In the late 1990s, observational studies showed that individuals with breast cancer, cancer of the pancreas, and lung cancer had lower plasma CoQ10 concentrations than healthy control individuals did. However, there have not been many clinical studies of Coenzyme Q10 as a therapeutic agent for the prevention or treatment of cancer.
In the ANICA breast cancer trial, Coenzyme Q10, as the primary agent in an antioxidant cocktail, showed promise as a treatment option. In an end-stage cancer trial, Coenzyme Q10 in combination with other antioxidants increased the survival period for 76% of the study participants. In other clinical studies, though, Coenzyme Q10 administration was not associated with reduced fatigue or with better quality of life in breast cancer patients and chemotherapy patients. More clinical research is needed.