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How is prostate brachytherapy performed?
Prostate brachytherapy is a two stage procedure;
Stage one involves a transrectal ultrasound examination of the prostate, when detailed pictures of the prostate gland are taken. This day case procedure taking approximately 15min and is usually performed under a general anaesthetic. The patient goes home shortly afterwards
These pictures are then loaded into a dedicated planning computer where a 3D model of the prostate is constructed. The precise number and position of the seeds are calculated and ordered individually for each patient. Typically 100-120 seeds are required.
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What are the seeds made of
and how long do they work?
The seeds are tiny canisters of titanium (4.5mm long x 0.8mm diameter) that contain the radioactive isotope iodine125. The canister prevents the radioactive iodine diffusing though the body and so affecting other organs, such as the thyroid gland.
The half-life of radioactive iodine125 is approximately 60 days which means that most of the radiation is released from the seeds over the first three months, although they remain biologically active for approximately 9 months in total. Thereafter they are effectively inert.
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Do I have to have the seeds removed?
No, the seeds are a permanent implant, which do not require removal. Patients are unaware that the seeds are inside them and, they do not set off airport metal detectors!
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What are the advantages of prostate brachytherapy?
Prostate brachytherapy allows a high dose of radiation (145gray, units of radiation) to be delivered directly into the prostate. This dose is substantially greater than can be delivered with conventional external beam radiotherapy (66-75gray) that has to penetrate the body (skin, small intestine, bladder and rectum) before reaching the gland. There is evidence that for some forms of prostate cancer higher doses of radiation can lead to improved cure rates.
The patient has only to visit the hospital twice, once to have the planning scan as a day case and secondly to have the seeds implanted when they stay over night. Patients frequently drive themselves home and return to their daily activities within a few days. This compares to over thirty hospital visits that are required for patients undergoing conventional radiotherapy. Patients having surgery, which is called radical prostatectomy, are usually in hospital for 5-7 nights and are discharged with a urinary catheter in place that is removed 3-4 weeks later. Frequently these patients are off work for 6-8 weeks and most cannot drive for 4 weeks after the operation.
The two most troublesome side effects associated with curative treatments for prostate cancer are those of urinary incontinence and impotence. Radical surgery has the highest rate of inducing these side effects, followed by external beam radiotherapy . Prostate brachytherapy is least likely to induce these side effects.
| Brachytherapy | External Beam Radiotherapy | Radical Prostatectomy | |
| PSA free survival @ 10 years post-treatment | Similar 94 - 50% depending in severity of cancer | ||
| Incontinence | 1% | 3-5% | 8-12% |
| Impotence | 30% | 30-50% | 50-80% |
| Treatment time | 2 days | 6-7 weeks | 5-7 days in hospital |
| Time off work | 3-5 days | 1-3 months | 2-3 months |
However, prostate brachytherapy does have its own specific side effects as detailed below.
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What are the likely side effects of prostate brachytherapy?
Although prostate brachytherapy has fewer side effects compared to other treatment such as surgery or external beam radiotherapy, patients will experience a temporary worsening of their urinary symptoms. These symptoms may include getting up at night to urinate a number of times, a slow urinary stream with urinary frequency and urgency. Medications are given to patients to help these symptoms, which may be present for a number of weeks after the implant. It is often not until 3 months post implant that the patient's symptoms are returning to normal. However, despite these symptoms the patient will be free to continue with their daily activities or work if they wish.
A small number of men (5-10%), often those with troublesome urinary symptoms before treatment, will experience a period of urinary retention where they have difficulty urinating at all. This problem however, can be easily treated, and most patients are able to pass water themselves within a few weeks.
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Is conventional external beam radiotherapy ever given with prostate brachtherapy?
Yes, occasionally in patients with higher PSA levels and whose prostate cancers have a Gleason score of seven or more, a short course of external beam radiotherapy may be given before boosting the radiation dose to the prostate gland by brachytherapy. The external beam can be used to irradiate a wider area around the prostate, which may be beneficial if there is a significant chance that the cancer has spread outside the confines the prostate gland.
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When will I know if it has worked?
Patients are closely monitored after their implant by means of regular PSA blood tests. PSA has been shown to be a very sensitive indicator as to whether there is any active cancer present. Typically the PSA is first measured 3-6 months after the implant although it is the levels at 12 to 18 months that are the most critical, where the PSA should ideally be below 1.0ng/ml.
These levels are of course higher than one would expect following radical surgery as patients still have their prostate gland and the normal benign prostate tissue will continue to release a small amount of PSA into the blood stream.
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How do I know if I am suitable for prostate brachytherapy?
The choice for patients of whether to opt for treatment by prostate brachytherapy is complex and needs to be discussed with ones specialist urologist and or oncologist. For most patients there is not a pressing rush to begin treatment for early prostate cancer and it is important to weigh up all the options.
Guidelines as to whether a patient may be suitable for this type for prostate brachytherapy are listed below:
* Patients should be in good health with a 10+ year life expectancy
* The cancer should be confined to the prostate gland, ie stage 1 or 2 (See
Prostate Cancer Grading).
* The PSA should be below 25ng/ml
* Ideally the Gleason score of the cancer (See
Prostate Cancer Grading) should be below 9
* The prostate size should be less than 50cc (although larger glands can be treated if they are shrunk in size beforehand using hormone treatment)
* Patients must not have had previous prostate surgery, such as a transurethral resection of prostate, TURP. (In this specific group of patients the risk of post-implant incontinence increases from 1% to~20%)
* Patients should have few urinary symptoms and their International Prostate Symptom Score should be less than 20/35
(Click here to find out your own symptom
score)
* Patients should be able to flex their hips to 90
* Patients should not have previously been treated with external beam radiotherapy to their
prostate.
Further Reading on Prostate Brachytherapy is available at the Prostate Cancer Centres website
Part of the Prostate Cancer Centre
Network
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