ConditionCancer
Radiation Necrosis
Radiation necrosis is the death of healthy tissue in an area treated with radiation therapy, usually appearing 6 months to several years after treatment. It is best known in the brain after radiotherapy or stereotactic radiosurgery for brain tumors or metastases, where it causes swelling, headaches, seizures or new neurological symptoms. It can look very similar to tumor regrowth on scans, which makes diagnosis challenging. Many cases need only monitoring; others respond to steroids, bevacizumab, laser ablation or surgery.
Also called: Radiation-induced necrosis, cerebral radiation necrosis, radionecrosis, osteoradionecrosis (in bone)
At a glance
- What it is
- Delayed death of normal tissue caused by radiation therapy.
- Most common site
- The brain, after radiosurgery or radiotherapy; also jawbone, other bones and soft tissues.
- Timing
- Usually 6 months to 3 years after radiation, sometimes later.
- Symptoms
- Headache, seizures, weakness, speech or thinking changes, depending on location; may be none.
- Diagnosis
- Advanced MRI (perfusion, spectroscopy), PET, sometimes biopsy.
- Treatment
- Observation, steroids, bevacizumab, laser interstitial thermal therapy, or surgery.
When to get help
Call 911 or go to the ER
- A seizure, especially a first one or one lasting more than 5 minutes
- Sudden weakness, numbness, speech difficulty, severe headache, confusion or drowsiness after brain radiation: call 911
See a doctor within a day or two
- New or worsening headaches, vomiting, balance problems or personality changes months after brain radiotherapy
- Jaw pain, exposed bone in the mouth, or a non-healing sore after head and neck radiation
Book a routine appointment
- Changes on a follow-up scan without symptoms, to discuss with your oncology team
- Steroid side effects such as high blood sugar, mood changes or weight gain
How radiation necrosis develops
Radiation kills cancer cells by damaging DNA, but nearby healthy tissue also receives some dose. Over months to years, damage to small blood vessels and supporting cells can lead to:
- leaky, thickened blood vessels and poor blood supply
- inflammation and swelling (edema)
- death of tissue in the treated area
The risk rises with higher total doses, larger treated volumes, higher dose per session (as in radiosurgery), repeat irradiation of the same area, and some combined treatments such as immunotherapy or certain targeted drugs.
Where it occurs
- Brain: after stereotactic radiosurgery for brain metastases, radiotherapy for glioma and other brain tumors, or for arteriovenous malformations
- Jaw (osteoradionecrosis): after head and neck cancer radiation, often triggered by tooth extraction
- Other bones: ribs, pelvis, chest wall
- Soft tissues: skin, bladder, bowel and lungs (radiation fibrosis)
Symptoms
Brain radiation necrosis
Symptoms depend on the location and the amount of surrounding swelling:
- headaches
- seizures
- weakness or numbness on one side
- speech or language difficulties
- memory, thinking or personality changes
- balance problems
- nausea and vomiting from raised pressure
Some people have no symptoms and the change is found on a routine scan.
Osteoradionecrosis of the jaw
- jaw pain and swelling
- exposed bone in the mouth
- loose teeth, non-healing sores
- numbness, infection, discharge
Radiation necrosis vs tumor progression
Both can show an enlarging, enhancing area with swelling on standard MRI. Distinguishing them is essential because treatments differ.
| Tool | How it helps |
|---|---|
| Timing | Necrosis often appears 6 to 24 months after radiosurgery; progression can occur anytime |
| Perfusion MRI | Tumor usually shows higher blood volume; necrosis lower |
| MR spectroscopy | Chemical patterns differ between tumor and dead tissue |
| PET scans (FDG or amino acid) | Tumor is usually more metabolically active |
| Serial MRI | Necrosis often stabilizes or shrinks over time |
| Biopsy or surgery | Definitive, but invasive |
Often a mixture of both is present.
Treatment
Observation
Small, symptom-free areas are often monitored with repeat MRI, as many stabilize or improve.
Medicines
- Corticosteroids (dexamethasone) reduce swelling and symptoms; they are tapered as soon as possible because of side effects.
- Bevacizumab, an antibody against VEGF, reduces leaky blood vessels and swelling and can allow steroids to be stopped.
- Anti-seizure medicines when seizures occur.
- Pentoxifylline and vitamin E have been used with limited evidence.
Procedures
- Laser interstitial thermal therapy (LITT): a minimally invasive procedure that heats and destroys the necrotic area through a small hole in the skull.
- Surgical removal for large lesions with significant swelling, or when tumor regrowth cannot be excluded.
- Hyperbaric oxygen therapy: used for osteoradionecrosis of the jaw and some soft tissue injury; evidence for brain necrosis is limited.
Jaw osteoradionecrosis
Good oral hygiene, dental assessment before radiation, antibiotics, removal of dead bone, and medicines such as pentoxifylline, vitamin E and clodronate in some cases.
Outlook
Many cases of brain radiation necrosis are mild and stabilize. Others cause persistent symptoms but often respond to treatment. Prognosis also depends on the underlying cancer.
Frequently asked questions
What is radiation necrosis?
It is the death of normal tissue in an area treated with radiation therapy, occurring months to years after treatment. It most often affects the brain after radiosurgery, causing swelling and sometimes neurological symptoms.
How long after radiation does necrosis occur?
It usually appears between 6 months and 3 years after radiation, most often within the first 2 years, but it can occur later.
How do doctors tell radiation necrosis from tumor regrowth?
They use advanced imaging such as perfusion MRI, MR spectroscopy and PET scans, and follow changes over time. Sometimes a biopsy or surgery is needed for a definite answer, and both can be present together.
Is radiation necrosis treatable?
Yes. Many cases need only monitoring. Steroids, bevacizumab, laser ablation or surgery can treat symptomatic necrosis, and anti-seizure medicines control seizures.
Sources
This guide was written from current patient and clinical guidance, including:
- National Cancer Institute: Radiation therapy side effects
- American Association of Neurological Surgeons: Radiation necrosis
- American Society for Radiation Oncology (ASTRO): Stereotactic radiosurgery for brain metastases guideline
- National Comprehensive Cancer Network (NCCN) Guidelines for Patients: Brain cancer
- American Brain Tumor Association: Radiation necrosis