Prostate Cancer

Original article by Tom Leach | Last updated on 27/6/2014
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Introduction

  • By the age of 80, >80% of men have prostate cancer
  • It is the second most common cancer in men, and the 4th most common cause of death for men in England and Wales.
  • Rates of prostate cancer are particularly low in Asians, and particularly high in African Americans and Scandinavians.
  • The tumours are adenomas and are usually located in the peripheral prostate.
  • Spread is most commonly to bones. And prostate cancer is unusual in that it often causes an increased bone density- osteosclerosis (most cancers cause decreased bone density).
  • Prostate cancer is also unusual because morbidity and mortality when diagnosed with the disease are not affected by age.
 

Aetiology

  • Prostate cancer is rare before the age of 40, and prevalence increases with age.
  • There is also a genetic factor – similar to that in breast cancer, so if someone in your family has the disease, then you are also more likely to have it.
  • Average life-expectancy after diagnosis is approximately 5-10 years – the disease is very slow to progress.
 

Clinical features

  • Lower UT obstruction
  • Nocturia
  • Poor flow of urine
  • Symptoms of metastatic spread – particularly to the bones (weight loss and bony pain)
  • Irregular hard prostate on DRE
 

Screening programs

  • These are controversial. Treatment of asymptomatic patients will result in serious morbidity (such as incontinence and sexual dysfunction) and there is no evidence that it improves overall outcome. There is no screening program in the UK, but there is in the USA.
 

Investigations

  • PSA – this likely to be markedly raised in metastatic disease (>16µg/dl). You can also have a normal PSA and still have prostate cancer.
  • DRE – it is NOT true that this elevates PSA levels
  • Transrectal ultrasound of prostate (TRUS), often with biopsy. The ultrasound is useful because it gives a more accurate estimation of size than a DRE, and can also help stage any tumour present. You may also want to examine the upper renal tracts for signs of dilation.
  • 10-15% of TURP surgeries will uncover a cancer when it is only suspected to be BPH.
  • Bone metastasis can be seen on X-ray as osteoscleoritc lesions.
 

Spread

  • Bones – particularly the axial skeleton– these are detected with radionuclide bone scans
  • Lymph nodes (obturator, internal iliac and presacral nodes)
  • Bladder
  • Rectum
  • Seminal vesicles
  • The scale for assessing the aggressiveness of the tumour is the Gleason score. This is a scale from 1-10, with 10 being the most aggressive cancers.
  • For cancer spread, the scale of T1-4 is used.
 

Treatment

The condition is only treatable when confined to the prostate.
  • Finasteride – a 5α-reductase drug, this may be given prophilactically to at risk patients to reduce the risk of developing cancer. It inhibits the production of dihydrotestosterone from testosterone and thus prevents growth of the prostate, however there is a high risk of sexual dysfunction.
  • Watching and waitng – this is the management method proposed by most clinicians. The side effects of potential treatments are numerous and debilitating, and thus treatments are usually held back fro as long as possible
  • Radical prostatectomy – the is total removal of the prostate. It can be done ‘open’ or laparoscopically. The cure rate is 90% for tumours confined to the prostate. At 12 months, the incontinence rate is 7%, and impotence rate is 30%. Operative mortality is higher in elderly patients, but overall is roughly 05%. Other side effects include DVT, lymphocoele and urethral stricture.
    • This is generally recommended for patients with a greater than 10 year life expectancy
    • After treatment the PSA level is monitored. It should reduce to almost 0 after a radical prostatectomy. If it does not, this is a sign that the cancer has metastasised.
    • Studies measuring the effectiveness of surgery as opposed to that of ‘watching and waiting’ found that surgery did reduce mortality from prostate cancer, but that overall, mortality was not affected (i.e. patients still died of something else – and so overall survival was not increased)
  • Radiotherapy – this, along with prostatectomy are the only curative treatments for prostate cancer. This is more suitable for elderly patients, although many younger and generally fit patient may chose it as an alternative to surgery. There are two types of this treatment:
    • External beam radiotherapy – this uses high energy x-rays from outside the body. There is a risk of impotence and proctitis, sometimes with rectal bleeding and soiling that requires surgery to correct.
    • You may also give androgen suppression therapy along with this treatment as an adjuvant, and this has been shown to boost intermediate outcomes.
    • Brachytherapy – this is where radioactive ‘seeds’ are planted in the prostate. The benefit of this is that the radiation cannot escape the prostate, and thus the systemic side effects are reduced. There are two types of brachytherapy:
    • Temporary high dose seeds -these tend to be used for patients with a more advanced prostate cancer, as they deliver a high dose of radiation. This may be used in conjunction with external beam radiotherapy.
    • Permanent low dose seeds – this is effective in early prostate cancer.
    • The brachytherapy treatments have a lower chance of developing erectile dysfunction, and problems voiding. Whilst these problems may still develop in some patients, often they correct themselves in the long term.
  • Androgen suppression – this is the main treatment for non-localised disease. About 80% of patients will show a sustained response to this treatment, but it can take 24-36 months for the response to appear. The quicker the PSA returns to the normal range, the better the prognosis. This treatment can take several forms:
    • Androgen suppression drugs
    • Luteinising hormone releasing hormone antagonists – these stop the release of lutenising hormone, and thus the production of testosterone.
    • Castration – many men refuse this treatment method.
  • Non-hormonal chemotherapy is not usually helpful.