Carcinoma of the prostate

Prostatic carcinoma is a disease of ageing. It is rarely discovered under the age of 50 and has a peak incidence in the 70s. It is rapidly becoming the most common malignancy to affect men.

Pathological features:

The tumour is an adenocarcinoma usually arising in the periphery of the prostate and confined within the Prostatic capsule. Its spread is:

• Local in the periprostatic and perirectal soft tissues and upwards into the pelvis
• Lymphatic to the iliac and para-aortic nodes
• Blood-borne, principally to bone

Symptoms:

• Bladder outflow obstruction
• Metastatic disease:
• Bone pain
• Leg swelling form lymphatic obstruction
• Renal failure from bilateral ureteric obstruction

Signs:

• A nodule in a palpably benign gland
• Hard, irregular prostate in rectal examination sometimes with perirectal and periprostatic thickening
• Ankle/leg oedema
• Other signs of metastases

Investigation:

A histological/cytological diagnosis must be made and can be achieved by:

• Transrectal or transperineal biopsy, preferably US guided
• Aspiration cytology
• Transurethral resection

Serum prostate-specific antigen (PSA):

• PSA is secreted in the serum by both benign and malignant prostatic tissue
• Its level correlates with the volume of prostatic tissue
• Not useful for screening but is useful for monitoring the progression of the disease and response to treatment

Abdominal ultrasonography:

• May identify unilateral or bilateral hydronephrosis because of ureteric involvement

Renal function tests

Serum ALP:

• Will be elevated in patients with bony metastases

Bone scanning:

• Radioisotope bone scans can detect areas of increased bone activity, irrespective of their cause

Staging:

T1a Incidental finding of tumour with low biological potential for aggressive behaviour in a prostate removed for clinically benign disease

T1b Incidental finding of tumour with potentially biological aggressive behaviour in a prostate removed for clinically benign disease

T1c Tumour identified because of elevated serum PSA

T2a Tumour involving half a lobe or less

T2b More than half a lobe but not both

T2c Both lobes

T3 Tumour extends through capsule and may involve seminal vesicle

T4 Tumour fixed to invasive adjacent structures other than seminal vesicle

Management options:

• No treatment with assessment of progress
• Endocrine therapy
• Radiotherapy
• Surgery

Endocrine therapy:

• Most of the proliferating cells of the prostate are dependent on testosterone
• 60-80% of patients with symptomatic prostate cancer respond to androgen suppression or ablation therapy
• The mean duration of response is 2 years
• Once the tumour is no longer hormone-sensitive, the mean survival is 6 months

Androgen suppression:

• LHRH analogues initially stimulate the pituitary but after ~7 days the pituitary receptors become blocked and down-regulation occurs
• Serum testosterone levels fall to castrate levels
• These drugs are long-acting and are administered sc every 1 or 3 months
• Due to the initial stimulation of the pituitary, an anti-androgen should be given for 7-14 days before the LHRH analogue is given to prevent disease progression

Androgen ablation:

• Is by bilateral subcapsular orchidectomy, which can be done under local anaesthesia as an outpatient
• There is no difference in response between orchidectomy and LHRH analogue therapy and the choice of treatment should lie with the patient

Radiotherapy:

Is effective in controlling the pain of bony metastases

It is also useful for the treatment of the primary if it is thought that the tumour is confined to the prostate

Surgical treatment:

Transurethral resection:

• Is used in patients who present with symptoms of outflow obstruction or acute retention

Radical prostatectomy:

• Controversial
• Only useful if the tumour is entirely confined to the prostate
• Mortality of ~1%
• Morbidity includes:
• Incontinence
• Erectile dysfunction
• Anastomotic strictures

Prognosis:

• In men with prostate cancer confined within the capsule who undergo radical prostatectomy, approximately 55% survive 10 years
• In comparison with those who have metastatic disease at presentation, of whom only 25% can be expected to survive 5 years