In the human, coenzyme Q10 (vitamin Q10) is biosynthesized from tyrosine through a cascade of eight aromatic precursors. These precursors indispensably require eight vitamins, which are tetrahydrobiopterin, vitamins B6, C, B2, B12, folic acid, niacin, and pantothenic acid as their coenzymes. Three of these eight vitamins (the coenzyme B6, and the coenzymes niacin and folic acid) are indispensable in the biosynthesis of the four bases (thymidine, guanine, adenine, and cytosine) of DNA. One or more of the three vitamins required for DNA are known to cause abnormal pairing of the four bases, which can then result in mutations and the diversity of cancer. The coenzyme B6, required for the conversion of tyrosine to p-hydroxybenzoic acid, is the first coenzyme required in the cascade of precursors. A deficiency of the coenzyme B6 can cause dysfunctions, prior to the formation of vitamin Q10, to DNA. Former data on blood levels of Q10 and new data herein on blood levels of B6, measured as EDTA, in cancer patients established deficiencies of Q10 and B6 in cancer. This complete biochemistry relating to biosyntheses of Q10 and the DNA bases is a rationale for the therapy of cancer with Q10 and other entities in this biochemistry.