What is prostate cancer?
Prostate cancer is a condition that is diagnosed in 20,000 Australian men each year and sadly 3,300 men will die of it each year. This makes prostate cancer the second most common cause of male cancer deaths in Australia.
Prostate cancer is a significant public health issue and the second most commonly diagnosed cancer in Australian men after non-melanoma skin cancer. There is a 1 in 7 chance of being diagnosed with prostate cancer by the age of 75 and a 4% chance of dying of prostate cancer.
However, it is important to understand that not all prostate cancers are the same. It actually represents a spectrum of disease from the very aggressive cancers to the indolent, slow growing tumours that men “will die with rather than from”.
What are the symptoms?
Typically, there are no symptoms of early stage prostate cancer. Prostate cancer usually occurs around the periphery of the prostate gland and so it does not cause any symptoms until it is very advanced.
As it is asymptomatic during the early stages, the only way to identify aggressive tumours whilst they are still curable is with screening. If we wait until patients become symptomatic then this means the cancer has probably spread from the prostate and is likely incurable.
Can prostate cancer be prevented?
Prostate cancer cannot be prevented. Trials assessing supplements such as selenium and vitamin E which were thought to prevent prostate cancer unfortunately did not demonstrate any benefit. Currently there are no preventative strategies for prostate cancer. So, the best way to reduce mortality and morbidity from this disease is by identifying lethal prostate cancers at an early stage and by treating them more effectively.
How is prostate cancer diagnosed?
As prostate cancer is asymptomatic initially, the only way to identify prostate cancer at an early stage is through screening.
The two tests that are commonly used to find prostate cancers early are a blood test to measure the level of prostate-specific antigen (PSA), and digital rectal examination (when a doctor examines the prostate by feeling it with a finger inserted in the rectum). Neither of these tests is 100% accurate. False positive and false negative results can occur for both of these.
However, if the PSA test is elevated then this may be an indication of underlying prostate cancer. But it is important to realise that many other conditions affecting the prostate can also cause an elevation in the PSA including benign prostate enlargement and infection.
If the GP is concerned by a rise in the PSA or if there is a suspicious lump on the prostate with the finger test then the patient is referred to a urologist where often a biopsy of the prostate is performed. A biopsy involves putting small needles into the prostate to collect tissue for pathological assessment. This is the only way to make a definitive diagnosis of prostate cancer and is necessary to determine how aggressive the tumour is which in turn is important for guiding further management. Although a fairly simple procedure, a biopsy is not without small risks such as bleeding, infection and urinary retention, so more and more urologists are performing MRI scans of the prostate before the biopsy to help determine whether a biopsy is really necessary, and if so to help target specific areas in the prostate that are more likely to harbour cancer. But an MRI is not absolutely necessary, and does cost the patient between $500 and $700. But in addition to helping with the biopsy, an MRI may also be used to tailor a patient’s surgery if they are found to have cancer that requires treatment and so I try and encourage an MRI in most of my patients.
Should all men be screened for prostate cancer?
Screening for prostate cancer remains one of the most controversial areas in men’s health today. Although screening is the only way to identify prostate cancer whilst it is curable, there can be detrimental effects of screening and so should be undertaken only after a patient has had an opportunity to weigh up the pros and cons of testing.
Also, PSA testing should not be offered to men who are unlikely to live for another 7 years (e.g. a man who already has another serious illness). These men are more likely to die of other causes even if they are harbouring intermediate or high risk prostate cancer.
But for generally healthy men, there is no doubt that screening for prostate cancer saves lives. The largest randomised study on PSA screening published in the Lancet found a 27% reduction in prostate cancer mortality after 13 years follow up in men who were offered screening. In a subgroup analysis of this study from the Swedish City of Gothenburg, which had a longer follow up of 18 years, there was an even larger reduction in prostate cancer mortality by 42%.
These randomised studies have demonstrated a benefit when men are screened between the age of 50 and 75, so I recommend screening with a PSA test every 1 to 2 years starting at age 50.
However, genetics has a significant impact on the likelihood of developing prostate cancer as well as on the age of onset. Men whose fathers were diagnosed with prostate cancer are approximately twice as likely to die from prostate cancer. That risk is 3 times higher for men with a father and a brother diagnosed with prostate cancer.
So importantly, if there is a strong family history of prostate cancer (especially a first degree relative) then screening should start at the age of 40.
Is there any downside to screening?
The main downside of screening is the diagnosis of clinically insignificant cancer. Unfortunately, this over-diagnosis is inevitable as testing for early cancer will also bring to light some cancers that would otherwise never have become clinically evident in the patient’s lifetime. From a histopathological point of view, these are real cancers but they are either progressing slowly or not at all, such that, if left, they would have never bothered the patient.
Balancing the known benefits and risks of PSA screening is difficult and is significantly influenced by personal values. As such, the decision of whether or not to undergo prostate cancer screening is an individualised decision.
Yet it remains that prostate cancer kills men. So, identifying and treating men with lethal cancers while avoiding over-diagnosis and over-treatment remains a significant challenge.
What treatment options are available for men diagnosed with prostate cancer?
It is very important to recognise that not all prostate cancers are lethal, and that many men will be diagnosed with indolent, slow growing tumours. A recent study called the ProtecT trial from the UK published in the New England Journal of Medicine demonstrated that for patients with the lowest grade of prostate cancer, also called Gleason 6, that the mortality rate from prostate cancer in the first 10 years is only 1% and importantly there was no difference in mortality between patients who had surgery, or radiotherapy and those that had no definitive treatment and were monitored very carefully, something called active surveillance.
Active surveillance involves PSA tests every 3 months, rectal examination every 6 months, biopsies from time to time, and (in specialised centres) multi-parametric MRI. If the cancer shows signs of growing, men can have surgery or radiotherapy. In general, men with low-risk prostate cancer who choose this option instead of immediate prostate cancer treatment do not have a higher risk of dying from prostate cancer within the next 10 years. For men younger than 60 years, choosing active surveillance might just delay surgery or radiotherapy rather than avoid it.
It is generally accepted among urologists and radiation oncologists that men with a small amount of low grade prostate cancer do not require any immediate treatment.
However, for those with Intermediate or high risk prostate cancer which are men with Gleason scores of 7 or higher, we would generally recommend some form of curative treatment, either surgery or radiotherapy.
The decision between radiation and surgery is also quite controversial and the patient should ideally be informed regarding the pros and cons of each of these treatment modalities and have the chance to discuss both options with a urologist and a radiation oncologist.
There have been significant advancements in both surgical treatments and radiation therapies for prostate cancer over the last decade. More recently robotic technology is being utilised to allow removal of the prostate in a minimally invasive approach, also known as keyhole surgery. Having this keyhole approach has the advantage of improving recovery following surgery, reducing pain and minimising post-operative complications. However, more important than the surgical approach is to choose a surgeon who is very experienced (whether in open or robotic surgery) and has good outcomes so that complications such as incontinence and loss of potency are minimised and the cancer outcomes are optimised.