Bisphosphonates are drugs that help prevent or slow down bone thinning (osteoporosis). They can help to treat some types of cancer that cause bone damage.

You might hear bisphosphonates called bone hardening or bone strengthening treatment. They are also a treatment for high levels of calcium in your blood. 

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 (secondary bone cancer).

The most common types are myeloma, breast cancer, prostate cancer and lung cancer.

Some types of cancer treatment can also affect the bones making them weaker, this includes chemotherapy and hormone therapies. 

How cancer affects 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
• constipation
• feeling sick
• feeling drowsy
• abdominal or bone pain

Bisphosphonate treatment can stop some types of cancer from spreading into the bone for some people. Studies have also shown that bisphosphonates can help some people with myeloma, secondary breast cancer and secondary prostate cancer to live longer.

Bisphosphonates might help to:

• prevent or control bone thinning (osteoporosis)
• reduce the risk of bones breaking
• reduce the level of calcium in your blood
• reduce pain

Types of bisphosphonate

There are several different types of bisphosphonate, including:

• disodium pamidronate (Aredia)
• ibandronic acid or ibandronate (Bondronat)
• sodium clodronate (Bonefos, Clasteon, Loron)
• zoledronic acid or zoledronate (Zometa)

You can have clodronate (Bonefos, Clasteon, Loron) as tablets or capsules. You have ibandronate (Bondronat) as a drip into your bloodstream (infusion) or as tablets. And you have zoledronic acid (Zometa) and pamidronate (Aredia) as a drip into your bloodstream. 

Most of the research so far has looked at using bisphosphonates with 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. 

There might sometimes be a choice of bisphosphonates for your type of cancer. Your doctor will give you the bisphosphonate best suited to your medical and practical needs. For example, you might prefer to take a bisphosphonate tablet at home rather than travel to hospital every month for treatment by drip.