An improved criterion for the evaluation of estrogen receptor binding data in human breast cancer.

The evaluation of the data is an important step in performing the estrogen receptor test. For this reason an effort has been made to derive a more reliable threshold criteria. Among the parameters considered, Xo, Ka, and BI%, only the former 2 appear to be suitable to allow a proper evaluation of the results. From the analysis of different types of carcinomatous or normal breast specimens, limit values of these parameters have been recovered for positivity and negativity of the estrogen receptor test. We found all the samples showing Ka less than 1.5 x 10(9) M-1 or Xo less than 5 fmol/mg proteins to be negative, those characterized by low values of both the parameters were borderline, and all the remaining ones were positive.