Quantitation of autocrine regulation of tumor growth: a general phenomenological model.

We present a model that considers autocrine regulation of tumor growth as a feedback control system. The model is general in that it can accommodate any growth curve which fits the data. We propose an algorithm for quantitation of the open loop gain parameter and we define the autocrine gain parameter; these parameters express the efficiency of the feedback mechanism. The model provides guidelines for design of experiments to measure the contribution of autocrine regulation to growth of biological systems, particularly tumors.