Entropy generation is a fundamental concept in the science of complex systems as well as in engineering applications. The entropy generation approach was developed to obtain the stationary states of these systems. In this paper, starting from these results, the entropy generation approach is presented as a powerful method useful to analyze molecular machines in relation to their role in living systems. Two examples on cancer are described: 1) the analysis of its evolution which suggests a new approach against it based on entropy generation and 2) the information obtained from the chemical interaction between anticancer drugs and microtubule