The term urinary dysfunction encompasses both urinary incontinence, which can range from some leaking to complete loss of bladder control, and irritative voiding symptoms, including increased urinary frequency, increased urinary urgency, and pain upon urination. Obstruction of the bladder by an enlarged prostate is the typical reason for these symptoms initially; however, after therapy, these symptoms are typically caused by damage to the nerves and muscles that control urinary control.
For men undergoing prostatectomy, incontinence is the primary urinary side effect. On average, about 25% of men report frequent leakage or no control and a need to use absorbent pads at six months after treatment; by three years, fewer than 10% report using pads at all. Up to 30-50% of men with normal baseline function will report some increase in urinary symptoms and urgency after prostatectomy. This seems to be reduced if a nerve-sparing technique is performed.
External beam radiotherapy can irritate both the bladder and the urethra, causing inflammation or swelling of the prostate. Most of the symptoms lessen over time with little or no intervention: nearly 45% of men report irritative voiding symptoms after six months, and the majority resolve by one year, with less than 10% of men still requiring pads after three years. However, up to 20-40% of men with normal baseline function will continue to experience an increase in urinary symptoms.
Urinary dysfunction following brachytherapy tends to be more severe initially. Over 70% of men have symptoms requiring pads or medication within six months after seed implantation, but the rate drops to 25% or less after two years and to under 10% by three years. However, 20-40% of men with normal urinary function at baseline will have persistently increased urinary symptoms 3 years after receiving brachytherapy.
Some form of urinary dysfunction is normal following initial therapy for localized prostate cancer. But it’s important to realize that not all symptoms are normal, and that some require immediate care. Continuing to work with your urologist to optimize your urinary function is an important part of your ongoing care.

Management of Urinary Dysfunction

Because the urinary symptoms following radiation therapy are irritative in nature, drugs that improve urinary flow are commonly used. Tamsulosin (Flomax), terazosin (Hytrin), and other alpha-blockers are typically instituted in all men following radiation therapy for at least a few weeks, and are gradually withdrawn as symptoms improve. Anticholinergic medications like tolterodine (Detrol) or solifenacin (Vesicare) can help treat irritative bladder symptoms as well.

In cases of persistent urinary incontinence, the least invasive procedure consists of an injection of collagen into the urethra. This tightens the passageway, making it more difficult for urine to leak through. Although over 50% of men stay dry with this procedure, the effects only last for a short time.
Longer lasting results are seen with surgical procedures. In this procedure, a sling made from silicone or, more rarely, human tissue is slipped under the urethra and anchored to the muscle or bone, relieving the urethra from pressure buildup in the abdomen as urine accumulates in the bladder.
The sling results in urinary function improvements in about 70% of men after prostatectomy, although only about half of those reported being completely dry after four years. Following radiation therapy, only 30% of men showed an improvement, with even fewer men reporting being completely dry after four years.
 

Source: http://www.pcf.org/site/c.leJRIROrEpH/b.5814053/k.1572/Urinary_Dysfunction.htm