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Follow-up

MRI scanning of the brain will be done every 2-3 months and spinal MRI every 4-6 months for the first two years following surgery. The scans help determine the effectiveness of treatment, and are used to monitor for early evidence of a recurrence. Scans will be done less frequently thereafter, unless specific symptoms develop that might indicate further growth. Your doctor will determine the appropriate schedule.

Children should be carefully evaluated for long-term cognitive problems, and should

receive early aggressive learning support. Neuropsychological testing before treatment can serve as a baseline for follow up evaluations. If learning concerns arise after treatment, these baseline results can be used as a tool for comparison. Children should be carefully evaluated for long-term cognitive problems, and should receive early aggressive learning support. In addition, your doctor may refer you to other specialists, such as an endocrinologist (a physician specially trained in treating growth or hormone imbalances), or an oncologist (a physician trained in treating cancer, particularly with chemotherapy drugs). Rehabilitation and special education programs will play a vital role in returning children to school.

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Side Effects

Despite its impact on increasing survival, the tumor and its treatment can cause significant side effects. Your healthcare team can speak with you about the potential side effects of your/your child’s personalized treatment plan, and help you weigh risks against the benefits. Some of the more common effects are discussed here. In a recent study, about 25% of children undergoing surgery for their tumor developed delayed onset (usually 6 to 24 hours after awakening) loss of speech which was often associated with decreased muscle tone, unsteadiness, emotional lability, and irritability. This syndrome, called “posterior fossa mutism syndrome” or “cerebellar mutism” seems to occur predominantly after surgery in children with medulloblastoma, and has not been clearly related to tumor size or surgical approach. Many of these children recover, but the study noted that some children still have significant neurologic problems – such as abnormal speech and unsteadiness — a year after surgery.

If mutism occurs, a speech pathologist can help outline a temporary communication plan for your child, and help initiate a rehabilitation evaluation. The rehab team can plan a program specialized to your child’s needs and strengths.

Understandably so, parents and adult patients often express concern about the effects of radiation therapy. In the short-term, fatigue, lack of appetite, nausea, sore throat, difficulty swallowing, and hair loss in the path of the radiation beams are the most common acute effects of this treatment. Adults seem to experience these temporary, short term effects to a greater degree than children.

Children appear to experience greater intensity of the long-term effects. Radiation may trigger a decrease in IQ or intellectual ability, accompanied by learning disabilities, attention deficit and memory loss. Most of this research has focused on

children: The younger the child during treatment, the greater the potential subsequent learning challenges. Infants and children less than 3 years of age are particularly vulnerable because the brain is maturing rapidly during this time. For any age group, however, the radiation oncologist will be able to talk with you about what you can expect based on age and the planned dose of radiation.

Radiation can also have long-term effects on the hypothalamus and pituitary, two glands that contribute important hormones for bodily function and growth. Since these glands are directly in the pathway of the radiation beam, their normal function may be disturbed by the treatment. As a consequence, patients can have problems with obesity and hypothyroidism (thyroid deficiencies). They also may experience short stature and scoliosis (curvature of the spine) if the spinal cord is irradiated.

Patients should be evaluated carefully for hypothalamic or pituitary dysfunction and receive replacement therapy. Studies have not shown that children treated with growth hormone replacement are at a higher risk for tumor recurrence. Hearing loss may accompany the use of the drug cisplatin in children. Because this drug has an important role in treating childhood medulloblastoma, scientists are testing “protective” drugs that may be able to defend a child’s hearing mechanisms from cisplatin. This research is ongoing. Hearing may also be affected if radiation beams pass near the ears; an otolaryngologist (an ear, nose and throat doctor) can be of help in diagnosing and treating this effect.

The short-term effects of chemotherapy are similar to those of radiation: Hair loss, nausea, vomiting, fatigue and weakness. But chemotherapy can also lead to reduced blood counts and kidney problems. As patients live longer, there’s the added risk of secondary malignancies, such as leukemia.

Doctors continue to study the long-term effects of both radiation and chemotherapy in hopes of developing new agents and combinations of agents. Discoveries continue to emerge about the molecular mechanisms used by tumor cells to evade the body’s normal growth controls, and the methods by which tumor cells move through the brain or spine.

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Chemotherapy

Chemotherapy uses powerful drugs to kill cancer cells. For children with medulloblastoma, chemotherapy is used to reduce the risk of tumor cells spreading through the spinal fluid. For adults, this benefit is not quite as clear since their tumors tend to regrow in the cerebellum. Because different drugs are effective during different phases of a cell’s life cycle, a combination of drug may be given. The combination increases the likelihood of more tumor cells being destroyed.

Chemotherapy is now a standard part of treatment for children with medulloblastoma. Most children are treated in clinical trials — organized studies that are helping determine which treatments are most effective. Clinical trials also offer a formal way to test new therapies against existing therapies to learn which is better.

In children at average-risk of recurrence, current studies are exploring the use of chemotherapy as a way to reduce the total amount of craniospinal radiation. There are several treatment plans in use, but most focus on a combination of vincristine, cisplatin, lomustine, and/or cyclophosphamide.

For children at high-risk, the drugs vincristine, cisplatin, and cyclophosphamide tend to be the main focus, but others are being tested in clinical trials. Researchers are also looking at the use of chemotherapy as a radiation sensitizer, and at “post-radiation” high-dose chemotherapy accompanied by a stem cell transplant.

For infants under the age of 3, chemotherapy is used to delay or even eliminate radiation therapy. Cyclophosphamide, vincristine, cisplatin, etoposide, carmustine, procarbazine, cytarabine, and/or hydroxyurea may be found in these treatment plans. New drugs are under consideration, but their effectiveness is generally determined in older children prior to use in infants. Some treatment plans use higher doses of chemotherapy, supported by peripheral stem cell rescue, for infants. There is also interest in instilling chemotherapy directly into the cerebrospinal fluid (either “intrathecally” — into the lumbar spine by spinal taps, or “intraventricularly”—

into the ventricular fluids of the brain via an Ommaya reservoir). This is being done in attempts to deliver high doses of therapy to the coating regions of the brain and reduce disease relapse in these areas. In addition, studies are underway evaluating the efficacy and safety of utilizing local radiation therapy (radiation therapy only to the primary tumor site) after chemotherapy in infants whose initial disease was limited to the posterior fossa.

In adults, the usefulness of chemotherapy is less clear. Although large scale studies have not been done, some smaller studies indicate adult tumors may likewise respond to some of the above combinations. But adults seem less able to withstand potential side effects, especially those of the lomustine and cisplatin used in some treatment plans. Studies are exploring the use of cyclophosphamide, ifosfamide, etoposide, or carboplatin in adults, and other studies are exploring pre-radiation chemotherapy plans as alternatives.

Research continues into defining the best use of chemotherapy in average-risk patients; the best tolerated drugs in adults: and new drugs targeted to specific genetic changes found in medulloblastomas. Your doctor will outline a treatment plan based on current studies, the patient’s age, the amount of remaining tumor, and the risk of further disease.

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Radiation

Following surgery, medulloblastoma is usually treated with radiation therapy. It is an important “next-step” because microscopic tumor cells can remain in the surrounding brain tissue even after surgery has successfully removed the entire visible tumor. Since these remaining cells can lead to tumor regrowth, the goal of radiation therapy is to reduce the number of left-over cells. Doctors consider several factors in planning radiation therapy: The age of the patient, the location of the tumor, the amount of remaining tumor, and any tumor spread. Since radiating the brain and central nervous system can be damaging to a developing brain, it is usually delayed in children under age 3. Initial treatment for these young children includes surgery followed by chemotherapy to control the tumor. Radiation may be delivered later, if needed.

For older children and adults, conventional external beam radiation therapy is given to the brain and spine. This area is called the craniospinal axis. This form of radiation is given 5 days a week for 5 to 6 weeks. A “boost” is given to the posterior fossa, the region most at-risk because it housed the original tumor. An additional boost may be given to areas of tumor spread. Age and risk factors determine the total doses of radiation given to each area.

While radiation therapy has proven effective, scientists are still looking for new ways to lower the potential side effects of this treatment. Techniques such as focused radiation, also called stereotactic radiosurgery, aims converged beams of radiation at the tumor. Conformal radiation allows doctors to shape the radiation beams to match the tumor’s contour. The goal of these focused forms of radiation is to spare normal brain tissue while treating tumor. Your radiation oncologist, a doctor specially trained in the use of radiation therapy, can talk with you about the best method of radiating you/your child’s tumor.

Treatment

If the tumor is determined to be a medulloblastoma, current treatment consists of surgically removing as much tumor as possible, followed by craniospinal (brain and spine) radiation and/or chemotherapy. Your doctor will suggest a treatment plan based on factors that indicate the risk of tumor recurrence — either “average-risk”

or “high-risk.” To determine risk, doctors look at the age of the patient; the amount of tumor remaining following surgery; and the amount of metastases, or tumor spread (also called M stage). Children are considered at “average-risk” of recurrence if they are diagnosed after age 3; if all, or nearly all, of the tumor is surgically removed; and if there is no evidence of metastases or tumor spread. All other pediatric medulloblastomas are considered to be at “high-risk” of recurrence. High-risk patients include those under age 3; if more than 1.5 cm (about 1/2 inch) of tumor volume remains following surgery; or if there is any evidence that the disease has spread. For adults, risk is generally determined by the amount of remaining tumor, and the presence or absence of tumor spread. The present staging system for medulloblastoma is of major importance. However, a variety of molecular changes were recently identified in childhood medulloblastoma tumors. Researchers are studying whether these findings will be helpful in determining whether children are of average or high-risk disease, or if the information might help to predict the chances of recurrence or spread. Researchers are also studying ways to obtain this biologic information in real-time (meaning within days after surgery).

M STAGE

“M stage” is a medical way of indicating the degree of metastasis (tumor spread), if any.

M0 means no evidence of metastasis has been found — the tumor appears to be limited to the area in which it grew.

M1 means there are tumor cells in the spinal fluid.

M2 means the tumor has spread within the brain.

M3 means the tumor has spread into the spine.

M4 means tumor spread away from the brain or spine (for example, in the rare situation in which the medulloblastoma spread to the chest or bones).

Surgery

Removing as much tumor as possible is the most important step in treating medulloblastoma. The neurosurgeon has three goals for the surgery:

-         To relieve cerebrospinal fluid buildup caused by tumor or swelling;

-         To confirm the diagnosis by obtaining a tissue sample; and

-         To remove as much tumor as possible with minimal neurological damage.

Several studies have shown the best chance for long-term tumor control is when all of the medulloblastoma visible to the neurosurgeon’s eye can be removed safely. Many technologically-advanced surgical tools are now available. MRI scanning combined with computer-aided navigation tools help the neurosurgeon map the exact tumor location before the operation, and track its removal during the procedure. High-powered microscopes provide visual enhancement. Ultrasound and gentle suction devices are used to remove tumor during the actual procedure. These techniques assist the surgeon in navigating around adjacent healthy structures.

While the goal is to eliminate the tumor, some medulloblastomas cannot be removed completely. In one-third of patients, the tumor grows into the brain stem, making total removal difficult because of potential neurological damage. If the tumor is determined to be inoperable, a biopsy may still be done to confirm the diagnosis. Steroids are drugs used before and after surgery to reduce swelling around the tumor.Occasionally, a ventriculostomy (an external drainage device) may be placed to divert excess cerebrospinal fluid from the brain. A permanent shunt, a long catheter-like tube that drains fluid from the brain to the abdomen, is sometimes necessary. In most cases, however, removing the tumor opens the cerebrospinal pathways, which restores both normal fluid flow and pressure. It also eliminates the need for a shunt or drainage device. Within two days following surgery, an MRI will be done to visualize the amount of remaining tumor. (If an MRI scanner is available in the operating room, the scan may be done during surgery.) The amount of “residual” or remaining tumor will be a strong factor in determining further treatment.