Women who have secondary breast cancer affecting their bones may be treated with a group of drugs called bisphosphonates. Secondary cancer in a bone can cause it to become weakened. Bisphosphonates help to strengthen the bones and reduce the risk of fractures or breaks. The drugs can also help to relieve bone pain and may reduce the need for radiotherapy.

Cancer in the bones can cause calcium to be lost from the bone and seep into the bloodstream. This is called hypercalcaemia and can cause symptoms such as feeling sick, tiredness and sometimes confusion. Bisphosphonates can help to reduce the amount of calcium in the blood and relieve symptoms of hypercalcaemia.

Bisphosphonates can be given as tablets that are usually taken once or twice a day, or by drip (infusion) over a couple of hours as an outpatient. The main bisphosphonates used to treat secondary breast cancer are:

• Clodronate (Bonefos®, Loron®), which is a tablet that is taken once or twice a day.
• Pamidronate (Aredia®), which is given as a drip lasting about an hour, every 3–4 weeks.
• Zoledronic acid (Zometa®), which is given as a drip lasting about 15 minutes, once a month.
• Ibandronate (Bondronat®), which can be given as a tablet once a day, or as a drip given over 15 minutes, every 3–4 weeks.

Side effects of bisphosphonates

Side effects are generally mild, but can include sickness (nausea), headaches, and flu-like symptoms such as chills and muscle aches. Bisphosphonate tablets can sometimes cause diarrhoea, constipation and heartburn. When given by a drip (infusion) the side effects can include a temporary increase in bone pain, known as tumour flare. If this happens your doctor can prescribe painkillers until the side effect wears off.

Very rarely bisphosphonates can cause jaw problems, so it is important to let your dentist know if you are being treated with bisphosphonates. You should also tell your doctor if you develop any problems with your teeth.

Bisphosphonates are usually given for as long as they are working. If the bisphosphonate is given to reduce high levels of calcium it may only be given when it’s needed.