Why do prostate cancer treatments cause urinary incontinence?

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Depending upon the experience of the surgeon, as many as 40 percent of patients will suffer from post surgery urinary incontinence, a potentially devastating loss of urinary control.

The underlying cause of post-prostatectomy incontinence is weakness in the urinary sphincter, a ring of muscles that control the flow of urine from the bladder. Though the exact cause of this sphincter deficiency is not known, we do know that the experience of the surgeon performing the radical prostatectomy has a tremendous impact. Higher-volume surgeons do have better results with a lower risk of incontinence.

Dr. Marc B. Garnick, MD
Hematologist & Oncologist

Urinary incontinence (the involuntary leakage of urine) is a common and embarrassing side effect of prostate disease and its treatment. For men who have had a prostatectomy (surgery for prostate cancer), urine leakage is a frequent side effect but often subsides gradually over the first two years following surgery. Although irritation, burning and painful urination are the most common urinary side effects of radiation therapy, incontinence—though uncommon with a highly skilled radiation oncologist—can also occur.

If you experience urinary problems following prostate cancer treatment, your doctor may recommend a urodynamic evaluation—a diagnostic session to help determine the nerve and muscle function of your bladder and urethral sphincter (the ring-like muscle that controls urine flow). This will help pinpoint the exact nature of the problem so that your therapy can be specifically designed to address it.

Because the most common and troubling harms of surgery have to do with two basic bodily functions, the ability to control one's bladder and to have sex, there is a good possibility of suffering at least some erectile dysfunction (impotence) or urinary incontinence as a result of prostate cancer treatment.

Between 20 and 63 out of 100 men will require pads or clamps following surgery to control urinary dripping. For most it is mild, requiring no more than one protective pad per day. For some there is “stress incontinence,” the inability to control urine under stress (e.g., physical exertion, laughing, sneezing, etc.); this may occur in about 10 out of 100 cases. Severe incontinence, necessitating continuous wearing of protective pads, is unusual, occurring in about 1 to 7 out of 100 cases. Some men (perhaps 5 in 100) eventually require surgery to correct their urinary difficulties.

Nerve-sparing surgery may reduce the likelihood of mild incontinence in younger men to about 10 out of 100. Urethral strictures, which require at least one procedure to dilate the urethra, may develop due to scar tissue formation in about 10 to 20 out of every 100 cases.

The prostate sits between the bladder and the urethra and urine actually passes through the prostate on its journey from the bladder to the penis (i.e., penile urethra). Think of the prostate (or prostatic part of the urethra) as a tunnel that connects New Jersey and Manhattan. If you remove part of the tunnel, you have to reconnect the two sides and build a new makeshift tunnel. As tissue is healing from this type of surgery and the muscles that control the flow of urine are recovering, men will often suffer from incontinence.

The prostate sits between the bladder and urethra and helps maintain continence. Since surgery removes the prostate, radiation kills the cancer by damaging the prostate, and hormone therapy causes the prostate to shrink, prostate cancer treatments interfere with this mechanism.
 

The close relationship between the prostate and bladder is responsible for the increased rates of incontinence following prostate cancer therapy. Normally urinary continence is maintained by muscles which surround the urethra at its junction with the bladder. In the male, the prostate sits at the base of the bladder where it wraps around the urethra, and as such is in close proximity to the muscles which control urine flow.

With radiation therapy, ionized wave particles are responsible for killing the tumor cells, and unfortunately neighboring cells, such as those involved in urinary control, are also affected resulting in the loss of continence. In the case of prostate surgery, a portion of the urethra, which is encircled by the prostate, is removed and the urethra must be reconnected. During the dissection of the urethra it is possible to damage the muscles responsible for urinary control. However, with improving technology, such as the introduction of robotic assisted laparoscopic prostatectomy, the surgeon is able to better visualize these muscles, resulting decreased rates of incontinence.

It is important to discuss your concerns regarding possible incontinence with your physician, in order to gain a thorough understanding of realistic expectations and the possible treatments available for incontinence.

The urinary sphincter muscle that provides urinary control is very close to the bottom of the prostate gland and any treatment for prostate cancer can lead to damage or injury of this structure. The consequence of this damage is urinary incontinence which may be temporary or permanent.

The prostate lies in the pelvis and lies between the penile urethra and the urinary bladder. Urinary continence relies on coordination of two mechanisms, the involuntary (smooth muscle) and the voluntary (skeletal muscle).

The prostate literally rests on top of the voluntary urinary sphincter and is lies below the involuntary urinary sphincter that derives from the bladder. As you can imagine, any treatment delivered to the prostate can thus lead to urinary incontinence.

The degree, severity and probability of having short or long term urinary incontinence clearly depends on the degree of impact on these two continence mechanisms and the patient's underlying bladder physiology.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.