Bisphosphonates are drugs that can help to strengthen bones and reduce the risk of bones breaking. You might have bisphosphonates to:
- help to prevent or slow down bone thinning (osteoporosis)
- treat a high level of calcium in the blood (hypercalcaemia)
- reduce pain from cancer that has spread to the bone
- treat some types of cancer that cause bone damage
You have bisphosphonates either as tablets or as a drip (infusion) into a vein in your arm.
Another drug called denosumab is a bone targeted treatment. It’s a type of targeted therapy called a monoclonal antibody.
Cancers that can affect bones
Most cancers that affect bones are ones that have started in another part of the body and have spread to the bone. This is called secondary bone cancer. The most common types of cancer that spread to the bone are breast, prostate and lung cancer.
Myeloma develops from cells in the bone marrow called plasma cells. Bone marrow is the spongy tissue found inside the inner part of some of our large bones.
Some types of cancer treatment can also affect the bones making them weaker.
How does cancer affect bones?
Cancers that spread to the bones damage the bones as they grow. The cancer cells that have spread into the bones also release proteins that interfere with the normal bone shaping process. These proteins are cytokines and growth factors.
The proteins stimulate the cells that break down bone (osteoclasts) and make them overactive. So, bone is destroyed faster than it's rebuilt.
This means your bones can become thinner and weaker, causing:
- pain in the affected bone
- high calcium levels in the blood
- an increased risk of breaks (fractures)
Calcium is normally stored in the bones and the breakdown of bone cells releases more calcium than usual into the blood.
Doctors call a high level of calcium in the blood hypercalcaemia. Symptoms of hypercalcaemia include:
- feeling thirsty
- feeling sick
- feeling drowsy
- abdominal pain
- bone pain
How do bisphosphonates work?
To understand how bisphosphonates work, it helps to know a bit about normal bone activity.
Normal bone activity
Your bones are made of living tissue, and are constantly changing. In healthy bones, specialised bone cells constantly break down and replace bone tissue.
These specialised bone cells are:
- osteoclasts, these cells break down old bone
- osteoblasts which build new bone
This process is called bone remodelling. There is a very good balance between the rates of bone breakdown and growth, which keeps bones strong and healthy.
Bisphosphonates are drugs that target areas of higher bone turnover. The osteoclast cells, which break down old bone, absorb the bisphosphonate drug. Their activity is slowed down. This reduces bone breakdown.
There are several different types of bisphosphonates, and they each work slightly differently. Doctors are still learning more about the exact ways in which bisphosphonates work.
We know that bisphosphonates can:
- interfere with the formation of osteoclasts
- make osteoclasts self destruct or die early
- change the signalling between osteoclasts and osteoblasts
- form a barrier between the bone and the osteoclast
Researchers have found that some types of bone targeted treatments can:
- prevent or slow down the activity of bone disease and improve symptoms in people with myeloma
- prevent or reduce bone problems, including for pain relief, in some people with advanced prostate cancer
- help reduce the rate of early breast cancer coming back in the bone for some postmenopausal women
- help some postmenopausal women with early breast cancer live longer
- help to prevent complications from other cancers that have spread to the bones
Cancer cells seem to be attracted to an environment where bones are being broken down. Researchers hope that stopping this process could slow cancer growth and help people live longer, as well as reduce bone damage.
Types of bisphosphonate
There are several different types of bisphosphonate, including:
- disodium pamidronate
- ibandronic acid or ibandronate (Bondronat)
- sodium clodronate (Clasteon, Loron)
- zoledronic acid or zoledronate (Zometa)
You can have sodium clodronate as tablets or capsules. You have ibandronic acid as a drip into your bloodstream (infusion) or as tablets. And you have zoledronic acid and disodium pamidronate as a drip into your bloodstream.
Most of the research so far has looked at using bisphosphonates in secondary breast cancer, secondary prostate cancer and myeloma. The type of bisphosphonate your doctor prescribes for you will depend on the type of cancer you have. You will have one that works for your type of cancer.
You might have bisphosphonate treatment if you have myeloma to:
- slow down or prevent bone disease
- treat the symptoms of myeloma such as bone pain or high levels of calcium
- treat myeloma if you have bone damage
This is usually:
- zoledronic acid
- disodium pamidronate, if you can’t have zoledronic acid for some reason
- sodium clodronate, if you can’t have zoledronic acid or disodium pamidronate for some reason
You might have bisphosphonate treatment if you’re having hormone therapy and have osteoporosis (thinning of the bones). If you can’t have bisphosphonates for any reason you might have denosumab.
Bisphosphonates are not recommended to try and prevent prostate cancer that hasn’t spread, spreading to the bone.
Advanced prostate cancer
You might have bisphosphonate treatment if you have advanced cancer and hormone treatment is no longer controlling your cancer. This aims to prevent or reduce problems with your bones. You are likely to have zoledronic acid.
You might have bisphosphonates as tablets or an injection into the vein for pain relief in one of the following situations:
- you have advanced cancer and hormone treatment is no longer controlling the cancer
- other treatments, including painkillers and radiotherapy, have not helped your pain enough
For some women, bisphosphonate treatment can help reduce the risk of their breast cancer spreading to the bones. And improve some women’s chance of surviving their cancer.
You might have bisphosphonate treatment alongside your cancer treatment if:
- you have early and locally advanced breast cancer, with cancer in the nearby lymph nodes
- and you are postmenopausal
Or you might have this treatment if all of the following apply:
- have locally advanced breast cancer, which isn’t in the nearby lymph nodes
- are postmenopausal
- are at high risk of your cancer coming back after treatment
For these women, the bisphosphonates recommended are:
- zoledronic acid into a vein, usually every 6 months given at the same time as chemotherapy, for 3 years
- sodium clodronate, as a tablet for 3 years – if you can’t have zoledronic acid for some reason
You might also have bisphosphonates if you:
- have breast cancer that has spread to the bones, to try and prevent any bone problems and reduce pain
- have, or are at high risk of, bone thinning (osteoporosis)