In some ways, anti-angiogenesis treatment is like chemotherapy. Both are forms of systemic treatment. This means that both treatments use drugs that travel throughout the body to have their effects. But anti-angiogenesis drugs do not work the same way chemotherapy does. Because of this, they differ in terms of what side effects they may cause and how well they work.

Side effects

For the most part, anti-angiogenesis drugs tend to have milder side effects than chemotherapy drugs.

Chemotherapy drugs work by attacking cells in the body that grow and divide quickly. This is why they work against cancer cells. But they can also harm other cells that divide quickly, such as those in the bone marrow, the skin, and in the mouth and intestines. This can lead to serious side effects like low blood cell counts (which can cause tiredness, infections, and bleeding), hair loss, mouth sores, nausea, and diarrhea.

Unlike chemotherapy drugs, anti-angiogenesis drugs do not harm these normal cells. They act where new blood vessels are forming, so they usually do not cause these kinds of side effects.

But anti-angiogenesis drugs are not risk-free and do have their own side effects. Although they're not as common or severe as those from chemotherapy, they can still be serious, or even life-threatening. Because anti-angiogenesis drugs are fairly new, it's not yet clear if the effects seen so far will be seen with all of these drugs.

Bleeding or holes in the digestive tract

Most anti-angiogenesis drugs have been shown to raise the risk of internal bleeding or of developing a hole in the digestive tract (stomach or intestines). In rare cases, this has been serious or even fatal. In people with a history of bleeding problems, with certain types of cancers, or with cancers in certain locations, the risks of using these drugs might outweigh the benefits.

Raised blood pressure

It's not clear why, but some of these drugs raise blood pressure. This problem is rarely serious and it seems to respond well to blood pressure medicines. Still, some people who have a history of high blood pressure, heart disease, or stroke may need to be watched closely or may not be able to take these drugs.

Surgery risks

Because they may affect wound healing, anti-angiogenesis drugs may need to be stopped before surgery or not started until a few weeks after surgery. This is to make sure blood vessels that are cut are able to repair themselves.

Pregnancy risks

These drugs might also affect a developing fetus. They will probably not be used for women who are pregnant or might become pregnant.

How anti-angiogenesis drugs affect tumors

Because chemotherapy and anti-angiogenesis drugs don't affect the same parts of the body, they can sometimes be given together.

When chemotherapy drugs work, they often cause tumors to shrink a lot, sometimes even making them disappear. But anti-angiogenesis drugs don't seem to work in the same way. In some cases they shrink tumors, but in others they just seem to stop them from growing any larger. (This is probably because the tumors have already grown some blood vessels.) Although this may help some people, it's not yet clear how long patients need to keep taking these drugs to keep the tumors from growing. Some patients may need long-term or maybe even life-long treatment.

Newer approaches that combine anti-angiogenesis drugs with chemotherapy, other targeted drugs, or radiation may work better than using them alone. For instance, early studies that tested the drug bevacizumab (Avastin) by itself did not find that it helped people with cancer to live longer. But later studies found that when it was used along with chemotherapy to treat certain cancers, it helped people live longer than if they got the chemotherapy alone.

Doctors aren't sure why this is the case. One theory is based on the fact that chemotherapy drugs may have a hard time getting to cells in the middle of tumors. Tumor blood vessels grow in a short amount of time and in an abnormal environment, so they are not as well-made and as stable as normal blood vessels. Because of this, they tend to be leaky. This affects how well drugs can reach the inside of the tumor. The theory is that bevacizumab may somehow stabilize these tumor blood vessels for a short period of time, allowing the chemotherapy to reach more tumor cells and be more effective. Research in this area is ongoing.

How well they work in different cancer types

Chemotherapy drugs can be useful in treating many types of cancer, but some cancers do not respond well to them. In some cases, anti-angiogenesis drugs may prove to be a better option.

For example, chemotherapy isn't helpful against kidney cancer. But doctors have long known that kidney tumors tend to form many blood vessels. Anti-angiogenesis drugs, such as sunitinib (Sutent) and sorafenib (Nexavar), have been shown to be useful against this type of cancer. Many doctors now consider these drugs to be the best treatments when systemic therapy is needed.

Because of the way anti-angiogenesis drugs work, they are only useful in treating cancers that form tumors. They won't work against blood cancers like leukemias.

Last Medical Review: 03/10/2009
Last Revised: 03/10/2009

Back to Anti-Angiogenesis Treatment