CRO Brain

Why is tumor resection sometimes performed while the patient is awake?

If the tumor is near a motor or speech area, the patient must be awake in order to be stimulated to determine the safe limits of resection.

What is the most common benign brain tumor? In which area of the brain does it occur?

Meningiomas grow in the meninges, the layers of dura matter that cover the brain.

Which factors can affect the median survival of GBM patients?

Typically, GBM patients who receive no intervention may live about 12 months. Surgery may add 4-6 months, radiation may add an additional 4-6 months, and temozolomide may add 3 months.

Tumors presenting in the occipital lobe can produce

Visual changes

Dose constraints: (Dose limits provided in the lectures may differ from those that are printed in the text. Your exams will ask for the dose limits specified in the textbook.)

a. Brain: Max <60 Gy; Mean <30 Gy (textbook: whole brain max 50 Gy) b. Brain stem: Max <54 Gy c. Optic nerve: Max <54 Gy d. Cochlea: Mean <45 Gy (try to spare one) e. Retina: Max <36 Gy (textbook: max 45 Gy) f. Lens: <5 Gy (textbook 10 Gy)

Describe the types of MRI images that are used in to diagnose brain tumors.

a. T1: shows fluid as dark and gray matter as slightly lighter, and the white matter as light gray b. T1+C: T1 w/ contrast will light up blood vessels and tumors c. T2: fluid is bright, white matter is dark, and gray matter is light d. T2 FLAIR: the fluid signal is subtracted from the image, so fluid appears black-for visualizing edema

Describe the most common class of primary brain tumors.

A glioma is a tumor that begins in the brain or spine and is composed of glial cells, a type of brain tissue support cell, including astrocytes, oligodendrocytes, and ependymal cells. These cells do not include neurons. Glial cells are found in both the peripheral nervous system (outside the brain and spine) and the central nervous system. Gliomas account for 42% of all primary brain tumors and 77% of malignant brain tumors.

What is the difference between a primary brain tumor and a metastatic brain tumor?

A primary brain tumor arises independently in the brain and is not part of a disease process elsewhere in the body. A metastatic brain tumor originates in other tissue and has spread to the brain.

What are two common imaging tools used to visualize/diagnose brain tumors? What makes CT an imperfect imaging tool?

CT and MRI are commonly used to visualize brain tumors, but CT cannot show bleeding, edema, or the true extent of the tumor. MRI is preferred.

Grade 2 low-grade gliomas are resected. What is the rationale for radiation therapy with these patients?

EBRT could improve progression free survival if done right away and will improve seizure control. However, survival is not affected by immediate EBRT. Radiation also affects cognitive function.

What kind of margin does the boost PTV receive?

GTV + 0.5cm

What is the most common astrocytic neoplasm, and what are its grade and peak decades of incidence?

Glioblastoma is a Grade 4 malignant tumor that typically occurs in patients from ages 45-70.

What are the Rx's for Grades 2-4?

Grade 2: CTV = GTV + 1cm; PTV = 45 Gy; Boost = 50.4-54 Gy Grade 3: CTV = GTV + 1.5cm PTV = 50 Gy; Boost = 57 Gy Grade 4: CTV = GTV + 2cm; PTV = 50 GY; Boost = 60 Gy

How does the World Health Organization (WHO) grade gliomas? What are the characteristics, treatment options, and overall survival times for each grade?

Grading is based on both cell type and microscopic appearance. Grade 1: Pilocytic astrocytomas generally have very good outcomes with surgery. Slow growing and have a generally normal appearance microscopically. Grade 2: This is a low grade glioma that is slow growing and looks slightly abnormal microscopically. Can spread into nearby tissue and recur as a higher grade tumor. Treated with surgery, and possibly with either radiation and/or chemo. Median survival is about 7 years. Grade 3: Actively growing and spreading into normal tissue. Also tend to recur, often as grade 4, and look anaplastic (poor cellular differentiation). Includes anaplastic astrocytoma. Treated with surgery, radiation, and possibly chemo. Median survival is about 3 years. Grade 4: Highly malignant with poor outcomes. Reproduce rapidly, look abnormal (anaplastic), and form new blood vessels for rapid growth. Contain a center of necrotic cells. Glioblastoma multiforme (GBM) is the most common example. Treated with surgery, radiation, and chemo. Median survival is about 1-2 years.

What are the common symptoms of a brain tumor? Why are they so diverse?

Headache, seizures, visual changes, personality changes, weakness, tingling, numbness. Symptoms and severity will depend on where in the brain the tumor presents.

Tumors that present in the frontal lobe can produce possible

Personality and/or mood changes

Which chemo drug may be given to patients with Grades 2-4 brain lesions to improve overall survival?

Temozolomide

Tumors presenting in the motor cortex can produce symptoms

That manifest in the limbs