Prostate Cancer – External Beam Radiation Therapy

Radiation therapy consists of using very high energy x-rays. They are delivered by an external beam from a machine or actually implanted in the prostate to kill cancer cells. This treatment can also be used to treat men whose cancer tumors have advanced into the pelvis and cant be removed with surgery if they have no indication of lymph node invasion. Radiation therapy can also reduce tumors and relieve pain for men who have advanced disease.

External beam radiation therapy treatments are usually conducted 5 days a week for up to 6 or 7 weeks. The treatments are painless with each session lasting just a few minutes. Sometimes, if the tumor is extremely large, hormonal therapy may begin during the radiation therapy and can continue for several years.

Hormonal therapy prevents cancer cells from receiving the hormones that feed their growth. In prostate cancer, male hormones are blocked with hormonal drugs or by surgically removing the testicles.

The prime target of the external beam radiation is the prostate gland itself as well as irradiating the seminal vesicles as they are a common area of cancer spread. It was once believed that irradiating the lymph nodes in the pelvis was necessary, but the long term benefits have proven that this only applies to certain situations.
Since a radiation beam is passed through normal tissue to reach the prostate, there is the risk of killing healthy cells. Diarrhea is a side affect when radiation is applied to the rectum but diarrhea, in addition to fatigue caused by the radiation, will usually disappear when treatment is completed.

One of the long term affects of radiation is proctitus. This presents as inflammation of the rectum, bleeding, bowel problems such as diarrhea and cystitis which is an inflammation of the bladder. This usually leads to problems with urination. Radiation therapy also results in impotency for 40 to 50% of men treated.

Some of these side effects may be minimized by using higher energy radiation beams that can be more precise in targeting the affected area. Coupled with computer technology, treatments are tailored to exactly match the anatomy of the man being treated. This type of state of the art equipment is not always readily available.