Avastin is commonly prescribed for colon cancer that has spread ("metastatic" cancer) because the drug hinders the growth of new blood vessels that feed tumors.
With the yttrium-90 procedure, which has been in use at major U.S. medical centers for more than a decade, a catheter is inserted into a small incision near the groin and threaded through arteries until it reaches the hepatic artery in the liver, where millions of microbeads are released near tumor sites. These beads emit high-dose radiation directly to cancerous cells, sparing damage to healthy cells.
Goldin's team found that 40 percent of the 17 patients with shorter intervals -- less than three months -- since their last Avastin dose before receiving the microbeads needed their microbead infusion stopped early due to slow blood flow near the tumors, a much higher number than patients whose last Avastin dose was further in the past. This was expected, Goldin said, because the main effect of Avastin is to cut tumors' blood supply.
Additionally, treatment with Avastin didn't increase the survival benefit of the microbeads, which added 10 to 12 months to patients' life spans compared to chemotherapy alone, Goldin said -- a survival of 34.5 months after the diagnosis of metastatic colon cancer, compared with 24 months.
"If you look at those [survival] numbers, there's a promising benefit" to using microbead radiation, he said. But the cost of both treatments is high -- in the tens of thousands of dollars per patient, he noted.
Dr. Felice Schnoll-Sussman, a gastroenterologist and director of research at the Jay Monahan Center for Gastrointestinal Health at New York-Presbyterian Hospital/Weill Cornell Medical Center in New York
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