It is likely that your doctor was referring to a group of drugs known as bisphosphonates. These drugs are commonly used to treat breast cancer that has spread to the bones. Secondary breast cancers in the bone may cause very little in the way of symptoms, but if problems do develop then pain is the most likely symptom. However there are other possible complications. These include:

• an increased risk of fractures because the bone is weakened by the cancer

• an increased thirst, feelings of sickness, irritability and confusion caused by a raised calcium level in the blood which can sometimes happen if there are bone secondaries. The cancer can cause some of the calcium stored in the bones to be released into the blood stream leading to an excess of calcium in the blood (this is called hypercalcaemia)

• numbness and weakness in the legs or occasionally even paralysis, which can occur if the cancer is affecting the bones of the spine. The cancer can cause the bones of the spine to collapse or distort putting pressure on the nearby nerves. This is known as cord compression.

During the 1980s a group of drugs called bisphosphonates were found to help protect the bones against some of the effects of secondary cancer.

Clinical trials in women with breast cancer that has spread to the bones have shown that regular bisphosphonates reduce the risk of complications like fractures, hypercalcaemia and cord compression and probably help with pain control.

The two drugs that have been most widely studied in this way are clodronate (Loron® or Bonefos®), which is taken as a tablet, and pamidronate (Aredia®) which is given through a drip into a vein (intravenously). A new bisphosphonate called zoledronic acid (Zometa®) is also an intravenous treatment but has the advantage that it can be given over a few minutes rather than a few hours as with pamidronate.

Not all women who have secondary breast cancer in their bones will be treated with bisphosphonates. Some women prefer to avoid the side effects that these drugs can cause. Side effects are particularly a problem if oral bisphosphonates are used and can include nausea, sickness, diarrhoea and skin rashes. Fortunately, in practice most people have very few side effects. Some women also find that taking the drugs is very inconvenient as the drugs have to be taken regularly (with tablets several times a day or drips at least every few weeks) and continued long term.

Unfortunately the bisphosphonates are not cheap drugs and cost may also be an issue in their use. Because of these factors doctors tend to be selective in prescribing bisphosphonates and use them for those women who they feel are most likely to get a worthwhile benefit from treatment.