A recent study published in the Journal of the National Cancer Institute suggests that measurements of hormone receptors in breast tumors with newer immunohistochemical assays predict patients' response to treatment as well as or better than measurements using older extraction assays.

Hormone receptors are used to select the type of treatment patients receive for early-stage breast cancer. In the past, extraction assays were the primary test for these receptors, but now immunohistochemical assays are used because they are less labor intensive and less expensive. However, researchers did not know whether using the newer assay to determine hormone receptor status could change trial results that had relied on older assays.

Meredith M. Regan, Sc.D., of the Dana-Farber Cancer Institute in Boston, and colleagues used an immunohistochemical assay to re-measure the hormone receptor levels in the tumor tissue of 571 premenopausal and 976 postmenopausal breast cancer patients whose levels had been measured in previous trials using the older assay.

For estrogen receptor measurements, they found that the immunohistochemical assays predicted disease-free survival times similar to traditional extraction assays. However, for progesterone receptor measurements, the immunohistochemical assay more accurately predicted patient response to treatment.

SOURCE:
Journal of the National Cancer Institute, November 1, 2006