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Palliative radiation treatment of cancer in the colon and rectum

Medical editor Marianne Grønlie Guren MD

Oslo University Hospital


Palliative radiation treatment is often given with larger radiation fractions, and over shorter periods, such as two weeks or it may be given in one single fraction in one day. Radiation treatment may be administrated for relief and prevention of symptoms from a tumor.



  • Primary tumors in the rectum, not relevant for surgery
  • Bone metastases
  • Brain metastases
  • Pelvic wall metastases


Relief or prevention of symtoms, such as pain.


Target Volume


Definitions of target volume according to ICRU
(International Commission on Radiation Units and Measurements)
GTV (Gross Tumor Volume) Palpable or visible/identifiable area of malignant growth.

CTV (Clinical Target Volume)

Tissue volume containing GTV and/or subclinical microscopic malignant disease.

ITV (Internal Target Volume)

Volume containing CTV and inner margin taking into account inner movements and changes in CTV.

PTV (Planning Target Volume) Geometric volume containing ITV with set-up margin taking into account assumed patient movement, variation in patient positioning, and field modeling.




  • CT for dosage planning or the radiation field is set directly by X-ray .
  • If CT is taken, location of the tumor and possible risk areas are drawn in on the images and create a 3-dimensional radiation volume.
  • The proposed radiation field is approved by a medical physicist and treating physician. 
  • The field shape is drawn with a marker on the patient's skin.
  • The patient should lie in the supine position during treatment.


The treatment is usually administered as 3 Gy x 10 for metastases to the bone or toward a primary tumor not appropriate for surgery. The treatment is based on individual assessments. In some cases, such as bone metastases, radiation treatment is given in one larger fraction in one day. Or the treatment is administred in smaller fractions during a longer period as 5 weeks, for example tumor in the rectum.

Abdominal wall metastases are treated with electron radiation which penetrates less into the underlying tissue.


The patient is usually followed up at his/hers local hospital after the treatment.

Side effects

The side effects depend on how radiation therapy is administered and the pasients are assessed individually.

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