Does coenzyme q10 reduce the risk of any cancers? if so, which ones?

Not to my knowledge: In fact, the whole history of supplements -- even antioxidants and omega 3's -- preventing cancer, prolonging life, or improving it quality is almost without exception, over the past forty years, a history of tremendous disappointment. You won't hear about this if you get all your information from "health" internet sites. If you're interested in this, get with an evidence-based holistic doctor.