Types of Pediatric Brain Tumors
There are many types of pediatric brain tumors, but the most common include:
- Medulloblastoma or PNET (primitive neuroectodermal tumor)
- Choroid plexus tumors
- Pineal region tumors
Medulloblastoma or PNET (primitive neuroectodermal tumor)
Medulloblastoma or PNET (primitive neuroectodermal tumor) is the most common tumor of childhood. It has a potential for dissemination throughout the nervous system. While its pathogenesis is uncertain, significant advances in its diagnosis and treatment have been made in the last 25 years. The five-year progression-free survival has improved from less than 20 percent to greater than 70 percent.
Our team is performing ongoing studies to reduce the treatment-induced problems while improving survival rates.
Ependymoma is the third most common brain tumor of childhood. In children, 90 percent of these tumors are located within the intracranial compartment, while the remainder exist within the spinal canal. About half of pediatric ependymomas occur in children younger than 5 years.
Surgery is the primary form of treatment. The single most important factor in the prognosis for this tumor appears to be the degree or extent of surgical resection. Radiation is often needed to improve survival.
Unfortunately, high doses of radiation are not possible due to the serious consequences in young children on the developing brain. Advanced techniques to minimize the effect of radiation on critical parts of the brain while treating the tumor are offered through our specialized team. Results from clinical trials on the use of chemotherapy for infants with ependymomas have offered little promise, but more studies and investigation are needed.
Craniopharyngiomas are considered benign tumors, but they may have a very malignant or difficult clinical course. The location is intimately associated with the visual pathways, hypothalamus, and pituitary gland, and the limbic system, which predisposes patients to have significant problems with visual, endocrine, and cognitive and psychosocial function, both at the time of presentation and as a result of treatment.
These sequelae can be devastating. They can interfere with education, limit independence, and negatively affect the quality of life.
While open surgery has been the mainstay of treatment for many of these tumors and often offers curative resection, it is not without the risks noted above. Radiation, intratumoral therapy, and minimally invasive surgery have also shown success.
At UT Southwestern, we employ a multidisciplinary approach to tailor the treatment to each individual patient using various surgical treatments, irradiation techniques, and intracystic therapies to achieve cure while maintaining a good quality of life.
Choroid Plexus Tumors
Choroid plexus tumors are relatively rare in children. They arise from the neuroepithelial lining of the choroid plexus (tissue responsible for production of cerebrospinal fluid) within the ventricles or cavities in the brain. These tumors represent a wide spectrum of properties ranging from very well-demarcated benign tumors to highly aggressive and infiltrating carcinomas. They may reach a very large size and are often associated with hydrocephalus at the time of diagnosis.
The benign variants, in spite of their large size, have an excellent prognosis in the microsurgical era and are potentially curable with complete resection. From the perspective of the surgeon, they are challenging lesions because they possess an impressive vascular supply often buried deep within the tumor mass or opposite the surgeon’s trajectory.
This complex anatomy of the tumor, because of the location and blood supply, often requires multimodal therapy to achieve complete excision with minimal morbidity. We may use endovascular (minimally invasive) techniques to identify and reduce the blood flow to these tumors and may make surgical resection safer. Our multidisciplinary team of advanced pediatric neurologic experts includes interventional radiologists and neurosurgeons who primarily treat complex cerebrovascular disorders in children, in combination with our pediatric neurosurgeons.
The prognosis with those children who undergo surgical excision of choroid plexus carcinomas (malignant), once thought to be dismal, has clearly improved with aggressive surgical treatment followed by comprehensive adjuvant therapy (treatment that lowers the risk of the cancer returning) such as that provided by our experts.
Pineal Region Tumors
(Including germ cell tumors, germinomas, non-germinomatous germ cell tumors, embryonal cell tumor, yolk sac tumors, teratomas (immature vs. mature), pinealoblastomas, and pineaocytoma.)
Pineal region tumors represent a rare and challenging problem to pediatric specialists. The location deep within the brain surrounded by critical blood vessels and the top of the brainstem present a surgical challenge. The types of tumors and their response to different treatments is highly variable. And the presentations with hydrocephalus or varying degrees of brainstem dysfunction may impact treatment.
In the early part of the last century, surgery within this particular region of the brain carried a poor outcome with operative mortality approaching more than 90 percent. It became standard of care to abandon aggressive surgical resection in favor of spinal fluid shunting followed by empiric radiotherapy. Attempts at surgical resection were undertaken only if there was no response to radiation. While this algorithm of CSF diversion, radiation, and observation was sometimes successful, patients with benign tumors were exposed to unnecessary and ineffective radiation.
Clinicians began to use lower doses of radiation to see if there was any response in tumor size before a full course of radiation was instituted. In spite of the lower doses of radiation, significant morbidity to the developing brain in children remained with this strategy.
With the advent and improvement of microsurgical, stereotactic, and endoscopic procedures, all available through our multidisciplinary team, the need for empiric radiation or shunting has been obviated at UTSW. Therapeutic decision making is based on the type of tumor rather than its response to a trial of radiation. Lifelong follow-up of children with these tumors is required. There is a unique role for surgery, chemotherapy, radiotherapy, and radiosurgery for these tumors. It has been the therapeutic and diagnostic advances in all disciplines within our multidisciplinary team that have improved the overall prognosis for children with these tumors.