Natural history model of cancer: The volume of the primary tumor V(t) grows exponentially with tumor volume doubling time, TVDT, and the treatment cure threshold occurs at size VC. Patients detected and treated at or before VC are cured of their disease; otherwise, lethal metastatic burden B(t) will grow exponentially from VC in proportion (f) to the primary tumor and become the cause of cancer death at a maximal metastatic tolerance level BD. The lethal metastatic burden becomes observable when it reaches a fraction (k1) of BD . A patient detected after this moment is regarded as having advanced staged. A patient is detected from either the primary tumor or metastasis, dependent on which prompts detection present first. The primary tumor is detected at size VP, and the lethal metastatic burden is detected when it reaches a fraction (k2) of BD.