Cancer may be viewed as a collapse of equilibrium in a cellular ecology, where one subpopulation of atypical cells grows abnormally to the detriment of the others and drives the system to premature death. We present an abstract agent-based model of a cellular ecology comprising two distinct cell types that are interconnected in a way that allows a sustainable population equilibrium. We show that some kinds of genetically controlled mutations may cause cancer and how accumulation of deleterious mutations in atypical cells may lead to aggressive cancer. We also show the effects of treatment with a toxic nutrient which affects atypical cells more than typical ones. In that case, we show that cancer may be constrained or healed depending on the toxicity of the nutrient, the age of cancer attack, the time elapsed before cancer identification and the duration of the treatment. These results are in accordance with the properties of real cancerous systems and thus our model may be extended to support further research on cancer development in cellular ecologies and means of fight against it. An additional Hayflick-like limit of reproduction is finally shown to lead to more robust cellular behavior and to resistance to accumulation of deleterious mutations.