A client with prostate cancer is experiencing frequent urination but voids only small amounts. What is the likely cause of this symptom?

The symptom of frequent urination with the output of only small amounts is likely attributed to urinary retention. In the context of prostate cancer, the prostate can become enlarged due to the tumor's presence or as a side effect of treatment. This enlargement can compress the urethra, impeding the normal flow of urine and leading to a sensation of urgency or frequent need to urinate, even when the bladder is not full enough to warrant such an urge.

The bladder may become overactive in response to this blockage, causing the urge to void more often, but the inability to empty it completely results in only small amounts of urine being expelled. Therefore, urinary retention is a key factor explaining the client's symptoms.

The other options do not align as closely with the symptom described. Edema refers to swelling due to fluid retention, dysuria involves painful urination, and suppression could imply an absence of desire or ability to urinate but does not accurately capture the situation of frequent, yet ineffective, voiding as seen in urinary retention.