Despite decades of research, lung cancer still remains a major concern for public health officials.In 2014, the American Cancer Society estimates that more than 224,000 Americans were diagnosed with this condition, while more than 159,000 succumbed to this disease. In an effort to treat this form of cancer, many people have cancerous tumors surgically removed from their lungs. Thanks to researchers at a prominent academic medical center, surgeons may have less difficulty in identifying and removing such tumors in the future.
Researchers from Penn Medicine believe that a combination of injectable dyes and Near-Infrared Imaging (NIR) could one day be used to spot abnormal tissue growths. Presenting their findings in the journal The Annals of Thoracic Surgery, the research team tested this new approach for finding tumors on a total of 18 individuals. This group ranged in age from 28 to 79, and participated in the study from January to July of 2012. Each of these subjects had been diagnosed with having a single pulmonary nodule, or a small type of growth that forms within the lungs.
The subjects were injected with indocyanine green (ICG), a type of dye that has long been approved for use in humans by the US Food and Drug Administration. When exposed to Near-Infrared Light, ICG dye gives off a green glow. The walls of the blood vessels found in tumors have leaky walls, which allow this substance to accumulate within abnormal growths. Normal tissue walls, in contrast, are hardy enough to repel ICG. Once it passes through the walls of the tumor, the ICG dye then proceeds to attach itself to the tumor’s receptors.
Mice, Dogs and People
Before testing the ICG/NIR combination on human subjects, the researchers first injected the dye to mice and dogs. In both cases, the ICG successfully distinguished cancerous growths from normal tissues. After getting approval for human trials, the authors administered this dye into the subjects a full 24 hours before they went into surgery.
While operating on the participants, the researchers positioned an NIR camera above the persons’ chest, using this technology to check for glowing growths. Of the 18 tumors in the subjects, the camera was able to spot 16 of these tissue growths, giving it a success rate of 91%. Moreover, the NIR camera also uncovered five additional nodules that could not be identified through other means.
These findings were very encouraging to the report’s senior author, Dr. Sunil Singhal, a Perelman School of Medicine assistant professor of surgery. “To our knowledge, NIR imaging has not been used in thoracic surgery to identify pulmonary nodules that have not been diagnosed preoperatively” Singhal stated. “By removing these we were able to prevent a local cancer recurrence and also reduced these patients’ chances of their cancer spreading and developing into metastatic disease.”
This experiment marked the first time that NIR had found undetected lung tumors in human subjects during a surgical operation. Though this technique needs to be further tested and refined before it can be commonly applied to people, the researchers hope that their work will lead to major advances in field of cancer treatment. The authors also hope to eventually use these same tactics against breast and kidney cancer.