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Medulloblastoma

 

 

Late Effects

Late Effects of Radiation Therapy (RT):

  • Occur 90 days to many years after RT 

Late Effects depend very much on:

  • Age of the child at therapy:
    • The younger the child, the more pronounced the toxicity is likely to be
  • Dose of RT:
    • Higher dose associated with increased toxicity
  • RT treatment field extent:
    • Craniospinal RT more damaging than focal field
  • Concurrent chemotherapy increases toxicity

Medulloblastoma is usually treated with craniospinal RT and children who develop this disease are often between 4 and 6 years old, so as a group they suffer from significant treatment related toxicity. The most devastating late effect of therapy for medulloblastoma is usually neurocognitive delay.

 

Summary of Late Effects after radiation therapy for medulloblastoma:

Therapy Late Toxicity

Craniospinal

RT (cranial portion of RT field) and posterior fossa boost

Lens of eye:

  • Cataracts risk between 5 - 10%
  • Lens of the eye very sensitive to RT

 

Scalp and skin:

  • Sparse growth of scalp hair: Especially affects posterior fossa where "boost" of extra RT is given
  • Increased risk of skin cancers (basal cell carcinoma and melanoma)

 

CNS/supratentorial brain:

Neurocognitive problems:

  • Poor short term memory
  • Difficulty with executive function

 

Depression:

  • Usually related to multiple long-term health problems and neurocognitive dysfunction

 

Pituitary:

Pituitary and hypothalamic dysfunction:

 

Cerebellum:

  • Chronic ataxia can occur as a result of cerebellar atrophy
  • Related to posterior fossa boost

 

Hearing:

Hearing loss Related to:

  • Direct RT related damage to the cochlea
  • Compounded sometimes by previous cisplatin

 

Cerebral vasculature:

Increased risk for cerebrovascular events (strokes):

  • RT effect on cerebral vasculature

 

Second cancers:

Increased risk of second neoplasms:

 

Reduced growth of normal structures:

  • Hypoplasia of occipital region and reduced growth of upper cervical spine related to posterior fossa boost

 

Craniospinal

RT (spinal portion of RT field)

Thyroid:

Damage is very common due to the "exit"

dose of the spinal field:

 

Spine:

Spinal damage from RT effect on spinal growth may result in:

  • Short sitting height (and therefore total height)
  • Scoliosis and kyphosis of spine leading to pain
  • Increased risk of early spinal arthritis and osteoporosis

 

Skin:

 

Gonads:

Infertility:

  • Exit dose from lower end of spinal field damages ovaries or testicles

 

Heart:

Cardiac damage is very rare:

  • Valvular stenosis from exit RT exit dose in young children (rare)

Bone marrow:

Damage to bone marrow reserve:

  • After craniospinal RT, it is very difficult to tolerate further intensive chemotherapy
  • Bone marrow reserve is permanently damaged

 

 

Summary of Late Effects after surgery for medulloblastoma:

Therapy Late Toxicity
Surgical resection of tumor Cerebellar mutism

 

Summary of Late Effects after chemotherapy for medulloblastoma:

Therapy Late Toxicity
Chemotherapy

Cisplatin associated with:

  • High frequency hearing loss
  • With RT this may cause severe hearing impairment

 

Vincristine associated with:

  • Peripheral neuropathy

 

Alkylating agents associated with:

  • Infertility
  • Second malignancies

 

 

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