Class notes
Washington and Leaver Chapter 35 Radiation Therapy Notes
- Course
- RADT (RAD242)
- Institution
- Wallace State Community College Hanceville
These guided notes will prepare you for a test on this chapter.
[Show more]
Connected book
Book Title:
Author(s):
- Edition:
- ISBN:
- Edition:
Seller
Follow
Content preview
Principles and Practice IIChapter 35:
BRAIN TUMORS:
- CNS cancers are the second most common cancers (20%) in children (after leukemia)
- Remain a leading cause of death, 5-year survival rates have gone from 63% to 75%
- Within the CNS, the brain is the most common site of disease
- Children are more frequently diagnosed with low-grade, infratentorial lesions when
compared with their adult counterparts
- Primitive neuroectodermal tumors (PNET) are also more common in younger ages (such
as medulloblastoma)
- Multidisciplinary approach
Low grade astrocytomas:
(astrocytomas are star shaped glial cells within the CNS)
- Exhibit slow, relentless growth and occur with equal frequency in the cerebrum and
posterior fossa
- Pilocytic low-grade lesions are the most common low-grade lesions in the pediatric group
- Present with nonspecific symptoms for years, headaches, degenerating coordination,
vision issues, and later seizures
- Well circumscribed and solid, often with a cystic component, less surrounding edema or
mass effect is found than with high-grade lesions
- Surgery is the mainstay of treatment
- If discovered in extremely young child with no neurologic defects, no immediate
treatment is required (wait until ages 3-5)
- 50-54 Gy is the typical dose
- 1.5cm for CTV + 0.5cm for PTV
High-grade astrocytomas:
(aka anaplastic astrocytomas and glioblastoma multiforme)
- Highly malignant and aggressive
- High-grade gliomas are typically supratentorial
- Rapidly progressing symptoms such as headaches, lethargy, motor or sensory loss,
seizures, and altered mental status
- Disrupt the BBB, have irregular borders, and contain areas of necrosis and surrounding
edema
- Neurosurgery first, multiple modalities
- Surgery provides immediate symptomatic relief, but residual tumor almost always
remains
, - Surgery goal of a complete resection, surgeon goal of maximum safe resection
compatible with good neurologic outcome
- Radiation treatment fields are large to encompass whole disease
- 3cm PTV, 45Gy-50Gy with boost bringing dose up to 54Gy-60Gy
- Overall, a poor prognosis
- Chemo is useful in infants to delay RT while the brain matures
Optic glioma:
- Low-grade, behave indolently, typically classified as grade 1 astrocytomas
- Visual disturbance is the most common presenting symptom
- Observation may be the initial strategy
- MRI is vital for treatment planning
- Tumors may be bilateral or track along the optic nerves, chiasm, and optic tracts
Ependymoma:
- Arise from cells that line the ventricles and may occur anywhere within the CNS
- Highest prevalence within the posterior fossa, arising from floor or roof of fourth
ventricle
- Presenting symptoms and pre-op imaging often mimic medulloblastoma, resulting from
increased intracranial pressure
- CSF seeding occurs in 5%-10% of all patients, more frequent in patients with
infratentorial and anaplastic ependymomas
- Gross total resection and post-op RT is the standard of care for ependymomas
- Extent of surgical resection is the most important prognostic factor
- CSI if seeding is noted
Medulloblastoma:
- Prototype posterior fossa malignancy and constitutes 20% of childhood brain tumors
- Type of PNET believed to arise from cerebellar stem cells
- Classic appearance is a “small, blue, round” cell that forms pseudorosettes
- Usually arises in the midline of the cerebellum and projects into the fourth ventricle and
brainstem
- 30%-35% of patients present with CSF seeding (mostly from anaplastic
medulloblastoma)
- Presenting symptoms occur within weeks or months, hydrocephalus may result from
decreased CSF flow to the fourth ventricle
- Headaches, morning vomiting, ataxia, cranial nerve abnormalities from invasion of the
brainstem
- MRI of the entire CNS and lumbar puncture to look for CSF seeding
- Maximal tumor resection is vital to good outcomes, posterior occipital craniotomy is used
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller lilyberg13. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $7.99. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
72964 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now