Avastin Doesn’t Affect Overall Survival in Metastatic Breast Cancer

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Avastin (chemical name: bevacizumab) is approved by the U.S. Food and Drug Administration to be used in combination with Taxol (chemical name: paclitaxel) to treat people with metastatic HER2-negative breast cancer who haven't yet received chemotherapy. Avastin also is used to treat advanced-stage lung, colon, and kidney cancer. Avastin is given intravenously.

Metastatic breast cancer is cancer that has spread outside the breast to another part of the body.

Two studies -- AVADO and RIBBON 2 -- suggest that treating metastatic breast cancer with Avastin and chemotherapy slightly increases the length of time women live without the cancer growing (called progression-free survival or PFS), but doesn't affect overall survival. These results were presented at the 2009 San Antonio Breast Cancer Symposium.

Avastin works by blocking the growth of new blood vessels that cancer cells depend on to grow and function. A protein called vascular endothelial growth factor (VEGF) makes new blood vessels grow in cancer cells. Avastin blocks the VEGF protein.

In the AVADO trial, women diagnosed with metastatic breast cancer got one of three treatments:

  • Taxotere (chemical name: docetaxel) alone
  • Taxotere plus a low dose of Avastin
  • Taxotere plus a high dose of Avastin

This was the first cancer treatment the women received (called first-line treatment by doctors). After about 2 years of follow-up, there were small differences in progression-free survival:

  • 10 months for women who got the high dose of Avastin and Taxotere
  • 9 months for women who got the low dose of Avastin and Taxotere
  • 8 months for women who got only Taxotere

Though small, the differences in progression-free survival were statistically significant, which means that the difference was likely the result of the different treatments and not because of chance. Still, overall survival was essentially the same -- between 30 and 32 months -- no matter which treatment a woman received.

In the RIBBON 2 trial, women diagnosed with metastatic breast cancer were treated with one of several chemotherapy medicines alone or combined with one of two Avastin doses, depending on which chemotherapy was used. All the women already had received some type of treatment for the metastatic cancer, so the treatments being studied are called second-line treatments. There were small differences in progression-free survival:

  • 7.2 months for women who got Avastin and chemotherapy
  • 5.1 months for women who got chemotherapy alone

The difference was statistically significant, which means that the difference was likely the result of the different treatments and not because of chance.

The results from both the AVADO and RIBBON 2 trials suggest that adding Avastin to chemotherapy to treat metastatic breast cancer can slightly increase the length of time a woman lives without the cancer growing. Still, adding Avastin to chemotherapy didn't increase the total amount of time a woman lived after treatment started compared to chemotherapy alone.

Based on these and other results, some doctors wonder if Avastin should be used routinely to treat metastatic breast cancer.

Some doctors are concerned that the benefits of Avastin don't outweigh the risk of side effects. Common side effects of Avastin include high blood pressure, nosebleeds, and extra protein in the urine. People treated with Avastin also may have weakness, pain, and diarrhea. Avastin also may cause other serious side effects, including a higher risk of stroke or heart problems, kidney malfunction, and reduced white blood cell count.

Other doctors worry that the small benefits of Avastin don't justify its high cost: $30,000 to $40,000 per month. Depending on the type of insurance they have, some people receiving Avastin may have to pay part of this cost.

If you've been diagnosed with metastatic breast cancer, you and your doctor will develop a treatment plan that will likely include chemotherapy and possibly hormonal therapy and/or targeted therapy medicines such as Avastin. No matter which treatments are recommended, ask your doctor about:

  • the reasons for each treatment recommendation (including any combinations)
  • treatment timing and sequence
  • the expected benefits, risks, and side effects of each treatment

With the most-up-to-date information, you and your doctor can decide on a treatment plan that makes the most sense for you and your unique situation.

You can learn more about Avastin, how it works, and how it is used to treat advanced-stage breast cancer in the Breastcancer.org Targeted Therapies section.

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