A Ph.D. student at Washington University’s School of Medicine has published the results of a surprising discovery: Calcium carbonate, the common compound found in antacids like Tums, can be used to stop tumor growth in mice.
Here’s how it works: Cancer tumors need an acidic environment to survive. Calcium carbonate, on the other hand, is a base. In a swimming pool, bases can counteract acidity to neutralize the pH of the water and make it safe to swim.
"If you want to kill cancer, you want to find something unique about cancer, that differentiates it from the rest of the body," said Avik Som, the lead researcher for the project. "The pH, was what a lot of people thought was a byproduct."
Instead, Som sees pH as just another thing that makes cancer tissue and healthy tissue different. Because changing the pH of a patient’s body is incredibly dangerous, Som and his team had to find a way to target the tumor, and nothing else.
“This concept of modulating (the pH), and potentially causing tumor inhibition and trying to help cure cancer is novel. Just because we’ve ignored it for a really long time,” Som said.
Researchers put calcium carbonate through a complex engineering process to create nanoparticles, which are so small they can’t be seen by the human eye. These particles were then injected daily into three research mice with solid tumors.
In those cases, the tumors stopped growing and did not expand into healthy tissue — a progression of cancer known as metastasis -- at least as long as the injections continued. A control group made up of mice that did not get injections did experience tumor growth.
Calcium carbonate, or CaCO3, is made up of three elements that the body can easily tolerate: calcium, carbon and oxygen. As a result, it has a very low toxicity, said Dr. Samuel Achilefu, a Washington University radiologist and professor who oversaw the work.
“Our work in this one is significant because we are using what the body can remove, what it can deal with. We are not inducing any kind of immune response that is detrimental to the patient down the line,” Achilefu said.
Recent projects from Achilefu's lab have included the development of “cancer goggles,” which help surgeons discern between cancerous and healthy tissue.
Though the findings about calcium carbonate are confined to mice in a controlled environment, Som says the idea has potential for how we treat cancer. If a specialized form of injections, almost like an insulin pump, can stop the growth of solid tumors, could cancer be treated the same way we treat chronic conditions like diabetes?
“That’s right now, at least, the running hypothesis," Som said.
The article appears in the journal Nanoscale.
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