As scientists learn more exactly how cancer cells break off from a main tumor, spread through the blood and lymph circulation, and begin to grow in a new location, they come closer to the goal of developing treatments that can prevent bone metastases.

Radiopharmaceuticals

Newer drugs are being developed that have fewer side effects such as bone marrow damage. Use of radiopharmaceuticals is growing, and researchers are looking at new ways to deliver radioactive particles to cancer cells by attaching them to antibodies or certain chemicals.

Testing known drugs for new purposes

In animal models and lab tests, several known drugs that were designed for other uses have shown some action that might help slow or prevent bone metastases. Clinical trials have looked at some of these drugs, and although most have not shown promise in human trials to date, others are still being tested.

Bisphosphonates are being studied as a possible way to prevent bone metastases in high-risk patients, which is a new use for them. Also, researchers are learning more about when to start and how long to use bisphosphonates, and how to reduce their side effect risks.

New drugs to prevent and treat bone metastases

A medicine called denosumab that is being developed to treat osteoporosis is also being tested in several kinds of cancer to find out if it will slow the growth of bone metastases. The company will likely seek FDA approval to use it for osteoporosis by early 2009. Long term effects of the drug are not yet known, but it seems promising in early clinical trials.

Researchers are also learning that osteoclasts (the cells that break down bone) and osteoblasts (the cells that help build bone) contain other molecules that can be targeted. Some compounds are already being tested in animal models.

Although not as close to being developed, researchers are looking for drugs that block the action of cancer cells on bone. Cancer cells put out chemicals that cause bones to dissolve. There are also compounds that allow the cancer cells to stick to bone and grow there. Some of these chemicals have already been identified. It is hoped that new drugs can be made to block them without harming the rebuilding of normal bone.

New tests

A special kind of PET scan for bone uses radioactive fluoride instead of glucose. The fluoride is attracted to bone metastases better than glucose. It is especially useful with newer devices that combine a CT scan and a PET scan to even better pinpoint the tumor.

Studies are also being done on the types of substances released into the bloodstream when cancer cells start growing in bones. There is a chance that in the future, doctors will be able to know when cancer reaches the bones so that metastases can be treated before they cause serious damage. Such a test might also be useful to find out if treatment for bone metastases is working.

Last Medical Review: 01/13/2008
Last Revised: 05/13/2009