Marker for breast cancer recurrence identified

August 26, 2006

Led by Dr. Amy Lee, professor of biochemistry and molecular biology in the Keck School of Medicine of the University of Southern California, the researchers have isolated a gene that some breast tumors produce at high levels, which protects the tumor from a common chemotherapy regimen. The 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 said in a prepared statement. "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 a protein, called GRP78. Review of the samples under a microscope showed that 67 percent of the tumors tested had high levels of GRP78.

Subsequent analysis of the patients' records showed that women whose tumors had higher levels of GRP78 were more likely to have had the cancer recur. That was particularly likely if the women received Adriamycin-based chemotherapy and no further treatment with the chemotherapy drug taxane, regardless of their tumor stage.

Likewise, women who had mastectomies followed by Adriamycin-based therapy were more likely to have the cancer return if their tumors had elevated levels of GRP78, compared to identically treated patients with low level of GRP78.

Conversely, the study also suggests that women who received Adriamycin-based therapy followed by additional treatment with taxane had a lower risk of cancer recurrence if their tumors had elevated levels of GRP78.

Lee hopes others will confirm her findings in subsequent research, and that it will eventually lead to a standard laboratory test that can screen all women diagnosed with breast cancer. "GRP78 will be one more bio-marker to help us offer designer medicine - treatments that are tailored to the patient's cancer instead of one-size-fits-all," Lee says.

The study is anticipated to have broad implications since other types of cancers have also been found to have elevated levels of GRP78. To that end, Lee is also collaborating with USC/Norris pathologist Richard Cote, M.D., on a study of the protein's role in prostate cancer.

Source: cancerfacts.com

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