%0 Journal Article
%T Cancer dynamics for identical twin brothers
%A Ali Ghaffari
%A Mostafa Khazaee
%J Theoretical Biology and Medical Modelling
%D 2012
%I BioMed Central
%R 10.1186/1742-4682-9-4
%X Some of the existing studies on cancer therapy are based on the assumption that cancer growth is a time invariant dynamic system [1]. They have been focused on the following objectives:(i) To reduce and control the tumor mass such that a specified volume is obtained at the end of the treatment [2].(ii) To lessen the treatment burden of patients. This method considers some constraints on the treatment policy [3].(iii) To evaluate the number of injected cells that affect the equilibrium points of the immune system and thus may ultimately be dangerous [4].Previous studies have investigated the effects of therapeutic inputs, which are considered to have direct effects on the system states [5]. However, the behavior of cancer changes as the disease progresses [6]. External stresses that represent destructive inputs, such as environmental and quality of life factors, can cause disability in the DNA repair genes [7]. They can also interfere with, and alter, the functions of regulatory growth signals (TGF-¦Á), growth-inhibiting signals (TGF-¦Â), and apoptosis (TP53) [6].We are interested in analyzing how inputs alter the dynamics of the human body, and whether this is the main factor involved in the occurrence of cancer. This paper deals with a comparison between the responses of human body cells in a set of twin identical brothers who live under two different conditions, or inputs. In the next section, a modified model for the human body cells is presented. In the third section, the equilibrium points of the system and its linear approximation are calculated. The fourth section investigates the stability analysis of the system, using stability theorems and trajectory patterns. The fifth and final section discusses the results and summarizes the conclusions.We have considered a set of identical twin brothers who were born with the same genetic structures. It is assumed that, after the birth, they reside and grow up in two different locations, and under different environmental
%U http://www.tbiomed.com/content/9/1/4