NCCN Guidelines for Patients
Colon Cancer, Version 1.2017
Radiation therapy uses high-energy, highly focused
rays to treat cancer. The rays damage DNA. This
either kills the cancer cells or stops new cancer cells
from being made.
Radiation therapy is not often used to treat colon
cancer. You may receive radiation therapy as part of
a clinical trial. Otherwise, Parts 4 and 5 explain when
radiation therapy is an option.
Most often, EBRT (
herapy) is the method used to treat colon cancer.
This method delivers radiation from outside your
body using a large machine.
See Figure 13
The radiation passes through your skin and other
tissue to reach the tumor.
A planning session is needed to receive the best
treatment. This session is called simulation. First, you
will be guided and adjusted into the position needed
for treatment. After this, pictures of the cancer sites
will be made with an imaging test.
Using the pictures, your radiation team will plan
treatment. A team consists of doctors, medical
physicists, and technical experts in radiation
planning. They will plan the best dose, number and
shape of radiation beams, and number of treatments.
Conformal techniques are used for colon cancer.
These techniques shape the radiation dose to the
cancer site to spare healthy tissue. However, some
healthy tissue still gets radiated. The radiation dose
is shaped with computer software and hardware
added to the machine. The types of conformal
herapy) delivers, from different
angles, a photon beam that matches the shape
of the tumor. Treatment is completed in about 6
is a form of 3D-CRT that further modifies the
beam’s intensity during treatment. Treatment is
completed in about 6 weeks. IMRT should be
used only for a second treatment with radiation
or for cancer in an uncommon site.
treats cancer with very precise, high-dose
photon beams. Receiving SBRT is much like
other conformal techniques except treatment
is finished in about 5 visits. At this time, SBRT
should only be used to treat colon cancer in the
liver or lungs.
Overview of cancer treatments
External beam radiation therapy
Radiation therapy is often delivered from a
large machine. The rays pass through skin and
travel to the tumor. Healthy tissue is protected
using modern types of treatment.