Prostate disease

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48 Prostate disease

Key points

Benign prostatic hyperplasia

Pathophysiology

The prostate is a part glandular, part fibromuscular structure about the size of a walnut that surrounds the first part of the male urethra at the base of the bladder (Fig. 48.1). In simple terms, the prostate can be divided into a lobular inner zone encapsulated by an external layer. The inner zone is where benign hypertrophic changes are generally found, whereas most malignant changes originate in the peripheral zone.

Prostatic hypertrophy is directly related to the ageing process and to hormone activity. Within the prostate, testosterone is converted by 5α-reductase to dihydrotestosterone (DHT). DHT is five times more potent than testosterone and is responsible for stimulating growth factors that influence cell division leading to prostatic hyperplasia and enlargement.

Histologically, depending on the predominance of the type of prostatic tissue present, prostatic hypertrophy can be stromal, fibromuscular, muscular, fibroadenomatous or fibromyoadenomatous.

As the prostate enlarges, it can compress the urethra (Fig. 48.2) and this, together with increased adrenergic tone, can lead to bladder outflow obstruction (BOO) and lower urinary tract symptoms (LUTSs). Therefore, the term BPH includes benign prostatic enlargement (BPE), the clinical features associated with urinary obstruction and LUTSs.

Examination and investigations

There is a range of investigations and diagnostic tests available for the evaluation of patients with suspected BPH. Some tests are standard during the assessment of all men with LUTSs. Other investigations are optional and are only performed depending on the patient’s presentation and the clinician’s judgement.

Treatment

Most men over the age of 50 years exhibit some of the symptoms of BPH. The range of treatment options for the management of BPH includes watchful waiting, medical therapies and surgical interventions. The key issue, therefore, is deciding who should be treated and when.

The British Association of Urological Surgeons has published guidelines for the management of BPH in primary care (Speakman et al., 2004), focussing on when urological referral is required and when non-invasive treatment can be initiated (Fig. 48.3).

image

Fig. 48.3 Algorithm for the treatment of lower urinary tract symptoms (LUTSs) in males in primary care (from Speakman et al., 2004) (DRE, digital rectal examination; MSU, mid-stream urine sample; PSA, prostate-specific antigen).

Therapeutic management

The principal treatment options are α-adrenoceptor blocking drugs, 5α-reductase inhibitors and combination therapy. Phytotherapy is also used in the management of BPH, although the benefits remain unproven.

α-Adrenoceptor blocking drugs

The prostate gland is very responsive to adrenergic stimulation. In fact, prostatic outlet obstruction in BPH is partly due to the hypertrophied bulk of the gland, but it also arises from an increase in adrenergic tone. In the prostate, α1-receptors predominate and mediate the contraction of the gland’s smooth muscle. At least three subtypes of this receptor exist (α1A, α1B and α1D). The α1A is thought to be the dominant receptor in the prostate, although its role clinically has still to be confirmed. This increase in sympathetic tone is potentially reversible by α-adrenoceptor antagonists.

In general, all the agents are considered to produce similar clinical improvements of LUTSs and urinary flow. Benefits can be seen usually within the first few days of therapy and can be maintained in the long-term. α-Adrenoceptor antagonists also have a comparable side-effect profile, which includes postural hypotension, dizziness, fatigue, headache, drowsiness, nasal congestion and ejaculatory dysfunction.

Patients with BPH frequently experience erectile and ejaculatory dysfunction. The treatment of BPH should also aim to improve sexual function. However, the effect of α1-adrenoceptor antagonists on male sexual function is variable and influenced by the choice of agent and patient characteristics (Van Dijk et al., 2006).

Tamsulosin

Tamsulosin is a selective inhibitor of the α1A– and α1B-adrenoceptor. It has an elimination half-life of about 13 h and is available as a prolonged release formulation that allows once-daily dosing. There is no requirement to titrate the dose upward when initiating treatment. Although the side-effect profile of tamsulosin is similar to other α1-adrenoceptor antagonists, it is normally well tolerated (O’Leary, 2001). Intraoperative floppy iris syndrome (IFIS) has been reported during cataract surgery in men treated with tamsulosin, as it is highly selective to iris dilator muscle (Chaim et al., 2009). IFIS can lead to complications and poor outcomes during cataract surgery. As a result, it is essential that patients inform their cataract surgeon that they are taking tamsulosin during the pre-operative assessment. It has been recommended to avoid starting treatment and to discontinue treatment with tamsulosin 1–2 weeks before cataract surgery.

Alfuzosin

Alfuzosin displays a higher selectivity for the prostate compared with tamsulosin or doxazosin. It has a half-life of 5 h, but it is available as a once-daily formulation. It has a rapid onset of action and good tolerability (MacDonald and Wilt, 2005). It reduces the overall clinical progression of BPH and it appears to have a sustained beneficial effect on quality of life (Roehrborn, 2006). Alfuzosin has the least effect on ejaculatory function. Alfuzosin should not be co-administered with potent inhibitors of cytochrome P450 3A4 such as itraconazole, ketoconazole and ritonavir, since this can lead to a several fold increase to exposure in alfuzosin.

5α-Reductase inhibitors

The primary androgen responsible for the development and progression of BPH is DHT. There are two isoenzymes of 5α-reductase: type 1 is found in most 5α-reductase producing tissues such as the liver, skin and hair; type 2 is predominant in genital tissue, including the prostate. 5α-Reductase inhibitors downregulate prostate growth by blocking the conversion of testosterone to the more potent DHT.

The two agents currently available in this group are finasteride and dutasteride. Both have been shown to reduce prostate volume, to improve symptom scores and flow rates, and reduce the incidence of complications such as acute urinary retention (AUR) and the need for surgical intervention to treat BPH (Roehrborn et al., 2000, 2002). Improvements in LUTSs are normally seen after the first 6 months of treatment and are sustained during continuous treatment (Lam et al., 2003).

Combination therapy

It is well established that α-adrenoceptor antagonists are best for managing acute symptoms but have no impact on reducing the risk of complications such as AUR or progression to prostate surgery. In contrast, 5α-reducatase inhibitors have little impact on short-term acute symptoms but reduce prostate size, improve urinary flow and obstructive symptoms in the long-term. Furthermore, α-adrenoceptor antagonists are effective regardless of prostate volume, whereas the 5α-reductase inhibitors are more suited for the management of LUTSs in men with large prostates. In terms of long-term benefits, continued treatment with 5α-reductase inhibitors decreases the risk of AUR and BPH-related surgery. Therefore, it appears logical to use a combination of an α-adrenoceptor antagonist and a 5α-reductase inhibitor to manage acute symptoms and reduce progression of BPH.

The benefits of using a combination of doxazosin and finasteride compared to monotherapy have been demonstrated in over 3000 men (McConnell et al., 2003). Similarly, the combAT trial (Roehrborn et al., 2010) involved nearly 5000 men with moderate to severe symptoms of BPH and prostate enlargement treated with a combination of dutasteride and tamsulosin. This study demonstrated a significant improvement in BPH symptoms over a 4-year period when compared to either agent used alone. The combination was also found to reduce AUR and progression to BPH-related surgery and, although superior to tamsulosin with respect to these complications, combination therapy was not better than dutasteride. Overall, the adverse events associated with combination therapy were few and treatment was well tolerated.

Combination therapy with an α-adrenoceptor antagonist and a 5α-reductase inhibitor has now been adopted widely into routine practice for the early management of LUTSs and to reduce progression of BPH.

Surgical treatments

Surgical interventions are commonly performed in men with LUTSs caused by BPH that have failed to respond to medical treatment. Surgery is also indicated in patients who develop complications such as intractable or recurrent urinary retention, renal impairment, persistent haematuria, recurrent UTIs or bladder stones.

Patient care

Patients generally seek medical help for BPH because of the impact of symptoms on their quality of life. Most men tolerate a high degree of symptoms and impact on daily activities before they seek help. Table 48.1 lists some common therapeutic problems in the management of BPH. Patients should receive information about the management options available, the investigations that they need to undergo and possible treatment outcomes and adverse effects. Patients receiving drug therapy should receive specific information about their treatment, including potential benefits, timeline of expected outcomes and possible side effects.

Table 48.1 Common therapeutic problems and proposed management strategies in benign prostatic hyperplasia

Problem Solution
Patient taking α-blocker still symptomatic after 2 weeks Patients should be advised that it may take 2–6 weeks before symptomatic treatment relief is seen
Patient taking an α-adrenoceptor blocker complains of cardiovascular adverse effects such as dizziness, syncope, palpitations, tachycardia or angina These side effects are more likely in elderly patients. They are most common after the first dose and reflect the hypotensive effects of the drugs. They can be reduced by titrating the dose or using more uroselective drugs such as tamsulosin
Sexual dysfunction Decreased libido or impotence can occur in patients taking finasteride and dutasteride. Abnormal ejaculation can be caused by α-blockers. Tamsulosin in particular can cause a dry climax (retrograde ejaculation). Patients should be forewarned when discussing treatment options
Patient taking finasteride notices breast enlargement Unilateral or bilateral gynaecomastia is a frequently reported side effect with finasteride and patients need to be counselled accordingly when discussing treatment options
Patient taking finasteride or dutasteride has a sexual partner who is pregnant Exposure to semen should be avoided as both drugs can cause abnormalities to genitalia in a male fetus. The patient should be advised to use a condom

There are two websites which produce particularly useful educational material on prostatic disease: the Men’s Health Forum (http://www.menshealthforum.org.uk/) and the Prostate Research Campaign (http://www.prostateuk.org/index.htm).

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