The stroma and its role in pancreatic cancer

Have you heard of the stroma?

It’s one reason why pancreatic cancer is so challenging to treat

BY AMBER SMITH

The framework supporting the pancreas (or any internal organ) is called the stroma. It’s comprised of connective tissue that helps to protect the organ and to hold it in place.

When cancer develops in the pancreas, that stroma is an obstruction. It shields the cancer from treatment attempts and allows it to spread through the body.

“A lot of work is being done to look at how we can break down that stroma,” says Thomas VanderMeer, MD, a pancreatic surgeon and interim director of the Upstate Cancer Center.

He explains that the stroma’s extracellular matrix (*) tends to be thick, generating lots of scar tissue. “Those thick scar lines prevent the infiltration of chemotherapy into the tumor,” he says.

At the same time, the cancer prompts extra blood vessels to develop. “That gives the cancer a route out of the primary site in the pancreas and into the bloodstream, to spread to other organs.”

Among the cells that surround the tumor are cancer-associated fibroblasts, some of which encourage tumor growth, and some of which secrete a protein that essentially helps block the body’s immune system surveillance. Lymphocytes, which would otherwise fight off infections and eliminate diseased cells, cannot gain access to pancreatic cancer cells.

“This is really a big area of investigation and success in a lot of other cancers,” VanderMeer says of immunotherapeutic strategies. “It hasn’t been as effective in pancreatic cancer because there’s this barrier to the body’s own immune cells to get in and to attack the pancreatic cancer.’

He says researchers continue to look for ways around the stroma, to improve the treatment of patients with pancreatic cancer. “If we can, for example, get the protein around the tumor to allow the chemotherapy to enter, then chemotherapy can be much more effective.”

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(*) The extracellular matrix is a large network of proteins and other molecules that surround, support, and give structure to cells and tissues in the body. It helps cells attach to, and communicate with, nearby cells, and plays an important role in cell growth, cell movement and other cell functions. – National Cancer Institute