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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


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



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



Pituitary and hypothalamic dysfunction:



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



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



RT (spinal portion of RT field)


Damage is very common due to the "exit"

dose of the spinal field:



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






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



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

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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