It is crucial when extracting cancerous tumors to make sure that no small remnants of the malignant mass are left. Surgeons always aim for "clean margins" when performing surgeries on cancer patients.
Having retained cancerous tissues inside the body could increase the likelihood of spreading the disease and local recurrence. The occurrence could lead to reduced survival time.
To ensure the accuracy of surgeries, researchers from the University of Pennsylvania have come up with a technique to assist surgeons in seeing clearly and ensuring that no diseased tissue is left behind.
The team discovered that an injectable dye, which glows under near-infrared light, could illuminate cancerous tissues in the primary tumor and affected lymph nodes.
As part of their study, the researchers performed surgery on dogs to remove mammary tumors at the School of Veterinary Ryan Hospital. Mammary cancer in dogs is similar to breast cancer in women.
Furthermore, the research team assumes that using a different dye more specific to targeted cancer cells could improve consequences for patients considering breast-conserving surgery to treat their ailment.
The findings of the study were published in the journal PLOS ONE on June 17, 2020.
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What is Indocyanine Green Used For?
In the medical field, indocyanine green injection is a medical dye used in tests to determine liver function, cardiac output, and blood flow in the liver. The dye is administered intravenously.
Furthermore, it is also used to make certain parts of the eye more visible during medical procedures such as angiography.
In the recent study, researchers from Perelman School of Medicine, in collaboration with David Holt, a veterinary surgeon and others from the University of Pennsylvania, have also used the same FDA-approved contrast agent, indocyanine green (ICG).
The dye, which glows under near-infrared light, has been used to discern normal from cancerous tissue for several years now in different types of cancer. Scientists believe that ICG builds up in cancer because it leaks out through the fast-growing blood vessels in tumors.
The goal of the current work was to test the approach in pet dogs with mammary tumors as a model for breast-conserving surgery in women. All pet owners provided consent to be part of the study. A day before surgery, dogs were given an injection of ICG.
The surgeries on the canines were either lumpectomies or mastectomies. The procedure went on as they usually would, following standard-of-care protocols and procedures. After this, the surgeons observed the excised tumors under near-infrared light. They also examined the surgical site to look for signs of glowing ICG.
Tumor glow: Prognostic for Problematic Lymph Nodes
The authors of the study found that larger tumors accumulated more dye. Moreover, they were also interested in analyzing the dogs' lymph nodes. According to Holt, they were able to identify both draining lymph nodes and those with metastatic disease.
In the current practice with breast cancer patients, radioisotopes are administered into the breast to identify draining or sentinel lymph nodes. By using a near-infrared imaging agent administered intravenously, the radioactive agent and protective shielding would no longer be necessary.
Holt adds that if the ICG could be administered via injection prior to surgery, the risk of either removing too many lymph nodes or leaving trace fragments could be avoided. Moreover, in their follow-up work, the team aims to continue investigating the efficiency of their dye in human cancer patients.
