It worked,” Holt said, the tumors were fluorescing clearly enough to permit the surgeon to rapidly distinguish the cancer during surgery. “And because it worked in a spontaneous large animal model, we were able to get approval to start trying it in people.”
5. A human clinical trial was then scheduled. Five patients with cancer in their lungs or chest took part in the surgery. In turn, each of them received an injection of ICG prior to surgery. Surgeons used the NIR to find it and cut it out.
“All of the tumors strongly fluoresced under the NIR light, confirming that the technique worked in human cancers.”
For one special patient, participation was key to survival. The doctors thought he had one big tumor. “It turns out, he had diffuse microscopic cancer in multiple areas of the lung.” The imaging, the glowing dye, and the surgeon’s skill plus some radiation killed all the little scattered tumors that would have been unseen, and missed.
Some other research teams have begun investigating NIR for other applications in cancer surgery. This is the first time a group has taken the approach from a mouse model to a large animal model of spontaneous disease and all the way to human clinical trials.
The only flaw in the use of this technique is that the ICG is attracted to inflamed as well as cancerous tissue, but Holt and his team are continuing to work on it.
The Florida Lung, Asthma, and Sleep Specialists (FLASS) are sure they will find the answer to this problem.