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Search and destroy

Researchers working to ensure not one cancer cell left behind


By Michelle Osmond

Undergoing surgery to remove a cancerous tumour is not something anyone wants to experience.

But to discover a surgery did not remove all the cancer is another harsh reality that many face.

Members of Dr. Hirasawa’s laboratory in the Faculty of Medicine.
Photo: Submitted

Dr. Ken Hirasawa, a professor of immunology in the Faculty of Medicine, and his team are looking at ways to ensure that the success rate for destroying cancer cells during surgery is 100 per cent.

Distinguishing cells

Chantel Rice is a graduate student in Dr. Hirasawa’s lab. Ms. Rice says that, during cancer removal surgery, it may be hard to locate and remove all of the cancer.

“Even though we might be able to see a tumour in the body during surgery, there is no way to know for certain if all the cancer is removed. That’s because it’s hard to determine whether the tissue surrounding the tumour is cancerous or non-cancerous.”

The researchers hope their work will lead to better detection of those cells using something called protoporphyrin IX (PpIX): a glow-in-the-dark molecule that only develops in cancer cells.

Cancer cells with high levels of PpIX can be destroyed with light, making it a valuable tool to eradicate any remaining cancer cells post-surgery.

Building on findings

Previous research by the team found that inhibiting one of the many pathways, or the molecule interactions that lead to change in cancer cells that help them to grow, causes more PPIX accumulation.

The more PPIX accumulates, the more cells die and the more they glow under certain light conditions during surgery, enabling them to be destroyed by photodynamic therapy.

“If it works, we can better detect, and remove, cancer.” — Chantel Rice

And now, thanks to a large grant from the Canadian Cancer Society, they are taking that research to the next level.

“What we now need to do is to determine if the same thing will occur in cell lines as well as animal models when we combine this higher fluorescence detection method with surgery,” said Ms. Rice. “If it works, we can better detect, and remove, cancer.”

In order to test this, they will inject a naturally occurring photosensitizer into an area of the body where cancer is found. Once it enters the cancer cells, it will change into PPIX. But it will only accumulate in cancer cells — not in non-cancer cells.

Once that occurs, a particular type of light allows them to see it glow in the body.

Surgery and fluorescence detection

In the future, the team will work to increase this glowing property to improve its effectiveness in detection.

If the researchers are successful, their combined strategy of surgery and the fluorescence detection could directly improve the effectiveness of cancer surgery.

“We are hoping this combination strategy can eliminate all the cancer during one surgery and not leave any cancer behind,” said Ms. Rice.

Dr. Hirasawa was awarded an Innovation to Impact grant for $450,000 over three years from the Canadian Cancer Society for the project.

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