Radiotherapy has been a key treatment option for men with prostate cancer for decades. An overview of the role of radiation therapy is given in another article on this site. In short, radiation therapy is a cancer treatment that uses the effects of radiation (high-energy rays or particles) to kill cancer cells and shrink tumors. Most men with prostate cancer receive external beam radiation therapy. It focuses beams of radiation from outside of the body onto the prostate gland and the tumor. Receiving each treatment is a little like getting an X-ray or a CT scan, though the radiation used is much stronger.
Over the last two decades, there have been big advances in the technology that radiation oncologists (the doctors who specialize in giving radiation therapy) can use to target the prostate and prostate cancer. Because of this, they can avoid the healthy normal tissues nearby. These approaches, called intensity-modulated radiation therapy (IMRT), are used often. Radiation oncologists may also use repeated imaging before each treatment or systems to track internal seeds or the surface of a patient’s skin. This is called image-guided radiotherapy (IGRT).
These advances have allowed radiation oncologists to deliver radiotherapy in a much more targeted way— focusing on the location they are trying to treat and decreasing effects on nearby structures.
One of the benefits of this more focused radiation delivery is that it has become safer to administer radiotherapy in larger doses. Traditionally, patients with prostate cancer received a relatively small dose of radiation five days each week for up to eight weeks. However, with these technical advances, it is now possible to deliver a similar treatment effect with only a few larger treatments given a few days each week for two to three weeks. This newer approach is called stereotactic body radiation therapy (SBRT). It is also called stereotactic ablative radiotherapy (SABR). This process of breaking the overall radiation treatment course into fewer, larger doses is also called fractionation. SBRT can be referred to as “ultra-hypofractionation.”
SBRT in localized disease
SBRT may be used in a few clinical situations in men with prostate cancer. The most common reason that men would receive radiation therapy after being diagnosed with prostate cancer is as the primary treatment for localized prostate cancer. SBRT is an acceptable treatment option for nearly all categories of localized prostate cancer (ranging from low-risk to very high-risk disease). However, the ideal treatment approach depends on the details of your tumor, your other health conditions, your urinary function, and other considerations. In many cases, a “moderately hypofractionated” approach is recommended. This is somewhat between the traditional 8 weeks of treatment and SBRT. You should speak with your radiation oncologist to determine the best approach for you.
SBRT in metastatic disease
SBRT treatment may be used in two ways for men with metastatic disease. For those men who had a small number of spots where cancer has spread (so-called “low volume” metastatic disease), SBRT may be used to treat the prostate itself. SBRT also may be used to treat sites of disease spread. This so-called “metastasis-directed therapy” may be used along with other treatments for metastatic cancer or to delay having to start (or change) those treatments.
Technological advances have transformed the delivery of radiation therapy over the past few decades. SBRT provides external beam radiotherapy in fewer treatments. The advantages of SBRT include convenience for patients and lower costs for the healthcare system, while still providing very good clinical outcomes. If you are considering radiotherapy for your prostate cancer treatment, you may want to talk to your radiation oncologist about whether it is suitable for you.