New Medicines That Slow Cancer’s Growth Don’t Seem to Improve Survival

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A number of studies measuring the benefits of experimental treatments for advanced-stage breast cancer have found that the experimental treatments improved progression-free survival but not overall survival compared to a standard treatment or placebo (sugar pill).

Progression-free survival is living without the cancer growing or spreading. So better progression-free survival in the studies mentioned above means women with advanced-stage breast cancer who got the experimental treatment lived longer without the cancer growing or spreading compared to women who got the standard treatment or placebo.

Overall survival is living, whether or not the cancer grows. So better overall survival in the studies mentioned above means women with advanced-stage breast cancer who got the experimental treatment lived longer, whether or not the cancer grew, compared to women who got the standard treatment or placebo.

Some doctors feel that better progression-free survival suggests that an experimental treatment can help treat advanced-stage breast cancer. Many other doctors feel that if overall survival isn't better (even if progression-free survival is better) the experimental treatment isn't a good option for advanced-stage breast cancer.

To help answer the question, researchers combined the results of 14 studies looking at various experimental treatments for advanced-stage breast cancer. Combining results like this is called a pooled analysis.

The research was published in the Journal of Clinical Oncology and presented at the 2011 annual meeting of the American Society of Clinical Oncology (ASCO).

The pooled analysis didn't really find a link between progression-free survival and overall survival. This suggests that if a study shows that an experimental advanced-stage breast cancer treatment improved progression-free survival but not overall survival, overall survival wouldn't improve if the study went longer.

The results could affect how the U.S. Food and Drug Administration (FDA) and other agencies like it around the world approve new medicines. The FDA is sometimes asked to approve a treatment for advanced-stage breast cancer based on research showing better progression-free survival, but not better overall survival.

For example, in December 2010 the FDA recommended removing the indication for the targeted therapy Avastin (chemical name: bevacizumab) in combination with the chemotherapy medicine Taxol (chemical name: paclitaxel) to treat metastatic, HER2-negative breast cancer that hasn't been treated with chemotherapy. This FDA recommendation was partly based on results from the RIBBON-1 study that showed women diagnosed with metastatic breast cancer who got Avastin in combination with one of three standard chemotherapy regimens had somewhat better progression-free survival (living 1 to 3 months longer without the cancer growing) but NOT better overall survival compared to women who only got chemotherapy.

In early 2011 the National Institute for Health and Clinical Excellence (NICE), the British agency similar to the FDA, also decided not to approve using Avastin to treat metastatic breast cancer. Still, the European Medicines Agency (EMA), a European agency similar to the FDA, has approved using Avastin in combination with Taxol to treat certain metastatic breast cancers.

The FDA recommendation on Avastin has been controversial. Removing the breast cancer indication from Avastin will be a process. The medicine itself is not being removed from the market and the FDA recommendation doesn't have any immediate effect on using Avastin to treat breast cancer. Genentech, the company that makes Avastin, has asked for a full FDA hearing to again present available research results on Avastin and to review plans for future research that could help both the FDA and doctors better understand who would most benefit from Avastin to treat advanced-stage breast cancer. Some of the discussion will probably focus on whether better progression-free survival without better overall survival is a good reason to keep or remove the breast cancer indication for Avastin.

Stay tuned to Breastcancer.org Research News for updates on the FDA Avastin hearings.

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