What’s New in Bone Cancer Research?

Many medical centers and other institutions around the world are conducting research on primary bone cancer.

The information here focuses on primary bone cancers (cancers that start in bones) that most often are seen in adults. Information on Osteosarcoma, Ewing Tumors (Ewing sarcomas), and Bone Metastasis is covered separately.

Genetics of primary bone cancers

There has been progress in learning about the gene changes in bone cells that lead to different types of bone tumors. Learning more about these changes might lead to better ways to find bone tumors, tell the different types apart, and treat them, based on their gene defects.

Treatment

Primary bone cancers are rare in adults, so it’s been hard to study the best ways to treat them. Most experts agree that people with primary bone cancers, especially those with advanced or recurrent cancers, might want to consider enrolling in a clinical trial studying new ways to treat these cancers.

There are many clinical trials focusing on treating different types of bone cancer.

Chemotherapy

Some studies are testing new chemotherapy (chemo) drugs. Researchers are also looking for new, and maybe better, ways to use the drugs already available. For instance, doctors are studying whether adding a bisphosphonate called zoledronic acid (Zometa) to the bone cement used to fill in the space left after removing a giant cell tumor might decrease the chance that the tumor will come back in that place.

Another area of interest is long-term chemo side effects. Some types of bone cancer can also occur among younger people, and doctors are trying to learn more about how the chemo drugs used might cause long-term side effects as survivors grow older.

Targeted drug therapy

Unfortunately, chemo isn’t very effective against some type of bone tumors. Newer targeted therapy drugs work differently from standard chemo drugs. They target certain changes in genes and proteins in cancer cells.

A great deal of research is being done to learn more about the genetic changes inside bone cancer cells. Doctors are using what they learn to develop new targeted drugs for some types of bone cancer, as well as to test and use existing targeted drugs that focus on some of these gene changes. These drugs might change the cancer's ability to grow and spread, providing newer and better ways to treat these tumors.

For instance, targeted drugs already exist for several gene and protein changes researchers have found in chordoma cells. Some of these targeted drugs are now options in treating advanced chordomas. Some targeted drugs are now being tested and used against advanced chondrosarcomas as well.

Immunotherapy

Immunotherapy drugs help the body’s own immune system to recognize and attack cancer cells. There are many types of immunotherapy medicines. Some of these are being studied to see if they can be helpful in treating certain types of bone cancers.

For example, cancer cells sometimes have even more gene and protein changes than typical cancer cells. This makes them even more different from normal cells (and therefore more visible to the immune system). Cancers with these types of changes are more likely to respond to some types of immunotherapy drugs. This includes cancers with high microsatellite instability (MSI-H), with defects in mismatch repair genes (dMMR), or with a high tumor mutational burden (TMB-H). Lab tests of tumor samples can be done to look for these changes.

Unfortunately, only a small proportion of bone cancers have these types of changes. But when they do, immunotherapy drugs called checkpoint inhibitors, such as pembrolizumab (Keytruda), can sometimes be helpful.

Researchers are also studying many other types of immunotherapy for use in treating bone cancers.

Drugs that affect bone cells

Drugs that affect the cells within bones (osteoblasts and osteoclasts) can be helpful in treating some bone tumors. These drugs are more often used for other types of cancer that have spread to the bones, but they might also be helpful in treating some types of primary bone cancers.

For example, denosumab (Xgeva) is a type of drug known as a RANKL inhibitor, which affects bone cells called osteoclasts. It can be used to treat some giant cell tumors of bone.

Zoledronic acid (Zometa) is a type of drug known as a bisphosphonate, which affects osteoclasts in a different way. Doctors are studying whether this drug also might be helpful in treating some types of bone tumors, such as giant cell tumors of bone.

Radiation therapy

The most common type of radiation therapy to treat most types of cancer uses beams of x-rays. But high doses of x-rays are needed to treat most types of bone tumors, which can affect nearby areas and lead to side effects. Doctors are now looking to other types of radiation that might be safer or more effective.

For example, proton beam radiation uses beams made up of protons (parts of atoms), which have properties that allow areas near the tumor to get less radiation. Proton radiation is often used to treat bone tumors near very sensitive organs, like the brain or the spine. It is sometimes used for tumors in other parts of the body, too. And as advances make this treatment even more precise and more widely available, it may be found to work better in treating bone tumors. There are only a limited number of proton beam treatment centers in the United States at this time.

A much less common form of particle radiation, carbon ion radiation, uses heavier particles that might cause more damage to the tumor. This may be helpful in treating some types of bone tumors that do not respond to current treatments, but more research is needed to be sure. This treatment is only available in a handful of centers worldwide, and there are no carbon ion radiation facilities in the United States at this time.