External Beam Radiation Therapy

External beam radiation therapy or EBRT involves the use of high powered X-rays, delivered from outside the body. EBRT is often recommended for men with prostate cancer that has spread outside the prostate but remains confined to the immediate area.

This procedure is painless and only takes a few minutes, but needs to be done five days a week, for about seven or eight weeks.

The rays pass through and can damage other tissue on the way to the tumor, causing side effects such as short term bowel or bladder problems, and long term erectile dysfunction. Radiation therapy can also temporarily decrease energy levels and cause loss of appetite.

Imaging studies are done to determine, as precisely as possible, the location of the cancer before treatment.

New techniques are being developed in an attempt to lessen the damage to surrounding tissue. Three-dimensional conformal radiation therapy (3-D CRT) involves beams of radiation aimed from several different directions. The beams overlap at the location of the cancer, providing a higher dose of radiation while exposing the surrounding tissue to lower doses.

Digital imaging and computer software are used to precisely focus the radiation to the shape of the tumor. Researchers are also experimenting with higher doses of radiation to determine how much can be delivered without a significant increase in side effects.

Intensity modulated radiation therapy (IMRT) is an even more precise version of 3-D CRT in which many very small beams are used and the intensity of each can be precisely controlled to ‘bend’ around healthy tissue.

Proton beam radiation therapy uses proton beams, not X-rays. Proton beams deliver radioactive particles to kill the cells at the end of their path, leaving the tissue they passed through undamaged. This procedure requires the use of a particle accelerator, limiting its availability to a very few locations.