One of the biggest hurdles that both cancer patients and specialists face is the process of diagnosis. Before any form of cancer treatment can begin, doctors still need to locate the tumor and identify it. Once spotted, one of the widely practiced solutions to prevent the cancer from spreading is surgically removing the tumor. However, such a method has a weakness, as the extraction of a cancerous tumor can be done inaccurately without a proper image of the said tumor. When such a scenario happens, it could mean a local recurrence in the future.
Fortunately, researchers at the University of Pennsylvania have devised a new method that could potentially help surgeons see a patient’s tumor in its entirety, which could increase the chances of a successful outcome.
What is This Approach?
This new strategy relies on a rather specific instrument, which is the injectable dye. Apparently, this injectable dye is able to accumulate more in the tissues of the cancerous tumors than in normal tissues. The result is that when surgeons use an infrared light and aim it at cancerous tumors, the tumors glow, allowing surgeons to remove the entire malignancy much accurately.
David Holt, author of the study and also a professor of surgery in University of Pennsylvania’s School of Veterinary Medicine, said that surgeons only have their eyes and hands to depend on during surgery, but this technique is now an addition to the list, which lights up tumors after injected with dye. Working alongside Holt in the study is Sunil Singhal from Pennsylvania’s Perelman School of Medicine. Singhal is an assistant professor of surgery. Their scientific paper was published in the journal PLOS ONE.
Testing the Intraoperative Near-Infrared Imaging Strategy
Around 20 to 50 percent of cancer patients who have undergone surgical procedures have ended up experiencing their cancers recurring. What this could mean is that the surgeon might have failed to extract all of the cancerous tumor and the surrounding affected tissues from the site. This is because it is extremely difficult to identify the scope of the tumor during the actual removal. How surgeons would go about it is quite simple, and may be a bit inaccurate, as they only look at the tumor using their eyes and feel it with their fingers.
Seeing the need for a more efficient method, Holt and Singhal sought for an alternative. In the process, the two, along with some colleagues, shifted their direction towards near-infrared (NIR) imaging.
They chose a contrast agent that is Food and Drug Administration-approved for the NIR imaging. The dye is called indocyanine green (ICG), which becomes bright green placed under NIR light. What ICG does is it accumulates in the tissues of the tumor more than it does on normal tissues. Why, you ask? This is because the blood vessels of tumors are not as sealed as normal blood vessels. In fact, they have been called “leaky” walls, which allows the cells to grow quickly.
Using an Old Tool to Create a New Technique
ICG has been used for the examination of tissue perfusion and other clearance studies since its FDA approval in 1958. However, Holt and Singhal’s group started welcoming new ideas and experimenting with new strategies that involves using ICG to create a solution to an age-old problem in surgical oncology, which is the prevention of local cancer recurrences. Singhal goes on to say that, “Our work uses an old dye in a new way.”
First Step: Mice
The approach was first tested in mice to find out whether using ICG under NIR could provide the assistance they need to distinguish cancerous tumors from non-cancerous ones. They administered ICG to mice that have a certain type of lung cancer and was able to successfully locate and tell whether the tumors are either cancerous or normal. An even better news is that they were able to see the tumors as early as 15 days after the mice developed cancer. This is astounding because the tumor can only be visible to the human eye 24 days after the development of cancer.
Second Step: Dogs
After a successful run on mice, the researchers then started trying out the technique through eight dogs of different breeds and sizes. They are all client-owned and had developed cancer naturally. They were brought to that are client-owned and , of various breeds and sizes, that had naturally occurring lung cancer and were brought to Penn Vet’s Ryan Veterinary Hospital to receive medical attention and surgery .
The sick dogs were given ICG intravenously a day before the actual surgical procedure. The surgeons then used NIR to see the tumor and attempt to distinguish it from normal tissue. Another good news welcomed Holt as the tumors were bright enough to allow the surgeon to spot the cancer and distinguish it from the rest of the body. What’s even better is that since it worked on dogs, which is a large animal model, they got approval to proceed with human testing.
Human Clinical Trials
The last and final step was to try it on humans. A total of five lung/chest cancer patients participated in the trials, which were performed at the Hospital of the University of Pennsylvania. Each patient was given an injection of ICG before the surgery. During the procedure, the surgeons were able to remove the tumors. These were then analyzed using intraoperative NIR imaging and biopsied.
The results were outstanding, all tumors became clearly visible under NIR light, proving that the technique worked in human cancer tumors.
The surgeon was able to identify tumor from non-tumor by using eyes and hands only, but the fifth patient, needed NIR imaging to reveal diffuse microscopic cancer, something that a CT and PET scan had previously indicated that the tumor was just a solitary mass.
On other words, surgeons would have just labeled the condition as Stage 1 or a local disease, when the cancer could have progressed further. Through the intraoperative NIR imaging and biopsy, they were able to identify the real problem and had the patient undergo chemotherapy. The best news? He survived.
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