Radiothérapie

External radiation therapy for prostate cancer

By Dr. Elie Haddad

Oncologist Radiothérapeuthe – HARTMANN Centre

 

Prostate cancer is the most common human cancers over 50 years in France with 70 000 cases and 9000 deaths annually. It often develops slowly and can currently be early diagnosed by a physical examination and a blood test (PSA, prostate specific antigen). The processing means are numerous and effective. They use either surgery or radiotherapy or hormone therapy or ultrasound. The choice of treatment depends on each case: age, results of biopsies, PSA, results of radiological and scintigraphic investigations, as well as the general condition of the patient. The aim is to get the best control of the disease by producing minimal side effects related to treatment.

External radiation therapy is one of the most commonly used means. Both are current techniques conformal radiotherapy and volumetric modulated radiation therapy guided by the intensity image.

External radiation therapy is done with devices called particle accelerators that can be delivered with very high precision and externally (without touching the patient) a dose of X rays of very high energy, able to reach a target located deep preserving healthy organs nearby.

How acts radiation therapy?

Radiation act by breakage of DNA strands of chromosomes, which prevents cells from dividing: at the end of their life cells die without having produced other cells, causing the disappearance of the tumor over time.

Most normal cells are able to repair the breaks caused by radiation and recover a normal life and a division of capacity.

This mode of action explains both the onset of action of X-rays (which is not immediate but takes several weeks to occur), the contemporary side effects of the action of radiation on normal cells, and the usual lack of serious consequences on normal tissues due to repair phenomena.

How to prepare an external radiotherapy treatment?

The radiation therapist doctor reviews the file and determines the volume in which he wishes to deliver the rays and the total dose and fractionation (number of sessions). The rays are emitted from a machine located near the patient; they cross the skin to reach the tumor.

first carried out a tracking of the prostate tissue that is to be irradiated and of the organs to be protected. The tracking is performed in three dimensions through a scanner said centering or simulation, which is performed in the processing position with restraints.

 

Scanner centrage radiotherapie

The doctor proceeded to contouring of the above volumes and decides the dose to be delivered in each volume, and then intervene physicists and dosimetrists to calculate and optimize radiotherapy technique.

How is the treatment processing?

The radiation treatment is conducted in short sessions that are repeated 35-40 times for a total dose of 70 to 80 grays (unit dose). The rhythm is daily, 5 days a week and each session lasts about 10 to 15 minutes; the treatment is performed by skilled manipulators called radiotherapy. In positioning control during treatment are carried out by X-ray scanner or integrated into radiotherapy machine.

What are the side effects of radiation therapy?

Side effects during treatment are related to the irritation of the prostate adjacent organs or the bladder, rectum, urethra and anus.

 

Radiotherapie prostate et rectum

 

This is frequent urination and sometimes compelling, rectal congestion can lead to hemorrhoidal signs of burning on urination and more frequent nocturnal sunrises.

These irritations disappear after the end of treatment but can be minimized by a significant hydration and a suitable diet.

Fatigue may occur after treatment, it depends on several factors

Late side effects that can occur several months after the end of treatment are rare thanks to the precision of the irradiation technique; it comes with proctitis issuance of mucus or blood during stool and cystitis with belly pain and bleeding in the urine. Their frequency is low around 1à3%. erection disorders are delayed and affect 30% of patients.

Advantages of external radiotherapy

This technique avoids the need for surgery and general anesthesia, and the risks related thereto.

A priori, it gives less urinary and sexual complications than surgery.

The patient does not need to be hospitalized.
It is equally effective in terms of local recurrence over periods of 5 to 7 years. However, its efficacy is possibly lower than the surgery on longer delays.

Disadvantages of external radiotherapy

Its adverse effects are related to the impact of radiation on healthy cells. These are temporary or permanent nature and depend in particular dose and location of radiation, the irradiated volumes and the patient’s general condition and its radiosensitivity.

They can be minimized by optimizing the radiation therapy.

major problem in case of failure of this treatment, he will permanently rendered impossible subsequent use prostatectomy, because of local tissue remodeling associated with poor wound healing caused by large doses of radiation that requires effective radiotherapy.

Recommendations

External radiation therapy is recommended as an alternative to other treatments for cancers identified the stages below T3 (T1 or T2) *, localized (confined to the gland) or not, but without remote extension.

For advanced stage T3 cancers, is the solution recommended as an accompaniment to hormone therapy 2 to 3 years, this protocol provides significant gains in survival.

It can also be recommended to reduce the pain caused by the existence of metastases.

Q1: Can not feel the tumor or to detect by imaging. ; T2: confined to the prostate. ; T3: spread out of the prostate capsule. ; T4: spread to surrounding structures (other than the seminal vesicles): rectum, pelvic wall, bladder.

Few bibliograhical elements (French):

http://www.prostate.fr/cancer-de-la-prostate/traitements/

http://curie.fr/fondation/cancer-prostate-radiotherapie-externe

http://urologie-davody.fr/cancer-de-la-prostate/traitements/la-radiotherapie-externe/

http://www.chu-nantes.fr/servlet/com.univ.collaboratif.utils.LectureFichiergw?ID_FICHIER=1366636475432

http://www.e-cancer.fr/Patients-et-proches/Les-cancers/Cancer-de-la-prostate/Radiotherapie-externe

http://www.procure.ca/radiotherapie-externe/

http://www.e-cancer.fr/Patients-et-proches/Les-cancers/Cancer-de-la-prostate/Radiotherapie-externe/Effets-secondaires

http://www.cancer.ca/fr-ca/cancer-information/cancer-type/prostate/treatment/radiation-therapy/

http://www.prostate-paris.fr/?page=50&

http://www.cancer-de-la-prostate.fr/comprendre-cancer-prostate/decision-operer-cancer.html