I have blood in my semen wgy I am 30 years old do I have some kind of cancer

Clearly . Clearly you are worried, there are a number of possible reasons that there may be blood in your semen. You need to see your doctor so that he or she can examine you and find the etiology. The doctor will also obtain information from you to help make the correct diagnosis. I would not jump to the conclusion that you have cancer but i would get it checked out.