Over 35 years, data and knowledge have internationally evolved from biochemical, biomedical and clinical research on vitamin Q₁₀ (coenzyme Q₁₀; CoQ₁₀) and cancer, which led in 1993 to overt complete regression of the tumors in two cases of breast cancer. Continuing this research, three additional breast cancer patients also underwent a conventional protocol of which included a daily oral dosage of 390 mg of vitamin Q₁₀ (Bio-Quinone of Pharma Nord) during the complete trials over 3-5 years. The numerous metastases in the liver of a 44-year-old patient “disappeared,” and no signs of metastases were found elsewhere. A 49-year-old patient, on a dosage of 390 mg of vitamin Q₁₀, revealed no signs of tumor in the pleural cavity after six months, and her condition was excellent. A 75-year-old patient with carcinoma in one breast, after lumpectomy and 390 mg of CoQ₁₀, showed no cancer in the tumor bed or metastases. Control blood levels of CoQ₁₀ of 0.83-0.97 and of 0.62 μg/ml increased to 3.34-3.64 and to 3.77 μg/ml, respectively, on with CoQ₁₀ for patients A-MRH and EEL.