Overview of Side Effects
Alas, every treatment for prostate cancer involves a risk of side effects, both short term and long term. There is no magic bullet that produces zero side effects, and you should not trust any treatment which claims to have zero risk of side effects.
CyberKnife does tend to have mild side effects. Many men I see in follow-up at 3 – 12 months report that it is as if they never had the treatment, they are not aware of any residual side effect. Everyone is different however, and there is a wide range of what they experience. Side effects from radiation can be subdivided into short term and long term.
Short-time side effects typically occur from 1 week to 2 months following CyberKnife, and are due to inflammation caused by the radiation. Long-term side effects typically start 6 months or later after the radiation, and are due to scarring and fibrosis.
The most common situation we see is this: During the treatment sessions there are no side effects. A week or two after radiation, the urination becomes a little more frequent with mild burning and more frequent urination. This lasts a month or so. By the 3 month mark the patient has recovered pretty much fully, and reports no remaining side effects. In the years that follow, the erections may be weaker and the patient may request a Viagra or Cialis prescription. The occasional patient reports more severe side effects during and after the CyberKnife treatment, such as more severe slowing of the urine stream, or greater discomfort.
Common Short Term Side Effects
- Urinary bother: frequent urination, some burning, getting out of bed frequently to urinate, weak stream, dribbling
- Rectal irritation: more frequent bowel movements, some rectal mucous, hemorrhoid irritation
- Small amounts of blood in the urine
- Some blood and discomfort occurring during sex / ejaculation
Uncommon Short Term Side Effects
- Urinary blockage requiring a urine catheter or self-catheterization for a few weeks
- Infection, which can be caused by placement of Marker Seeds or SpaceOAR
- Feeling of pressure or discomfort in the rectum from the SpaceOAR gel
- Discomfort or pain in the prostate gland
Common Long Term Side Effects
- Weakening of the erections in many. Erectile dysfunction in about one third.
- Narrowing of the urethra (urine passage) causing a little slower stream
Rare / Uncommon Long Term Side Effects
- Incontinence, ie. urine leakage
- Long term urine catheter use (rare)
- Chronic pain
- Rectal bleeding
- Severe narrowing of the urethra, requiring dilatation or TURP.
- Fistula between prostate and rectum requiring a colostomy (Rare. To my knowledge, I have never had this happen to any of my patients.)
Managing the Side Effects Short Term Urinary Symptoms
We usually routinely prescribe tamsulosin (Flomax) for about three months, starting when you start your CyberKnife treatments. This medication helps relax the bladder and urine passage, and generally makes the urine flow easier, and reduces the number of times you get out of bed at night to use the bathroom. It can also reduce the burning a little. The usual dose is one tablet daily, but it can be increased to two tablets daily. If the urine burning is annoying, we prescribe pyridium (Azo) an over the counter pill that you take by mouth, and the body excretes it in the urine and it numbs the urine tract a little. Over the counter anti-inflammatories such as naproxen (Aleve) are also helpful in reducing some of the irritation.
Long Term Urinary Symptoms
Flomax can be taken long-term if needed. If the long-term symptoms are very troubling, then sometimes a TURP (trans-urethral reaction of prostate tissue) is performed. The urologist places an instrument up the penis and widens the urine passage (urethra) as it passes through the prostate. It is important that as little tissue be removed as possible, as doing a TURP after radiation therapy can increase the chance of urine leakage. Other options are to try to stretch the urethra with a procedure called dilatation. Self catheterization, I.e learning to insert a catheter through the penis and up to the bladder, is also an option for the most severe cases.
CyberKnife can cause impotence / erectile dysfunction in about 1/3 of patients by the the 5 year mark. Although CyberKnife does not destroy the erection nerves, it can damage them and affect the blood flow into the penis. Rather than being a short-term side effect, erectile dysfunction (ED) is a long term side effect of radiation and tends to be permanent if it occurs. It can take several months or years for ED to develop. Medications like Viagra and Cialis can be prescribed. Cialis is also available in a lower daily dosage (5mg) and this can help both urinary symptoms and sexual symptoms. Other options include the vacuum pump, which can be used in combination with Viagra / Cialis. Self-injection therapy with needles is typically the next step if the pills do not work. There are also penile implant surgeries available.
Comparison with Other Treatment Options
- Cyberknife tends to have the same side effects as a 9 week course of conventional radiation (IMRT).
- Radiation produces less risk of impotence and incontinence then does surgery. It has less risk of urine leakage than surgery.
- Proton therapy has been shown to cause more rectal side effects in some studies.