Surgeons Make Cancer Cells Glow Bright Green to Reduce Recurrence

Making cancer tumors glow in the dark may sound like 1950s science fiction, but specialists say the luminous invaders could help reduce recurrence.

Thoracic surgeons, who are mostly limited to sight and feel in identifying tumors and their margins, often inadvertently leave behind cancer cells that increase the chance and rate of a cancer returning.

However, doctors in the Perelman School of Medicine at the University of Pennsylvania are injecting lung cancer patients with a dye that makes cancerous tissue glow bright green under near-infrared light (NIF), making tumors more identifiable during surgery and less likely missed by surgeons.

“This has worked well with lung cancer,” University of Pennsylvania surgeon Sunil Singhal, M.D., told Asbestos.com recently. “No doubt, the potential application is there for mesothelioma. This could change the way surgeries are done.”

Although the technique has not been used on human patients with mesothelioma, Singhal believes that moment is approaching.

Testing the Glowing Dye

The experimental technique was first tested in the Pennsylvania School of Veterinary Medicine on 50 mice injected with cancer cells (including mesothelioma), and then eight dogs with lung tumors. Research continued with five humans with cancer in the lungs or elsewhere in the chest, according to the results of the study published in the scientific journal PLOS ONE.

Doctors injected all patients with indocyanine green (ICG), a popular, nontoxic contrast agent approved by the U.S. Food and Drug Administration and used in fluorescence imaging because it glows green under NIF light. Because ICG concentrates more in tumor tissues than in normal ones, it creates an obvious visual differentiation.

ICG has been used for years to examine tissue perfusion and for surgery-clearance studies. Only recently has it been used with the goal of preventing local-recurrence of cancer after surgery.

Results of the Study Were Mixed

Scientists discovered they could distinguish tumors from healthy lung tissue as early as 15 days after the mice acquired cancer. The same tumors were not visible to the human eye until 24 days.

Researchers said the NIR imaging on the dogs “was not particularly superior to the surgeons’ ability to tell apart normal versus cancerous tissue,” the study shows.

The results on the human patients were more significant, although there were limitations.

In four of the five human patients, surgeons easily could see, feel and mark the tumor margins with or without the NIR light; however, the NIR light in the fifth patient revealed glowing sections of diffuse microscopic cancer that extended beyond the tumor margin in an area originally thought as a healthy part of the lung.

But the study’s results show the NIR light was unable to distinguish cancer cells from inflammatory tissue, the report shows.

“There is a lot of work to be done, but this concept is really appealing,” Singhal said.

‘Concept Is Promising’

The Perelman School estimates that 20 to 50 percent of all cancer surgery patients eventually have recurrence, which often comes from microscopic cancer cells left behind.

The diffuse nature of pleural mesothelioma makes it difficult for even the best thoracic surgeon to know that all cancer cells were removed. That problem has sparked intraoperative chemotherapy and photodynamic therapy, both designed to help kill cancer cells remaining after surgery.

This new visualization technique using the glowing green dye should help surgeons better identify all cancer cells, reducing those odds.

“That’s been a fundamental problem with cancer surgery for many years,” Singhal said. “That’s why this is so intriguing. There are a lot of things that need to be worked out, but the concept is promising.”