About Prostate Cancer Radiotherapy

It is important to undergo routine screening for prostate cancer. It is a simple blood test checking the level of the Prostate Specific Antigen (PSA). This can be elevated if you have a number of different conditions affecting the prostate and but can also be elevated because of prostate cancer. If found early, you have a very high chance of being cured. A biopsy, done by a urologist will confirm the diagnosis and grade the cancer. This will inform us of its aggressiveness. You may require some imaging studies based on the biopsy and PSA result. This will help stage the cancer. The aim is to check the location of the cancer and if it has spread, then the extent of spread. These scans can include an MRI scan of the prostate, a CT scan of the body, a bone scan and also a PSMA PET scan.

There are many different treatment options for prostate cancer, which most regard as working equally well but some are more suited than others for you and you should have a discussion with a urologist and a radiation oncologist to discuss which is the preferred treatment for you as the procedures, side effects and recovery is different for the different treatments.

The most common treatments are either surgery or radiotherapy, and within these there are different options. There are also other possible treatments which are not routinely pursued or which are not available within New Zealand.

The most common and readily available radiotherapy treatment is that delivered externally with a machine called a Linac. This machine delivers x-rays targeting the prostate and other sites very accurately. The Cyberknife is another machine used to deliver radiotherapy externally and is used to deliver high doses precisely to the prostate over a short period of time. This is not widely available in New Zealand. The two other main types of radiotherapy are delivered internally and these require either a general anesthetic or a spinal anesthetic. They are called seed brachytherapy or high dose rate (HDR) brachytherapy.

Seed brachytherapy is used predominantly in low-risk prostate cancer and uses radioactive seeds. These seeds are the size of rice grains and are inserted into the prostate gland. You will be radioactive and some precautions are needed especially in the first few days after the seeds are implanted. The full dose will be delivered slowly over a period of many months and overall, it gives a high dose to the prostate gland. This approach has the convenience of being a single session but there will be appointments before and after the seed insertions as well.

HDR brachytherapy is an option usually for higher risk prostate cancer. It is different from seed brachytherapy in that you will not be radioactive after the treatment. The radioactive source used to deliver the radiotherapy within the prostate gland is guided through catheters that make channels into the prostate. The source is only in the prostate for a short period of time and moved to different sites to deliver the dose into the prostate. Most often HDR brachytherapy is accompanied by the external treatment through a Linac as well. The treatment has the added advantage over the Linac based treatment as it can give a higher dose to the prostate gland. Both seed brachytherapy and HDR brachytherapy are only suitable in some patients.

Linac based radiotherapy can be of a few different techniques. These include IMRT, VMAT and there are also clinical trials investigating the use of stereotactic body radiotherapy (SBRT) for prostate cancer as well. A major advantage of the Linac based treatment is that the prostate and the pelvic nodal drainage area can be treated. The pelvic nodes may be enlarged due to prostate cancer cells spreading and growing there but can also be normal in size but harbor microscopic nodal metastases. The risk of this possibility will be assessed by your radiation oncologist who may recommend treating the pelvis together with the prostate. The side effects may however be more significant with the larger region being irradiated. Discuss this with your radiation oncologist.

Linac based treatment does require multiple sessions. As we gather more results from studies, there has been a move towards increasing the dose but also at the same time compacting it so that the overall treatment is also shortened. Treatment may range from 4 weeks to 2 months, or even as little as just a week as SBRT becomes more commonplace. Your radiation oncologist may also recommend you be commenced on hormone treatment as well if you have a higher risk prostate cancer as it may improve your outcome.

Cyberknife is a state of the art treatment. It uses robotics and advanced software. The Cyberknife can be thought of as a Linac on a robotic arm. It has some added advantages compared to a conventional Linac and is ideal for treating the prostate with SBRT. It does however require metallic clips called fiducials to be inserted into the prostate, which allows the Cyberknife to then track the prostate, thereby increasing the precision. A clear advantage then is reduced side effects, in particular the urinary side effects from radiotherapy are reduced compared to a Linac. I’ve found this to be the case in my practice, similar to published results from international studies. Using the Cyberknife, my patients complete prostate radiotherapy in 5 days, spread over a week and a half. A great option for men who live far from a treatment center, or who cannot undergo a longer treatment.

Prior to starting external beam radiotherapy, a planning session will be needed. You will receive instructions on the preparation for this and includes drinking enough water to ensure your bladder is filled and also ensuring you have cleared your bowels so your rectum is empty. These simple steps are crucial to ensure you have quality treatment and will minimize the side effects from the treatment. A CT simulation scan is done and this will then be used by your radiation oncologist and radiotherapy team to plan your treatment. You do not need to stay in hospital for the treatment and most people would continue to work during most of the treatment but may need to reduce their activities depending on the side effects they experience. Treatment times vary depending on the technique used. And you can usually drive home as long as you don’t feel too fatigued.

There can be a number of side effects but the duration and severity are dependent on a number of factors. Discuss this with your radiation oncologist. Some of these side effects might be the pivoting point that makes you choose either radiotherapy or a prostatectomy for your treatment.

Common side effects from radiotherapy include:

The risk of the more severe side effects is usually small and may take several years if at all to turn up. The most common side effects of balder bother, bowel bother and fatigue usually resolve within a few weeks after completion of your radiotherapy.

Radiotherapy can treat prostate cancer well with a high degree of success. The best treatment choice is the one that suits you the most. Discuss this with both your radiation oncologist and urologist. You can get further information on the Targeting Cancer website, the EVIQ website and the UpToDate website.

© Ramesh Pandey March 2025