Harvard Men's Health Watch

Medical memo: High-dose radiotherapy for prostate cancer

Medical memo

High-dose radiotherapy for prostate cancer

Radiation therapy for prostate cancer has been a well-established option for men with early prostate cancer for many years, but advances make it more attractive than ever before. One major improvement is high-dose therapy.

All forms of radiation contain energy; it's what boils water in a microwave oven and what burns your skin after an ill-advised day at the beach. Radiotherapy delivers much more energy, enough to kill cells. Because cancer cells are growing faster than normal cells and are less able to repair radiation damage, radiotherapy can be used to treat many forms of cancer. The trick is to focus the radiation on the tumor as precisely as possible, thus minimizing damage to healthy tissues in the neighborhood. In the case of prostate cancer, doctors can focus the energy of radiation from outside the body (external beam radiation) or from the inside, by placing radioactive seeds inside the prostate (brachytherapy). Both techniques rely on high-tech methods of imaging the prostate to produce precise maps of the gland.

In the case of external beam therapy, the goal is to deliver energy to the prostate while protecting the bladder and rectum. After a man chooses external beam therapy, his first step is to undergo a computed tomography (CT) scan. The CT image is relayed to a computer that constructs a precise, three-dimensional map of his prostate and seminal vesicles. The map allows the radiation oncologist to target precisely the cancerous tissues while shielding the healthy tissues nearby.

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