Prostate Cancer
With 19,233 men diagnosed in 2013, prostate cancer is the third most commonly diagnosed cancer in Australia and the most commonly diagnosed cancer in men.
The incidence of prostate cancer varies widely between ethnic populations and countries. The lowest incidence is reported in Asian countries with Tianjin, China having the lowest recorded rate at 1.9 per 100,000 per year. The highest rates are reported in Scandinavia and North America and especially among African-American men (137 per 100,000 per year). The incidence of prostate cancer is growing in most countries. One potential explanation for the rising incidence of prostate cancer may be the increased longevity of men in Western populations with decreased death rates from causes such as cardiovascular disease. However, it is also possible that simply more men are developing prostate cancer due to changes in many cultures such as the adoption of Western style diets high in animal fats as well as other, as yet, uncharacterised environmental factors. The median age of diagnosis with prostate cancer is 72 years with 70% of patients being diagnosed after the age of 65 years. Results from autopsy studies suggest that the majority of men over the age of 85 years harbour microscopic evidence of prostate cancer.
Prostate cancer was responsible for 3102 deaths in Australia in 2014.
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Age is the strongest risk factor for diagnosis of prostate cancer as the incidence of prostate cancer rises markedly with age. Less than 0.2% of patients diagnosed with PC are under 45 years while 70% are over 65 years.
Younger patients with prostate cancer do not appear to have more aggressive disease than older patients. However, because of their longer life expectancy, younger patients are more likely to develop symptoms and die of prostate cancer.
A family history of prostate cancer with at least a father or brother having prostate cancer leads to a 2-3 fold increased risk of being diagnosed with the disease. This risk increases with the number of affected relatives and with the decreased age of the individual.
The possibility of high risk genes such as BRCA2 have been reported.
Dietary factors, in particular diets high in fat, meat and dairy products have been associated with increased risk of prostate cancer. Higher consumption of red meat has been associated with PC risk. In particular, when cooked at high temperatures, red meat has previously been correlated with increased risk of colorectal, bladder and renal cancers. Conversely, higher dietary intake of phytoestrogens as found in soybeans, lycopene as found in tomato based products, selenium and vitamin E have been shown in some studies to be associated with decreased prostate cancer risk.
The natural history of prostate cancer is highly variable and longer on average than most other cancers. In patients with localised prostate cancer who are observed with no treatment, disease-specific survival is 70-80% at 10 years.
The widespread use of screening for prostate cancer has meant that more patients can be diagnosed with earlier stage disease than was previously possible. Currently blood PSA testing and digital rectal examination remain the mainstays of prostate cancer screening.
The use of PSA as a screening test has a number of limitations due to potential false positives caused by elevations related to patient age, prostate volume, prostatitis and prostate manipulation eg sexual activity or bike riding.
The serum PSA concentration is not in itself a diagnostic test for prostate cancer. The definitive test is still needle biopsy of the prostate via a transrectal or transperineal route. Prostate biopsies are accompanied by discomfort as well as risks including sepsis, bleeding, urinary retentio and blood in the semen.
Imaging modalities such as magnetic resonance imaging (MRI) are useful in the preoperative setting for detection of cancer and the determination of local extension of tumour. Imaging, which has been used in the detection of metastatic prostate cancer prior to treatment includes CT scan, MRI, bone scan and positron emission tomography (PET scanning).
The decision of how best to manage early prostate cancer is complex. A lack of conclusive evidence from randomised trials of different treatments is the main reason for this. Currently, patients and their doctors base their treatment choices on a combination of variably weighted disease factors such as PSA level, tumour grade and clinical stage with patient factors such as age, patient health, prostate size, presence of bladder outflow tract obstruction, erectile function and perceived value of sexual function. Information on decision making for patients with localised prostate cancer may be found in other sections of this website or by following the links to the websites listed below.
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