About half of women whose breast cancer is treated with standard chemotherapy have their cancer return within five years. Most chemotherapeutic drugs have undesirable side effects, but there has been no way to predict who would benefit and who wouldn't. Fortunately, new research findings at the University of Southern California could change that.
Researchers at the USC/Norris Comprehensive Cancer Center have discovered a new biological marker in tumors that can help indicate whether a woman's breast cancer will respond to the most commonly prescribed chemotherapy drugs.
Amy S. Lee, Ph.D., professor of biochemistry and molecular biology in the Keck School of Medicine of the University of Southern California, isolated the gene for the GRP78 protein (78-kDA glucose-regulated protein) in 1980. It normally helps protect cells from dying, particularly when they are under stress from a lack of glucose. In her current research, Lee finds that breast cancer tumors with high levels of GRP78 are protected from a common chemotherapy regimen based on Adriamycin, a topoisomerase inhibitor. Her findings are published as a "Priority Report" in the August 15 issue of Cancer Research.
"The importance of this study is in its potential to help clinicians who treat cancer," Lee says. "It will help sort out the patients who won't respond to particular treatment regimens and will have a higher chance of cancer recurrence."
Lee and her colleagues analyzed records of 432 women with Stage II or III breast cancer treated at the USC/Norris Cancer Hospital, of whom 209 received Adriamycin-based chemotherapy. Tumor samples were collected from 127 of the women before they received chemotherapy. The samples were analyzed using antibodies to detect and stain GRP78 protein. Review of the samples under a microscope showed that two-thirds (67 percent) of the tumors tested had high levels of GRP78.