‘Dye Hard with a Vengeance’ is Battle Cry in Mesothelioma War

When you have mesothelioma surgery, the doctor wielding the knife can never really be sure that of finding all of the cancer.

That’s because mesothelioma has a way of blending in with healthy tissues along the edges of the tumor.  As a result, tissues the surgeon believes are healthy and avoids cutting out may be in fact mesothelioma.

But if the surgeon even only leaves behind a few of those cancerous tissues, the mesothelioma will later roar back with a vengeance.

Researchers at the University of Pennsylvania last month announced that they have developed a new technique to pull the mask off mesothelioma and make all of the cancer tissue stand out like a sore thumb.

More accurately, it makes the tissue stand out like a flashing neon sign on a darkened street late at night.

The technique causes mesothelioma to glow bright green. This makes it a cinch for the surgeon to nail the whole thing.

The technique is known as near-infrared imaging. It involves injecting the tumor with a special, FDA-approved dye — indocyanine green — and then bathing it in infrared light while the surgeon operates.

Vastly more of the injected indocyanine green finds its way inside mesothelioma tissues than gets inside healthy ones. As a result, only the mesothelioma tissues glow when the infrared light is turned on.

The reason the dye has no trouble getting inside the mesothelioma tissues is that tumor blood vessels have holes in them. Healthy tissue blood vessels don’t. The holes let the dye pour in.

Aims to Thwart Mesothelioma Recurrence

The University of Pennsylvania researchers wrote about this new technique in a recent edition of the online journal PLOS ONE.

They note that as many as half of all mesothelioma patients suffer a local recurrence of the cancer – meaning, it later comes back in the same place as before.

The researchers say a local recurrence is a sure indicator that not all of the mesothelioma was removed during surgery.

Surgeons operated at a disadvantage until this strategy of making mesothelioma glow came along.

Previously, to find where the mesothelioma tissues ended and healthy ones began, surgeons had to look hard and feel around carefully.

“Surgeons have had two things that tell where a cancer is during surgery: their eyes and their hands,” says David Holt, first author on the study and professor of surgery in the university’s School of Veterinary Medicine. “This technique is offering surgeons another tool.”

Tested in Mesothelioma Victims

Since the researchers weren’t positive this new approach would work, they started by testing it in mice.

The researchers were excited when it turned out that painting mesothelioma bright green enabled them to easily tell cancerous from noncancerous tissues in the mice.

But they weren’t quite ready to begin testing in people.

The intermediary step was to try it out in pet dogs that had been brought to the university’s Ryan Veterinary Hospital for treatment of naturally occurring lung cancer.

Again success. The researchers then found five people with the cancer in their lungs or chest. The five were admitted to the Hospital of the University of Pennsylvania for surgery at various times.

Before surgery, each was injected with the dye. The infrared light was shined and the surgeons had at it.

The researchers reported that all of the tumors strongly fluoresced under the light. This gave them the confirmation they were looking for that the technique was suitable for use against mesothelioma in humans.

However, they did find one shortcoming. Healthy but inflamed tissues like the dye as much as the mesothelioma tissues do.

It happens that inflamed tissues are not infrequently found in the vicinity of tumors. Consequently, it proved difficult or impossible to distinguish mesothelioma from healthy but inflamed tissue.

The researchers say they are trying to solve this problem by finding a dye absorbed by only mesothelioma tissues and not healthy cells, inflamed or otherwise.