Cancer drugs and radiation target and kill fast-growing cancer cells. But a small number of noncancer cells in the tumor often survive. These, researchers believe, are “mother” cells — stem cells that shrug off treatment and survive to manufacture more cancer cells.
“Cancer stem cells are present, we believe, in all cancers,” said Dr. Jenny Chang, medical director of the breast center at Baylor College of Medicine. “So that 1 to 5 percent of the cancer contains cancer stem cells. And while chemotherapy kills 99 to 95 percent of the tumor, what’s left behind is the 5 percent of cancer stem cells. Those will then regrow and regenerate.”
Chang spoke at a press briefing on experimental new cancer drugs Friday at the 32nd annual San Antonio Breast Cancer Symposium , which continues through Sunday.