Bisphosphonates are a group of drugs that may be used by men with prostate cancer that has spread to the bones. Prostate cancer that has spread to the bones is not the same as bone cancer, which starts in the bones.
Why might I need to take bisphosphonates?
Bisphosphonates may benefit men with prostate cancer that has spread to the bones and is no longer responding to hormone therapy. They do not actually treat the cancer but they bind to areas of bone where there is a lot of damage and can help to relieve bone pain. They may also help to prevent and slow down the breakdown of bone. However, we do not yet have enough evidence to show whether they significantly reduce the risk of bone fractures. They also help prevent a rare condition called hypercalcaemia, where the amount of calcium in your blood increases. The causes of this are not fully understood. Symptoms of hypercalcaemia include thirst, drowsiness and sickness.
Trials continue to look at using bisphosphonates in men with prostate cancer and how it may help improve survival. Possible disadvantages of taking bisphosphonates may include:
• Side effects such as feeling sick, tiredness and flu-like symptoms.
• Having to make a trip to the hospital every three or four weeks for treatment. This can be tiring for many men especially if you live a long way from the hospital. If you have any problems speak to your specialist team.
• More research is needed before we will know which bisphosphonate drug is most effective at relieving pain. More research is also needed to find out if bisphosphonates are helpful in preventing bones breaking (fractures).
What does treatment with bisphosphonates involve?
There are several bisphosphonate drugs on the market. Your doctor may prescribe you other bisphosphonate drugs such as pamidronate (Aredia) instead of zoledronic acid. You may have pamidronate if you have high calcium levels in your blood or if you have had bad side effects from zoledronic acid. Your doctor will explain which drug they are recommending for you and why.
Zoledronic acid is usually given as an infusion into a vein every three to four weeks. An infusion involves running a fluid containing the drug through a fine tube called a cannula into a vein in your arm. This allows the drug to enter the blood stream and travel throughout the body. Treatment takes about 15 minutes. You will need to go to the hospital for each treatment. Positioning the cannula can sometimes feel uncomfortable when it goes in but it should not cause any pain once it is in.
What happens before I start treatment?
Before you start bisphosphonate treatment, it is important to tell your doctor if you have ever had any problems with your liver, kidneys, heart, teeth or jaw. Your doctor may also advise you to visit your dentist for a check up before your course of treatment starts. Before each treatment, drink plenty of water to stop you becoming dehydrated. Your doctor can give you advice on this.
If you are having long term treatment with bisphosphonates your doctor is likely to suggest that you take calcium and vitamin D supplements, particularly if you are having zoledronic acid or pamidronate. This is to make sure that you are getting enough calcium to build new bone. If blood tests show that you have high levels of calcium in your blood you will not need to take these supplements. Most men do not have any problems taking Vitamin D and calcium supplements but possible side effects of these include constipation, sickness (nausea and vomiting), stomach cramps, dry mouth, increased thirst and passing urine more often. Tell your doctor if you notice any possible side effects.
How do bisphosphonates work?
Healthy bones are constantly breaking down and rebuilding. This is how our bones stay strong. When prostate cancer spreads to the bone it can cause the bone tissue to break down too fast. Your bones cannot replace the bone tissue at the same rate and your bones may become weak and prone to breaking easily. Bisphosphonates work by binding to areas of bone which have been damaged.
Other treatments that can help with bone problems include:
• Palliative radiotherapy, either external beam or an injection of a radioactive substance (Strontium 89).
• Surgery to stabilise or fix the bone.
• Pain-relieving drugs, which can be used alone or in combination with the other treatments described above.
When deciding on a treatment, you will need to consider the risk of side effects and how effective the treatment is likely to be.
The advantages and disadvantages of bisphosphonate treatment
The advantages of taking bisphosphonates can include:
• Helping to relieve bone pain caused by the cancer spreading into your bones.
• Controlling and reducing high blood calcium levels which can cause serious side effects if left untreated.
• Many men may have a better quality of life due to less pain and being able.
What are the side effects?
Side effects will vary from person to person. They will also depend on which drug you are taking. The most common side effects with zoledronic acid and pamidronate are listed below. You may not get any or all of these. Your cancer may cause side effects even if you are not taking bisphosphonates.
Common side effects of bisphosphonates may include:
• An increase in bone pain when you first take the drugs.
• Flu-like symptoms such as joint and bone ache, raised temperature and weakness. These symptoms usually only last up to 24 hours after treatment. Tell your doctor if you have any of these symptoms.
• Feeling very tired (fatigue). Avoid driving home after treatment.
• Feeling or being sick (nausea and vomiting).
• A drop in the level of red blood cells (anaemia). This may make you look pale and feel weak.
Many of these side effects only last a few days. Your doctor or specialist nurse will be able to give you medicine to relieve the symptoms if necessary. Pain-relieving drugs can help with bone pain until it calms down.
There are some less common side effects that can happen if you take bisphosphonates. These include:
• Changes in how well your kidneys work. Your specialist team will do regular blood tests to check this.
• Lowered levels of calcium and other minerals in your body such as potassium and magnesium. Your doctor will keep a check on these by doing regular blood tests.
There is also a rare condition called osteonecrosis of the jaw that can develop if you take bisphosphonates for more than a year. This means that healthy bone underneath the teeth dies because of a poor blood supply to this area. This seems to happen more commonly in people who have been having dental treatment while they are taking bisphosphonates. If possible you should not have any dental Tell your doctor if you have any loose teeth, gum problems (pain, swelling, infections) or numbness or a heavy feeling in the jaw. Good oral hygiene is also important. Let your dentist know that you are taking bisphosphonates. You may wish to visit your dentist before starting bisphosphonate treatment to get any existing dental problems sorted out.