New Radiation Therapy Helps Treat Inoperable Pancreatic Cancer

Pancreatic cancer is a serious and often fatal disease, but a September study published in Practical Radiation Oncology explores a new advancement in radiation therapy that may provide a better treatment option for some patients.

Along with his colleagues, Michael Chuong, MD, study author and a board-certified radiation oncologist with the Miami Cancer Institute, studied 35 pancreas cancer patients who received a treatment called stereotactic magnetic resonance guided adaptive radiation therapy (SMART). The clinical trial evaluated patients who were not candidates for pancreas tumor removal surgery, who had already received some chemotherapy upfront, and whose cancer had not yet spread to other parts of the body.

Researchers found that one year after SMART, nearly 90% of patients had their cancer controlled locally and almost 60% of patients were alive, both of which are favorable compared to historical outcomes with lower radiation dose. Even some patients who initially had inoperable pancreatic cancer were ultimately able to undergo successful surgery after receiving SMART.

It's difficult to locate pancreatic cancer in its early stages. Usually, the cancer spreads or increases in size before people experience symptoms.

“Nearly 50% of patients already have stage 4 cancer at the time they are diagnosed," Manisha Palta, MD, associate professor of radiation oncology at Duke School of Medicine and a board-certified radiation oncologist at Duke Cancer Institute, tells Verywell.

“Pancreas cancer is a deadly disease, in part because most patients are not able to safely have surgery,” Chuong tells Verywell. “Only around 15 to 20% of newly-diagnosed pancreas cancer patients can have surgery because for most patients, the tumor is advanced at the time of diagnosis.”

New Treatment Options and Their Advantages

Historically, chemotherapy served as the mainstay of treatment for inoperable pancreatic cancer, Chuong says.

"If patients later do not have disease progression in other organs, then radiation therapy can provide a significant benefit in local control, quality of life, and potentially overall survival,” he says. “Radiation therapy is delivered with millimeter accuracy and precision to the tumor, and can effectively kill pancreas cancer cells at high enough doses. Randomized data have demonstrated that radiation therapy can provide meaningful clinical benefit as opposed to chemotherapy alone for inoperable patients.”

In order to harness the power of radiation, Chuong and his associates utilized a tool called an MR-LINAC, an innovative MRI machine that allows for real-time visualization of the tumor and surrounding organs during radiation treatment.

“While radiation therapy has been used for many years to treat pancreas cancer, the safe dose of radiation that can be given to tumors is typically limited to a moderate range when using standard radiation delivery machines to avoid severe toxicities related to the nearby stomach, small and large intestine, and liver,” Chuong says.

Ideally, doctors would be able to prescribe higher doses to patients with inoperable pancreatic cancers in order to maximize the probability of tumor eradication, he adds, but that isn't always possible.

“There is a significant risk of causing severe or even fatal injury to patients unless technology such as an MR-LINAC is used to ensure that dose to neighboring organs around the pancreas is within an acceptable range," Chuong says.

The MR-LINAC can overcome several key limitations in delivering higher doses to inoperable pancreas cancers, according to Chuong. Unliked standard radiation, the MR-LINAC allows doctors to continuously view inside the patient's body during treatment in order to accurately target specific areas.

"We can see the heart beating, lungs filling, and pancreas tumor moving during respiration from the beginning to end of treatment," he says.

Internal patient anatomy changes daily, which adds another challenge to delivering highly-accurate and precise radiation therapy.

“Organs move when patients breathe. An MR-LINAC can automatically track where the tumor is at any given time," he says. "For example, if the tumor moves out of the designated treatment area as the patient breathes, the machine will pause the treatment until the tumor returns to that correct area, and then automatically resume treating."

Because patients typically receive radiation therapy over the course of several days, the MR-LINAC allows for treatment to be modified daily to account for the body's internal changes. The MR-LINAC ensures the tumor dose is appropriately high, while the does to surrounding organs is low enough, "which has never been possible before in our field," Chuong says.

This new treatment allows for radiation doses to double, which "may have an effect that is similar to surgery,” he says. “We are optimistic that with longer follow-up, we may confirm that ablative doses delivered on an MR-LINAC significantly improve not only local control, but also overall survival. A remarkable number of our patients remain alive several years after their original pancreas cancer diagnosis, despite not undergoing surgery." 

How Advanced Radiation Therapy Could Be Used in the Future

“MR-LINAC is a relatively new technology," Palta says. "There is some experience using this type of technology to treat other cancers, and this technology is now being evaluated to treat tumors in the liver and pancreas."

A larger study called the ViewRay SMART trial is underway at Miami Cancer Institute and other centers around the country. Patients with inoperable pancreatic cancer are currently being enrolled in a Phase 2 clinical study at Miami Cancer Institute.

“The paper describes an interesting area of investigation, and the results that they present are very promising, so I think it is very appropriate that this type of treatment would be evaluated in a larger clinical trial,” Palta says.