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Curative radiation treatment of cancer in the colon and rectum


Curative radiation treatment of colon cancer

Radiation treatment for colon cancer is rarely administered and therefore not further described in this procedure.

Curative radiation treatment of rectal cancer

Curative radiation treatment has been used for many years for locally advanced rectal cancer. Due to intermediary radiation sensitivity, radiation treatment alone has not been considered potential curative treatment

Previously, radiation treatment was administered postoperatively in patients at risk of recurrence. Several studies show better effect by giving radiation therapy before surgery, with less side effects. About 30-40% of patients with rectal cancer receive radiation treatment before surgery.

Radiation treatment is usually given in fractions of 2 Gy, totally 50 Gy. The treatment is given on 25 weekdays. 

The effect of radiation treatment is enhanced when combined with chemotherapy (5-FU regimens). Combining radiation therapy with oral capecitabine or FLV intravenously is most common. The effect on the tumor is better and there are few additional side effects (4).

For some patients it may be appropriate to provide radiation treatment over a shorter period, and in larger fractions. 5 Gy is given on 5 weekdays, totally 25 Gy.


Preoperative radiation

  • Preoperative radiation treatment, 2 Gy x 25, with chemotherapy is recommended in patients with T4 tumor or with tumor tissue with distance less than 3 mm from the mesorectum assessed by pelvic MRI. This treatment is also given to patients with lymph node metastases outside the mesorectal fascia.
  • 5 Gy x 5 may be appropriate in elderly patiens or patiens with comorbidity. This treatment is also increasingly used if metastases are found. One may then provide more chemotherapy and radiation therapy.
  • Local recurrence generally requires radiation therapy before surgery. Reradiation should be considered, if the patient previously has received radiation treatment. In some cases the treatment is given divided in two daily doses (hyperfractionated), to protect healthy tissue.

Postoperative radiation

Postoperative radiation can be given when preoperative radiation is not given in cases of:

  • T4 tumor
  • preopertively or peropertively perforation of the tumor or near the tumor 
  • microscopic or macroscopic remaining tumor


The radiation therapy is usually given to reduce the tumor and to enable radical surgery with wide margins. This is shown to be important in preventing local recurrence of the disease and may also contribute to improved survival.


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