This paper deals with the modeling of the early stage of cancer phenomena, namely mutations, onset, progression of cancer cells, and<br />their competition with the immune system. The mathematical approach is based on the kinetic theory of active particles developed to describe the dynamics of large systems of interacting cells, called active particles. Their microscopic state is modeled by a scalar variable which expresses the main biological function. The modeling focuses on an interpretation of the immune-hallmarks of cancer.Fil: Abdelghani, Bellouquid. Cadi Ayyad University; MarruecosFil: de Angelis, Elena. Politecnico Di Torino; ItaliaFil: Knopoff, Damián Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigación y Estudios de Matemática de Córdoba(p); Argentina