Medical Genetics For the most part, cancer arises from a single cell, that is, cancer is a clonal disease. The average human being contains about 1014 cells(i.e 100000,000,000,000 cells), any one of which could in principle, become a cancer cell, if it acquired the right sort of mutations while it still had the potential to proliferate.Medical Genetics For the most part, cancer arises from a single cell, that is, cancer is a clonal disease. The average human being contains about 1014 cells (i.e., 100,000,000,000,000 cells), any one of which could, in principle, become a cancer cell, if it acquired the right sort of mutations while it still had the potential to proliferate