Roughly 1:6 men in the UK will develop prostate cancer (there are 35,000 new cases diagnosed each year) and 1:35 men will die of it (there are 10,000 deaths a year from prostate cancer in the UK, which equates to roughly one man every hour). Prostate cancer usually grows slowly and if present in a man with a life-expectancy of at least 10 years should be identified as early as possible to maximise the probability of cure or at least management by active surveillance.
Causes of prostate cancer
Genetic studies suggest that 40% of cases of prostate cancer are familial and are due to the inheritance of faulty or absent tumour suppressor genes. Migration studies suggest that the strongest influence, however, is the Western diet which is relatively rich in saturated fat (red meat and dairy products) and deficient in fruit and vegetables, which contain a variety of naturally-occurring anti-cancer compounds.
Prognosis
The long-term outlook for prostate cancer, whether treated or not, depends on the PSA at diagnosis, its aggressiveness or grade and its extent or stage.
(a) PSA at diagnosis
Lower PSA levels are generally associated with a better prognosis but there are two caveats: 20% of all prostate cancers occur with a normal PSA; and aggressive (Gleason 8-10) prostate cancer cells are sometimes so abnormal that they do not make enough PSA to trigger an abnormal blood test.
(b) the Gleason grade
The tumour is graded from 2-10 according to the microscopic appearance of the cancer cells. This appearance predicts the aggressiveness of the cancer. The higher the score, the more aggressive the tumour.
Survival from prostate cancer at 10 years based on the outcome of 59,876 patients (Lu-Yao, 1997).
Aggressiveness |
Gleason Score |
Surgery |
Radiotherapy |
Watchful Waiting |
Low |
2 - 4 |
94% |
90% |
93% |
Moderate |
5 - 7 |
87% |
76% |
77% |
High |
8 - 10 |
67% |
53% |
45% |
The notion of not being able to distinguish the ‘tigers’ from the ‘pussycats’ in relation to prostate cancer is untrue. For most patients with prostate cancer the need to intervene or not is clear.
However, although the Gleason grade gives an accurate prediction of aggressiveness of a prostate cancer, sampling error sometimes means that biopsies are not representative of the whole cancer.
(c) stage
This is described by the TNM (tumour, node, metastasis) system.
T1a: tumor found incidentally in less than 5% of prostate tissue resected during TURP
T1b:tumor found incidentally in more than 5% of prostate tissue resected during TURP
T1c: tumor found by needle biopsy froma normal-feeling prostate
T2a: tumor felt to occcupy half or less than half of one lobe
T2b: tumor felt to occcupy more than half of one lobe
T2c: tumor felt to occupy both lobes
T3a: tumor penetrating the capsule of the prostate
T3b: tumor invading one or both seminal vesicles
T4: tumor invades nearby structures, such as the bladder or rectum
N0: no spread to regional lymph nodes
N1: spread to regional lymph nodes
M0: no distant metastasis
M1a: spread to distant lymph nodes
M1b: spread to bone
M1c: spread to other sites
d'Amico risk categories for prostate cancer
Patients are commonly assigned to a risk category depending on their PSA, Gleason grade and stage. This helps to define the management options available. For instance, active surveillance is suitable for low- but not generally for intermediate- or high-risk patients.
| |
low |
intermediate |
high |
| PSA |
≤10 |
10-20 |
≥20 |
| Gleason grade |
≤6 |
7 |
≥8 |
| Stage |
T1-2a |
T2b |
≥T2c |
