Radiotherapy for Prostate Cancer

Radiotherapy (or radiation therapy) is a type of prostate cancer treatment that directs high doses of radiation to cancer cells to damage and kill them. Current techniques have been designed to minimize risk to your healthy tissues. As your prostate cancer advances, your doctor may also recommend combining radiotherapy with androgen deprivation therapy at the same time.

A few options for prostate cancer radiotherapy are available.

External radiation therapy is frequently relied upon for treating prostate cancer, and delivers radiation to your tumor by machines surrounding your body. Traditionally, it is carried out over multiple sessions taking between 2 weeks and 2 months.

• Intensity modulated radiation therapy (IMRT)

Currently, this is the most common prostate cancer radiotherapy delivered externally. Here, 3D imaging guides your doctor to direct radiation beams according to the shape of your tumor while adjusting the strength of each beam to maximize radiation being delivered to the tumor while minimizing the amount of radiation reaching nearby healthy tissue. Up to 40 sessions may be needed.

• Stereotactic body radiation therapy (SBRT)

This is an alternative to IMRT that delivers high doses of radiation to tumors across a few treatment sessions, also known as Gamma Knife, X-Knife or CyberKnife. Generally, it is much shorter and cheaper, and recent data is fast making this the recommended standard of care for prostate cancer radiotherapy in the US and Europe.

• High-dose rate (HDR) brachytherapy

This is a treatment that delivers radiation directly into your tumor, while avoiding the healthy tissues surrounding it. It involves temporarily placing sources of radiation directly into your prostate (e.g. needles or tiny “seeds”), to deliver high amounts of radiation to the target site over a few minutes.

• Low-dose rate (LDR) brachytherapy

Here, tiny devices called “seeds” about the size of rice grains will be inserted into your prostate, and left to deliver radiation over an extended period of time. This procedure can be temporary (removed after a few hours or days) or permanent (left until radiation finishes).

Radiopharmaceuticals are used as radioactive prostate cancer treatments that are injected into your body. They kill cancer cells by emitting particles of radiation which damage genetic material of the cancer cell. Radiopharmaceuticals in particular are uniquely designed to specifically target cancer cells and avoid healthy tissue.

• Radium 223

Radium 223 is a radioactive isotope, an unstable version of a chemical element that decays over time, emitting radiation which targets and eliminates bone metastases. It is approved by the FDA for treatment in advanced castration resistant prostate cancer.

• ¹⁷⁷Lu-PSMA-617

In ¹⁷⁷Lu-PSMA-617, a radioactive atom is combined with a small molecule designed to target prostate cancer cells with high levels of prostate-specific membrane antigen (PSMA), ensuring that the radiation delivery is highly specific. This treatment was recently approved by the US Food & Drug Administration in 2022 for advanced castration resistant prostate cancer.