According to a study published in the journal Clinical Cancer Research, a serum test to detect mammaglobin, a protein secreted by breast cancer cells, offers promise as a screening tool. The test may also improve monitoring of treatment response and recurrence.
An important focus for many cancer researchers is identifying biologic markers of cancer that can be easily detected in serum. Such markers are used for cancer screening and can improve treatment follow-up. An example of such a marker is prostate-specific antigen (PSA), which is used to screen for prostate cancer and to monitor prostate cancer patients after treatment. Although the accuracy of the PSA test is far from perfect and thus somewhat controversial, it is widely used. There have been no comparable serologic markers for breast cancer.
Researchers at Washington University in St. Louis have recently identified and tested a potential serologic marker for breast cancer. The protein, called mammaglobin, is produced by breast tissue. Serum levels of mammoglobin may distinguish women with and without breast cancer.
To evaluate whether mammaglobin testing accurately identifies women with and without breast cancer, the researchers assessed mammaglobin expression in various types of tumor tissue, as well as the level of mammoglobin in the serum of women with and without breast cancer. Tumor tissue from patients with cancer of the breast, prostate, colon, lung, uterus, or ovary was evaluated. Serum testing was conducted in 26 women with metastatic breast cancer and 56 women without breast cancer (all had a negative mammogram and no history of breast cancer or other breast disease).
Analysis of the tumor tissue found that 72% of the breast tumor tissue tested positive for mammaglobin, whereas none of the prostate, colon, lung, or ovary tissue tested positive. One of 31 uterine tumors tested positive for mammaglobin, but the researchers note that it’s possible that this tumor came from a woman with undetected breast cancer.
Analysis of the serum samples also found that mammaglobin levels could distinguish between women with and without breast cancer. Level of mammaglobin was significantly higher among women with metastatic breast cancer than among women without breast cancer. Level of mammaglobin did not vary by age, race, hormone therapy, estrogen/progesterone receptor status, or HER-2/neu.
The researchers conclude, “…this serum marker holds significant promise in improving the survival potential of breast cancer patients through early detection and/or more accurate monitoring of response to therapy and relapse.”
Reference: Bernstein JL, Godbold JH, Raptis G et al. Identification of Mammaglobin as a Novel Serum Marker for Breast Cancer. Clinical Cancer Research. 2005;11:6528-35.
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