5 reasons brain tumors are still treated with radiation therapy

By Jessica Saenz

Radiation has been used to treat cancer since the beginning of the 20th century. Today, radiation therapy continues to be one of the most common and effective treatments for malignant and benign brain tumors. But how it's delivered — and the technology used to deliver it — continues to evolve and improve.

Jennifer Peterson, M.D., a radiation oncologist at Mayo Clinic, discusses what modern radiation therapy for brain tumors looks like and explains why it's still a practical option for patients.

1. It's precise.

Precise radiation delivery to the tumor is critical to avoid damaging surrounding tissues and organs and to successfully destroy the cancer and prevent recurrence.

Dr. Peterson says today’s radiation therapy techniques are more precise and effective. This means patients tolerate the treatment better with fewer side effects. "When we're designing a radiation plan, we outline areas we want to treat and areas we want to avoid. Then we can design a radiation plan to precisely target or avoid those specific areas," she says. "The accuracy with which we can deliver the treatment is usually within millimeters. That limits the excess exposure of healthy tissues to radiation."

Your cancer care team will use advanced imaging like CT scans to guide radiation delivery. "We have imaging that allows us to accurately position patients for the treatment," says Dr. Peterson. "We've also developed adaptive radiation planning, which allows us to alter treatment as needed."

2. It can be tailored to you.

Radiation therapy is not one-size-fits-all. The volume, dose, type and length or frequency of radiation are tailored to your treatment plan. And your treatment plan is tailored to your brain tumor’s size, location and type.

"Every patient and every tumor is different, and a lot of thought and consideration is required to determine the best approach for treating each patient," says Dr. Peterson. "The majority of my brain tumor patients receive one of two types of radiation: external beam radiation, where we design a focused radiation plan to treat the tumor over the course of several weeks, or radiosurgery, where we give a high dose of radiation with a conformal radiation plan in 1–5 treatments."

Stereotactic radiosurgery uses 3D imaging to target high doses of radiation to the affected area with minimal effect on surrounding healthy tissue. It can be delivered via Gamma Knife, linear accelerator (LINAC) and proton beam technology and used in small malignant and benign tumors.

"In benign tumors, radiosurgery is a precise and accurate way to deliver the treatment so there's little exposure to surrounding healthy tissues," says Dr. Peterson. "For malignant tumors, particularly brain metastases, I can use radiosurgery to target each tumor individually instead of using a more comprehensive treatment like whole-brain radiation where you're treating the entire brain with radiation."

Radiation therapy can also shrink cancers before other treatments or ensure that leftover cancer cells are destroyed after treatment. Radiation therapy may also be used to relieve symptoms caused by advanced cancer.

3. It's safer than ever.

Modern radiation therapy techniques have improved in effectiveness and safety. And radiation oncologists are discovering better ways to limit exposure and reduce the risk of secondary cancers from radiation. Still, Dr. Peterson says she often hears concerns from patients regarding the risk of secondary cancers. "A common misconception when patients hear the word radiation is that radiation will cause cancer. While that is possible, the risk of developing a second cancer from radiation is extremely low," she says.

Technology that allows for focused radiation helps reduce the risk of secondary cancers.

When secondary cancer occurs due to radiation therapy, it most often develops years after radiation exposure. However, the risk of developing secondary cancer decreases with time, according to the American Cancer Society. "It's a long-term risk — something that could happen decades down the road — but the ability of the radiation to treat the current tumor or the current problem far exceeds that risk," says Dr. Peterson.

Another misconception Dr. Peterson hears is that radiation therapy can pose a risk to people around you. "It passes right through the body. Patients do not leave their treatments radioactive, and they won't expose family members or other partners to radiation by receiving this type of treatment," she says.

4. Side effects can be minimized or treated.

Dr. Peterson says patients are often concerned about the side effects of radiation therapy, particularly when it comes to fatigue. "The side effects from radiation depend on where in the body we are delivering treatment, but in patients with brain tumors, radiation is well tolerated," she says. "As side effects come up, we can work through them, but in general, most patients can continue their regular activities throughout treatment."

A newer approach to radiation therapy, hypofractionated stereotactic radiotherapy, delivers high doses of radiation over a shortened treatment schedule, which can result in fewer side effects. Dr. Peterson says this can be beneficial to patients with brain tumors. "We know normal structures around the brain can tolerate a certain amount of radiation, especially when you give a high dose. But if we spread that dose out over five days, the tolerance is a bit better, so I can give a higher effective radiation dose with better tolerance over the five days compared to one."

5. It's still evolving.

Radiation therapy continues to evolve through research conducted by Mayo Clinic and others. "I've seen many advances in radiation during my career. Many of them have to do with the technology and our ability to target the tumor more precisely," says Dr. Peterson. She says imaging has also improved to help guide more accurate radiation treatment for patients.

"It's been exciting to watch the world of brain tumors evolve over my career," says Dr. Peterson. "There are patients I treated early in my career who have lived years after treatment, and now their disease is more of a chronic disease that we manage instead of a life-threatening problem. I'm excited about the innovation in our radiation oncology department. I think the opportunity here will be endless."

Learn more

Learn more about radiation therapy and brain tumors and find a brain tumor or radiation oncology clinical trial at Mayo Clinic.

Join the Brain Tumor Support Group on Mayo Clinic Connect.

Also, read these articles:

• "Mayo Clinic Minute: Breaking through radiation therapy myths"
• "How gamma knife surgery treats brain tumors"
• "Getting the right treatment for children with brain tumors"