Radiation therapy for prostate cancer


When used as first treatment option, radiation therapy can be performed using two regimens:

  • normo-fractionated radiotherapy: 38 to 40 sessions, one session per day from Monday to Friday, over 8 weeks
  • hypo-fractionated radiotherapy: 20 sessions, over 4 weeks

For irradiation of the prostate cavity after prostatectomy (i.e. total resection of the prostate), the regime includes 33-35 sessions over 7 weeks.

External radiation therapy for prostate cancer (i.e. as a first treatment option) is classically performed in 38 to 40 radiation sessions over 8 weeks (normo-fractionated scheme). Currently, the hypo-fractionated scheme  (20 sessions over 4 weeks) is increasingly proposed. The number of sessions is chosen by taking into account various parameters, including the patient’s age, urinary function, and the need or not to irradiate lymph nodes.

For irradiation of the prostatic cavity after prostatectomy, the treatment regimen is 33 to 35 sessions over 7 weeks.


In both cases, radiation therapy may be associated with hormone therapy to chemically “castrate” the patient (i.e. to stop testosterone secretion) for potentiating the radiotherapy effects.


Like with any radiotherapy treatment, the first step is to perform a simulation CT scan during which the radiation oncologist delineates the area to be treated (the entire prostate +/- seminal vesicles +/- pelvic lymph nodes). Small tattoo marks are made on the patient at the end of this scan to serve as landmarks during the treatment sessions and to ensure the correct positioning of the patient at each session. Using the images acquired during this exam, the doctor determines precisely the target volumes to be irradiated and the volumes to be protected (rectum, bladder, and small intestine). Prostate radiotherapy is performed using the intensity modulation technique to limit digestive and urinary side effects as much as possible.


In addition, the radiation oncologist gives dietary and lifestyle suggestions. Specifically, doctors recommend to continue a regular physical activity, and also a low-residue diet to limit food residues in the intestine. This reduces the intestinal work and therefore, the risk of diarrhea. This involves reducing the consumption of fibers, vegetables and fruits, in favor of other foods, such as pasta or rice. In addition, it is recommended not to drink alcohol during the radiotherapy treatment, and to drink plenty of water to reduce the bladder side effects.