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21

NCCN Guidelines for Patients

®

:

Brain Cancer – Gliomas, Version 1.2016

2

Test and treatment overview

Radiation therapy

are lost, it is called a 1p19q co-deletion. PCR

(

p

olymerase

c

hain

r

eaction) and FISH (

f

luorescence

i

n

s

itu

h

ybridization) are tests that can show if

a deletion is present. Test results are used for

diagnosis and treatment planning. Radiation and

chemotherapy appear to treat cancer cells with

1p19q co-deletion better than cells without the

co-deletion.

IDH1 and IDH2 mutations

IDH1 and IDH2 (

i

socitrate

d

e

h

ydrogenase

1

and

2

)

are proteins in cells. Many grade II and III gliomas

have mutations in the genes of these proteins. These

mutations are also found in glioblastomas that began

as grade II or III gliomas.

IHC (

i

mmuno

h

isto

c

hemistry), PCR, or

pyrosequencing are tests for

IDH1

or

IDH2

gene

mutations. Test results can help with diagnosis and

treatment planning. People treated with radiation

or alkylator chemotherapy tend to live longer if the

cancer cells have

IDH1

or

IDH2

gene mutations.

MGMT promotor status

MGMT (

m

ethyl

g

uanine

m

ethy

l

transferase) is

a protein in cells that repairs damaged DNA. It

helps repair DNA that was damaged by alkylator

chemotherapy.

The gene that helps to make MGMT is silenced

in some high-grade gliomas. The

MGMT

gene is

silenced when the part of DNA that turns it on (called

a promotor region) is methylated. Methylated DNA

has added chemicals called methyl groups.

Tests for MGMT promotor methylation are PCR and

pyrosequencing. Test results are used for treatment

planning. Alkylator chemotherapy works better

overall for glioblastoma that has methylated MGMT

promotor regions compared to unmethylated regions.

Radiation therapy

Radiation therapy is used to treat gliomas that can’t

be removed by surgery. It is also used after surgery

to kill any cancer cells that remain in the brain.

Read Parts 3 through 5 to learn when radiation is an

option. What you can expect during radiation therapy

is briefly described next.

Radiation therapy is a cancer treatment that uses

high-energy, highly focused rays. The rays can be

x-rays, photons, or protons. The rays are delivered

to the tumor to damage DNA. This either kills the

cancer cells or stops new cancer cells from being

made.

Radiation can also harm normal cells. Thus, your

radiation oncologist will use methods that limit how

much normal tissue receives radiation. A radiation

oncologist is a doctor who’s an expert in treating

cancer with radiation.

Depending on the type of glioma, radiation will be

delivered to the tumor plus some tissue around it that

may harbor cancer cells. The treated tissue around

the tumor is called the margin. Your radiation plan will

be tailored to you, your tumor, and your brain. You

are not radioactive after receiving radiation therapy.

EBRT (

e

xternal

b

eam

r

adiation

t

herapy) is the

method used to treat gliomas. This method delivers

radiation from outside your body using a large

machine. The radiation passes through your skin

and other tissue to reach the tumor. You will not see,

hear, or feel the radiation.

Simulation

To receive radiation, you must have a planning

(simulation) session. First, you will be guided and

adjusted into the position needed for treatment.

After this, pictures of your head and the tumor will

be taken with an imaging test. Usually, a CT scan is

used.