  In sum, there appear to remain several open questions about the nature of cancer stem cells, and more generally, how to best intervene upon cancer to successfully eradicate the disease. According to the model of the disease inherited from the latter third of the 20th Century, somatic mutations, acquired over a lifetime, to the acquisition of cancer’s “hallmarks.” So, the best strategy for intervention may be targeting specific pathways associated with these hallmarks. In contrast, according to the Tissue Organization Field Theory (TOFT), changes in tissue organization yield carcinogenesis. Thus, the best strategy for intervention might be finding ways to intervene in the tissue microenvironment, so as to create an environment less hospitable to the growth of cancer cells. According to the cancer stem cell theory, cancer arises in cells that have distinctive properties: continuous renewal, and indefinite growth, permitting the emergence of new disease. On this view, eradicating these stem cells seems essential to cancer treatment. Philosophical work on cancer causation and explanation can better illuminate the competing presuppositions of different approaches, clarify their commitments, and offer insights into fruitful integration of new data. It is already clear that philosophical discussions of ambiguities in how we define and measure stemness is essential to understanding how best to prevent recurrence and treat the disease (Clevers 2016).