Effectiveness of External Beam Radiation Treatment for Prostate Cancer

Radiation Therapy for Prostate Cancer

External beam radiation treatment for prostate cancer involves delivery of high-energy beams of X-ray or other types of radiation to the affected area of the prostate gland. The goal of this therapy is to destroy cancer cells with high-power beams of radiation. The patient is made to lie on a table, while an external machine is moved around the body to send radiation to the cancerous tissue. This therapy is usually performed as an outpatient procedure. It is conducted over small sessions of five days a week and continues for a period of six to eight weeks consecutively.

External radiation therapy is one of the common treatment options for prostate cancer, particularly when the cancer is still confined to the prostate or nearby areas. This treatment traditionally involved the use of electron beams, but the latest versions of machines allow for radiation intensity modulation, and also offer 3D-CRT and proton beam therapy. Some advanced medical institutions are also experimenting with neutron beams for more effective results.

How Do Radiation Beams Work?

External beam radiation treatment for prostate cancer is quite effective because the high-intensity beams damage or kill the DNA of the targeted cells. The goal is to let the malignant cell divide itself before it gets a chance to repair the damage. This process kills the cell. Malignant cells have a higher tendency of dividing themselves, which makes it possible to cause their death with precisely aimed radiation beams. Precision is of paramount importance in this treatment so that the surrounding healthy tissue receives minimum radiation exposure.

Three types of external beam radiation treatments are currently used, which include 3D-CRT, IMRT and EBRT. This classification is on the basis of the type of high-energy beams that are used. The aim of these treatments is to induce sub-atomic particles called electrons to produce waves of high-powered photon radiation. In recent years, the use of proton beam therapy instead of electrons is being preferred due to its stronger intensity. External beam radiation therapy is sometimes also known as fractionated therapy because it delivers small doses of radiation over a period of time.

Types of External Beam Radiation for Prostate Cancer

3-D Conformal Radiation Therapy (3D-CRT) is one of the advanced procedures used to deliver radiation to the prostate. It involves the use of a body immobilization device to enhance the precision of the treatment. For the radiation therapist it gets simpler to target radiation on an immobile patient because there is no risk of patient movement. This minimizes damage to the surrounding healthy cells and maximum destruction can be caused to the targeted area. The second treatment option is Proton Beam Radiation Therapy which is quite similar to the procedure of 3D-CRT. The use of proton beams allows for improved precision and results in maximum energy being deposited into the cancerous tissue.

Another treatment version available today is Intensity Modulated Radiation Therapy (IMRT) that goes one step beyond 3D-CRT. In this case the intensity of the external beam is modulated in such a way that smaller beams of radiation are delivered from different positions at small intervals. The number of beams becomes higher, but each beam is thinner and more precise to hit the targeted cells, and spare the healthy cells. IMRT is gradually gaining an increased acceptance as an effective delivery mechanism for radiotherapy for prostate cancer.

References

National Cancer Institute: https://www.cancer.gov/cancertopics/pdq/treatment/prostate/Patient/page4#Keypoint16

Mayo Clinic: https://www.mayoclinic.com/health/prostate-cancer/DS00043/DSECTION=treatments-and-drugs

Prostate Cancer Treatment Guide: https://www.prostate-cancer.com/radiation/treatment-description/radiation-description.html