1. This paper assumes angiogenic factors are a public good, meant to increase vasculature within tissues thus providing oxygen for cell function and survival.
  2. Def: Clonal Selection Theory [cancer results when natural selection sorts among genetically distinct clones within developing and established tumors, favoring those with malignant traits.
  3. This public good is assumed to be shared equally until "free-rider" clones (a concept derived from evolutionary game theory) arrive in the system and utilize the resources without contributing energy [in the form of ATP] to angiogenesis, and instead allocate resources towards proliferation.
  4. This focus on proliferation allows the cheating clones a selection advantage, which out-competes the advantage of their angiogenic counterparts.
  5. As cheater clones populate the tumor, cells grow further away from the oxygen source (as they are not secreting angiogenic factors) to which focal necrosis becomes inevitable.
  6. This necrosis harms the tumor, however this is irrelevant to the cheater as selection acts towards reproduction of the individual. 
  7. Inq: How common are mutations that lead to a focus on proliferation? Hyp: This should be quite common seeing as the driving force behind selection is reproduction, so mutated cells introduced to the system might not have a genotype that abides to the normal functioning for the system.