In the future, biomarkers may be used as early markers of cancer and to predict a patient's response to therapy and overall chance of survival. A study published in the Journal of the National Cancer Institute address methodologic issues that surface when studying biomarkers.

The concentration of biomarker antibodies, antibodies against proteins that scientists use to measure the progression of a disease, can affect what a certain level of protein expression indicates about patient survival.

David L. Rimm, M.D., Ph.D., a member of Yale Cancer Center at Yale University School of Medicine and colleagues used tissue microarray analysis and a range of antibody concentrations to test the expression of HER2, p53, and the estrogen receptor (ER) proteins in tissue samples from tumors from 250 breast cancer patients.

When the authors used a high concentration of antibodies and an optimal range of data, low expression of HER2 and p53 proteins was associated with low patient survival. Alternately, when researchers used a low concentration of antibodies and an optimal range of data, high expression of HER2 and p53 proteins was associated with low patient survival. Rimm and colleagues suggest that biomarker antibody concentration appears to affect the relationship between biomarker expression and outcome in analyses measuring expression by use of a method used for quantitative analysis of protein expression, called AQUA.

In an accompanying editorial, Donald Earl Henson, M.D., of the George Washington University Cancer Institute in Washington, D.C., writes that the results from Rimm and colleagues "warrant consideration." He suggests that additional studies are required that use alternate antibodies, detection methods, and biomarkers.

SOURCE:
Journal of the National Cancer Institute, December 21, 2005