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.