The cancer drug Avastin — taken with chemotherapy — prolongs the survival of women with breast cancers that have spread, new U.S. research indicates.

The study is published in Thursday's issue of the New England Journal of Medicine.

Avastin blocks the growth of blood vessels that supply cancer tumours, slowing the spread of metastatic disease.
(CBC)

Researchers from the Rush University Medical Center in Chicago studied 722 women whose cancer had metastasized or spread.

They found that Avastin (Bevacizumab) used in conjunction with chemotherapy doubled the time before the women's cancer symptoms returned — giving them an extra five months on average, compared with those who had solely received chemotherapy.

Those undergoing chemo alone saw their cancer return in six months versus 11.3 months for those on chemo and Avastin, the researchers said.

The drug also shrank cancer tumours by 50 per cent or more compared to chemotherapy alone, which shrank tumours by 25 per cent.

The findings stem from a clinical trial that assessed Avastin's effectiveness between December 2001 and May 2004.

"This therapy is a one-two punch. You hit the tumour with the chemo and sabotage new blood vessel growth by restricting its oxygen supply with Avastin," Dr. Melody Cobleigh, co-author of the study and director of the Coleman Foundation Comprehensive Breast Center at Rush University Medical Center, said in a release.

"This is a noteworthy advance in cancer treatment."

Avastin blocks the growth of blood vessels that supply cancer tumours, slowing the spread of metastatic disease. It was first used to treat colon cancer.