What is a diffuse intrinsic pontine glioma?
Diffuse intrinsic pontine gliomas (DIPGs) are highly-aggressive and difficult-to-treat brain tumors found at the base of the brain. They are glial tumors, meaning they arise from the brain's glial tissue — tissue made up of cells that help support and protect the brain's neurons. These tumors are found in an area of the brainstem called the pons, which controls many of the body's most vital functions such as breathing, blood pressure and heart rate.
Approximately 300 children are diagnosed with DIPGs each year, usually between the ages of 5 and 9. Although the prognosis for DIPGs remains very poor but new research, with the help of clinical trials, may provide the key to improved treatment options.
Diffuse Intrinsic Pontine Glioma | Symptoms & Causes
What are the symptoms of diffuse intrinsic pontine gliomas?
The symptoms of diffuse intrinsic pontine glioma (DIPG) usually develop very rapidly prior to diagnosis, reflecting the fast growth of these tumors. Most patients start experiencing symptoms less than three months — and often less than three weeks — before diagnosis. The most common symptoms include:
- rapidly developing problems controlling eye movements, facial expressions, speech, chewing, and swallowing
- weakness in the arms and legs
- problems with walking and coordination
What causes DIPGs?
For a long time, little was understood about DIPGs because clinicians feared they could not be safely biopsied. However, recent and ongoing research at Dana-Farber/Boston Children's Cancer and Blood Disorders Center has led to important discoveries, allowing us to learn more about certain genetic mutations that may cause DIPGs.
Diffuse Intrinsic Pontine Glioma | Diagnosis & Treatments
How is diffuse intrinsic pontine glioma diagnosed?
The first step in treating your child is forming an accurate and complete diagnosis. Diffuse intrinsic pontine glioma (DIPG) is most commonly diagnosed from imaging studies.
Your child’s doctor will perform a complete medical and physical examination. In addition, your child’s physician may order some of the following imaging tests:
How are DIPGs classified?
There are four stages of gliomas, according to how the cells look under a microscope. Ordered from least severe to most severe, they are:
- pilocytic (grade I)
- fibrillary (grade II)
- anaplastic (grade III)
- glioblastoma multiforme (grade IV)
When DIPGs are biopsied, they are usually grade III or grade IV. Occasionally they are grade II, but, because of their location in the brain, they are still considered malignant. These are very aggressive tumors and grow by invading normal brain tissue.
How are DIPGs treated?
Your child’s physician will determine a specific course of treatment based on several factors, including:
- your child's age, overall health, and medical history
- type, location, and size of the tumor
- extent of your child’s disease
- your child's tolerance for specific medications, procedures, or therapies
A number of treatments may be recommended. Some of them help to treat the tumor while others are intended to address complications of the disease or side effects of the treatment. Treatment for DIPG may include radiation therapy.
Radiation is the traditional therapy for newly diagnosed DIPGs, using high-energy rays (radiation) from a specialized machine to damage or kill cancer cells and shrink tumors. Conventional limited-field radiation produces responses in more than 90 percent of children with DIPGs. These responses are short-lived, however, lasting about six to nine months on average. Several trials to increase the dose of radiation therapy have been performed and none have improved survival.
Biologic therapy and chemotherapy, in combination with radiation therapy, are actively being investigated as a treatment for DPG. Several trials evaluating new agents are either underway or have been recently completed. With a biopsy of the tumor at diagnosis, the selection of drugs targeted to your child’s tumor can be determined. Multiple clinical trials have demonstrated that routine chemotherapy does not increase survival rates for this condition.
Complete surgical removal is not an option in the treatment of these tumors, because of their location in the brainstem. Surgery in this part of the brain can cause severe neurological damage and affect the body’s most vital functions and only biopsies can be performed safely.
How we care for DIPGs
Children and adolescents with DIPGs are treated at Dana-Farber/Boston Children's Cancer and Blood Disorders Center through our Glioma Program, one of the world’s largest pediatric glioma treatment programs. Our brain tumor specialists have extensive expertise in treating many types of gliomas, including DIPGs.
Diffuse Intrinsic Pontine Glioma | Research & Innovation
Our areas of research for DIPG
Clinical and basic scientists at both Dana-Farber Cancer Institute and Boston Children’s Hospital are conducting numerous research studies to help clinicians better understand and treat DIPGs, leading a national phase II clinical trial on the genetics of diffuse intrinsic pontine glioma. Using advanced surgical techniques, a surgical biopsy of the tumor was performed on participating patients. Samples were then analyzed at the Broad Institute, Dana-Farber Cancer Institute, and Harvard Medical School as well as with collaborators at McGill University in Montreal, Canada, in order to understand the unique molecular characteristics of each tumor. Dana-Farber/Boston Children’s researchers are using initial findings from that study to develop a follow-up DIPG clinical trial. This new trial will tailor treatments to the specific genetic mutations within each individual patient’s tumor, which hopefully will improve outcomes for children with DIPG.
For many children with rare or hard-to-treat conditions, clinical trials may provide new options.