What is the prostate?
The prostate gland is a small, solid gland roughly the size of a walnut, located behind the pubic bone. It is situated beneath the bladder, surrounding the first part of the urethra. Approximately 0.5ml of each ejaculate is fluid made by the prostate, containing a number of substances that nourish the sperm and are necessary for fertility. Two small pouches, the seminal vesicles, sit directly behind the prostate, and provide a further 2ml of ejaculatory fluid via small tubes that run through the prostate into the urethra.
Cancer is a condition in which the growth of normal cells becomes uncontrolled for reasons not entirely understood. These cells continue to divide, creating a tumour which at first grows locally within the prostate, then may spread via the lymphatics (small channels throughout the body containing lymph fluid) or bloodstream to more distant parts of the body. Prostate cancer most commonly affects the outer part of the gland, and is often slow-growing over many years. It does not usually cause any symptoms until it is locally advanced or has spread to other parts of the body. One in six Australian men is diagnosed with prostate cancer in his lifetime, and it is the second most common cause of death from cancer in men.
This is a gradual enlargement of the central portion of the prostate that compresses the urethra and causes obstruction to urine flow, giving rise to various symptoms, including a weak urine flow and urgency. BPH is not cancer, and does not turn into cancer.
Prostatitis may or may not be due to infection. Severity of symptoms ranges from none to severe frequency of urination, burning pain during urination, difficulty voiding, and even complete inability to void (acute retention). If the prostate is infected, it can be a source of recurring urine infections, particularly in the setting of co-existent BPH and urinary obstruction.
What is PSA?
One of the substances secreted into the ejaculate by the prostate, Prostate Specific Antigen (PSA), is made in larger amounts when prostate cells become cancerous, and can be measured in the blood. This is therefore used as a screening test for prostate cancer. It is not a perfect test however, and only around a third of men with an elevated PSA go on to have a diagnosis of prostate cancer made. Causes of an increased PSA other than cancer include:
- Urine infection
- Urethral catheter
Professor Mark Frydenberg AM discusses the PSA blood test used to detect prostate cancer.
Who is at risk of prostate cancer?
- Family history: Those with a first degree relative (brother or father) are around 2-3 times higher risk than normal, and this increases if more than one relative is affected
- Age: the risk of prostate cancer increases with age, less common in men under 50
- Genetics: Prostate cancer is more common in Africans and rarer in Asians
- Dietary factors: There appears to be a link between prostate cancer and men consuming large amounts of dietary fat.
What are the symptoms of prostate cancer?
As prostate cancer affects the outer part of the gland most commonly (i.e. away from the urethra), it does not cause symptoms until it is advanced. As such it is often recommended to test asymptomatic men to ‘catch’ the disease early in its course when there is the greatest chance of cure. Urinary symptoms are more often due to co-existent BPH, such as:
- Hesitancy (difficulty starting urination)
- Poor or intermittent urine flow
- Feeling of the bladder not emptying completely
- Feeling of not being able to hold on (urgency)
- If prostate cancer spreads to other parts of the body, such as into the bones, it may cause pain in these areas.
After taking a history for risk factors and symptoms, the prostate can be examined by passing a finger into the rectum (digital rectal examination, or DRE) and feeling the back of the prostate through the front wall of the rectum. Any cancers large enough to cause a lump in this part of the gland will be palpable (felt). An abnormality on DRE, or a raised PSA may raise the suspicion that prostate cancer could be present. The next step is to sample some of the prostatic tissue to examine under the microscope by doing a prostate biopsy. Alternatively, cancer may be diagnosed by chance when analyzing prostate tissue surgically removed to ‘unblock’ the flow of urine (as in transurethral resection of the prostate or TURP).
Under sedation or local anaesthesia, an ultrasound probe is passed into the rectum to visualize the prostate. This allows a fine needle to be passed into the prostate, via the probe (and through the rectal wall), to sample a very fine core of tissue for analysis. It is important to note that most cancers are not visible on the ultrasound, and this biopsy therefore is simply a sample of prostate tissue. For this reason, multiple samples are taken from the prostate, systematically from different areas. If an abnormal area is palpable on DRE, more samples of this area can be taken. The main discomfort to the patient is the feeling of the ultrasound probe in the rectum, and the risk of complications such as heavy bleeding in the stools or urine, or severe infection, is around 2%.
Further tests: If a diagnosis of prostate cancer has been made, your doctor may order tests to assess whether the cancer is still localized to the prostate, or if it has already spread to other parts of the body. Such tests may include a bone scan, to look for cancer within the bones, and a CT scan, to assess organs and lymph nodes within the abdomen.
These are used to determine how advanced or aggressive the cancer is and therefore the likelihood of cure with treatment such as surgery or radiotherapy.
The stage refers to how far the prostate cancer is spread, and a classification system commonly used in Australia is outlined below in a simplified form (By convention, the prefix T is used to denote the tumour stage, e.g. T1 or T2).
T1 the cancer is too small to be felt on rectal examination. It has been diagnosed either through biopsy after an elevated PSA, or by chance after transurethral prostate resection.
T2 the cancer is large enough to form a palpable lump on rectal examination, but is still confined to the prostate gland.
T3 the cancer has spread outside the gland and possibly into the seminal vesicles.
T4 the cancer has spread to involve structures around the prostate, such as the rectum, bladder, or pelvic muscles.
The grade of a cancer is how aggressive the cells look under the microscope, and in prostate cancer is given a Gleason score. As prostate cancer is often multifocal, consisting of multiple spots of cancer within the prostate rather than one single tumour, separate areas of cancer can have different appearances. To give a Gleason score, the two appearances most commonly seen are each graded from 1 to 5 by the pathologist, giving a potential minimum total score of 2 and maximum of 10 (most aggressive). However, it has been realized that scores less than 6 can be inaccurate so that nowadays the minimum Gleason score given is 6, indicating the least aggressive-looking grade of cancer.
There are many ways to treat cancer that is still confined to the prostate (T1 or T2) and there is still no definitive agreement as to which is the best. One of the reasons for this is that patients with early stage disease may live 10 years or more if no treatment is used, whereas in others the disease can be more serious and progress quickly. While we can generalize, it is impossible to predict with certainty for any one individual the course their particular cancer may take. The first thing to note is that you should not feel pressured to make a decision. When prostate cancer is detected early, there is plenty of time to explore your options, and it is not uncommon for patients to take a few weeks or even months to decide upon which treatment they would prefer. Treatment options are summarized below.
If prostate cancer has been diagnosed very early, or incidentally during transurethral prostate resection, a ‘wait and see’ policy may be chosen to assess if the cancer is growing quickly enough to warrant treatment. The idea is to avoid unnecessary treatment which comes with its own risks to quality of life. This does not mean doing nothing, but involves a regime of regular PSA tests and sometimes repeat prostate biopsies to monitor the cancer. If treatment is ultimately required, it is in the form of curative treatment, such as surgery or radiotherapy.
This is the traditional form of treatment for prostate cancer, and involves removal of the entire prostate gland along with the seminal vesicles. The urethra is then reattached to the bladder outlet. The nerves supplying erectile function to the penis run alongside the prostate, but can often be spared, depending on various factors, giving the best chance of recovery of erectile function post-operatively. For cancer confined within the prostate, radical prostatectomy offers complete removal and subsequent analysis of the specimen for a more accurate prediction of cure. Following surgery the PSA drops to undetectable levels and is monitored closely. A rise in PSA after surgery is an indicator of very early cancer recurrence, and this may be further treated with radiotherapy in some patients.
Radical prostatectomy can be performed using open surgical or minimally invasive techniques. The open approach usually involves one longer incision below the umbilicus (belly button). The minimally invasive techniques involve laparoscopic (keyhole) surgery and can be performed with or without the help of a robot. Several very small incisions are made across the abdomen to introduce the long instruments through “ports”. Nerve-sparing can be performed via any of these techniques.
Risks of radical prostatectomy include cancer recurrence, erectile dysfunction, and urinary incontinence.
Radiotherapy is the delivery of radiation to the prostate, aiming to destroy the cancer cells, with minimal impact on surrounding normal structures (bladder, urethra and rectum). It can also be used in a palliative setting, directed at areas of cancer outside the prostate, e.g. for relief of bone pain due to cancer spread. Radiotherapy can be administered like an X-ray, by directing the beam from outside the body onto the prostate (external beam radiotherapy), or by inserting radioactive ‘seeds’ or needles into the prostate (brachytherapy). Following radiotherapy, the PSA slowly declines and is monitored to assess the success of treatment, although this can take up to 12-18 months.
Risks of radiotherapy include cancer recurrence, erectile dysfunction, urinary symptoms such as frequency, urgency and difficulty voiding, and rectal symptoms such as diarrhoea and rectal urgency.
This is one of the newest of treatments for prostate cancer, and involves destruction of prostate tissue by ultrasound waves which are delivered via a rectal probe. These high energy waves are focused onto the prostate to generate temperatures >80 degrees, killing exposed cells, and the areas being treated can be simultaneously viewed on a screen by the treating surgeon. At this stage it is most often used in patients who have recurrence following radiotherapy, or those not appropriate for surgery or radiotherapy, as the success rates and long term effects are unknown.
Risks of HIFU include cancer recurrence, erectile dysfunction, urinary symptoms and injury to the rectum.
This treatment is usually offered to patients in whom the cancer has spread beyond the prostate, e.g. to lymph nodes or bone. Prostate cancer is partly driven by the male hormone, testosterone, which is made by the testicles. By stopping the production of testosterone, the cancer usually significantly shrinks in size throughout the body, and is held dormant for a period of time that may last many years. Ways to achieve this consist of either:
- Surgically removing the testicles (orchidectomy)
- Taking medications, or 3-6 monthly injections to ‘turn off’ the testicles
The effectiveness of treatment can be monitored by the PSA reading, which quickly drops in most patients. Side effects are those of a loss of the male hormone and are similar to the menopause experienced by women as they lose their female hormones. These may consist of fatigue, loss of libido, loss of erections, hot flushes, tender or enlarged breast tissue, loss of muscle bulk. Over time the bones may lose strength (osteoporosis) with increased risk of fracture, and therefore it is recommended to have regular bone density scans. Hormonal therapy is not a cure, as with time the cancer begins to grow again despite the treatment, but is an effective control that in some patients can last for a long period of time.
Which treatment should I choose?
On top of the shock of being diagnosed with cancer, the array of possible treatment plans can leave patients feeling very confused as to which is most appropriate for them. Some patients feel surprised at being offered a choice of treatments and naturally feel inadequately prepared to make such an important decision. It may be worthwhile seeking additional consultations to discuss options, as well as second opinions from other specialists before coming to a decision.