Bicalutamide (Casodex)

Prostate cancer depends on the male sex hormone, testosterone, to grow. The aim of hormone therapy for prostate cancer is to reduce or stop the body making testosterone, or to block testosterone from reaching the cancer. This can shrink the cancer or slow its growth.

Bicalutamide is a type of hormone therapy drug called an anti androgen. Androgens are male sex hormones, and testosterone is an androgen. Prostate cancer cells have receptors on them that take up testosterone. Anti androgens attach to these receptors and stop testosterone reaching the cancer cell. So bicalutamide blocks the testosterone that prostate cancer needs to grow.

You may take bicalutamide either on its own, or with another type of drug for prostate cancer called a luteinising hormone (LH) blocker. LH blockers include goserelin (Zoladex), leuprorelin (Prostap) and triptorelin. If you are having bicalutamide with one of these drugs, the aim is to stop what is called a flare reaction. When you first start treatment with LH blockers you actually make more testosterone for the first few days or weeks. This soon settles down, and after a few weeks you stop making testosterone. Bicalutamide helps reduce any cancer symptoms caused by the temporary increase in testosterone levels.

You take bicalutamide as a tablet, once a day. If you are having it to stop a flare reaction, you take it for a few days before starting the luteinising hormone blocker, and stay on it for about 4 to 6 weeks.

It is very important that you take tablets according to the instructions your doctor or pharmacist gives you. For example, whether you have a full or empty stomach can affect how much of a drug gets into your bloodstream. You should take the right dose, not more or less. And never stop taking a cancer drug without talking to your specialist first.

There is general information about hormone therapies in the cancer treatment section.

We've listed the side effects associated with bicalutamide below. You can use the links to find out more about each side effect. Where there is no link, you can go to the cancer drug side effects section or use the search box at the top of the page.

More than 10 in every 100 people have one or more of these.

• Breast tenderness and swelling – this can affect about 2 out of 5 men (40%) and can be distressing. If it is a problem for you, speak to your doctor and they can prescribe treatment to help it
• Hot flushes – these are similar to those that women have during the menopause and affect about 1 out of 2 men treated (50%). Unfortunately some men have them for as long as they stay on treatment. Tell your doctor or nurse if your hot flushes are difficult to cope with
• Pain – about 3 out of 10 men (30%) will have general body pain, 3 out of 20 men (15%) will have some back pain, and 1 out of 10 men (10%) will have some pain in their lower abdomen (pelvic pain)
• Decreased interest in having sex (low libido) affects most men
• A skin rash or dry skin and itching
• Loss of strength and energy
• Weight gain

Between 1 and 10 in every 100 people have one or more of these.

• Tiredness (fatigue) and weakness happens in about 1 in 10 men (10%) – this usually improves within a few weeks of starting treatment
• Constipation happens in about 1 in 10 men (10%)
• Low levels of red blood cells (anaemia) that may cause tiredness and breathlessness
• Feeling sick or being sick affects about 1 in 10 men (10%) – this is usually mild and can be controlled by anti sickness tablets
• Diarrhoea affects about 1 out of 10 men (10%) – it is usually mild but if you do get diarrhoea you should make sure you drink plenty of fluids
• Problems getting an erection (impotence) affect about 1 in 20 men (5%) – it usually improves after you finish treatment
• Changes in the way your liver works affect about 1 in 20 (5%) men taking bicalutamide – you will have blood tests to check for this. Some men need to stop taking the drug. The liver nearly always goes back to normal after treatment ends 
• Cough and breathlessness – this affects about 1 in 20 men (5%)
• Chest pain
• Heart problems – bicalutamide can affect the way the heart works in about 1 in 20 men (5%). This can cause an increase in blood pressure and swelling of the legs (oedema)
• Bicalutamide may have a harmful effect on a developing baby and you are advised not to father a child while you are having treatment. If you are sexually active you need to discuss contraception with your doctor or nurse before you start your treatment
• You may not be able to father a child immediately after treatment with bicalutamide but this is usually temporary. It is important to talk to your doctor about the possible effect on your fertility before starting treatment

Fewer than 1 in 100 people have these.

• Dizziness
• Difficulty in sleeping at night and very rarely, sleepiness during the day
• Flu like symptoms, fever, and chills
• Low mood – this usually improves within a few weeks of treatment. If it goes on for longer, talk to your doctor or nurse about getting some help

Bicalutamide can react with the drug warfarin. If you are taking warfarin you will need regular checks and your warfarin dose may need to be adjusted.

The side effects above may be mild or more severe. A side effect may get better or worse through your course of treatment. Or you may develop more side effects as the course goes on. This depends on

• How many times you've had the drug before
• Your general health
• The amount of the drug you have (the dose)
• Other drugs you are having

Talk to your doctor, pharmacist or nurse about all your side effects so that they can help you manage them. You should have a contact number for your treatment centre. You can ring if you have any questions or problems. They can give you advice or reassure you. If in doubt, call them.

Tell your doctor about any other medicines you are taking, including vitamins, herbal supplements and over the counter remedies – some drugs can react together.