The best way to determine if it is tumors or cystic lesions is to biopsy. There is no other way to tell. I wouldn't say that cystic lesions are out of the question, but tumors are more likely due to his age and the amount seen. Depending on the tumor diagnosis from biopsy, further information on what will work as far as radiation therapy and/or chemotherapy will be more evident. Medication is a very broad term. Chemotherapy drugs are considered medications. As far as non-chemotherapy medicines, anti-inflammatories, such as steroids (prednisone) or non-steroidals (aspirin, Rimadyl, etc) are most effective at limiting tumor growth (affects blood vessel growth in tumors) or even shrinking them. They are only palliative therapy, though, to make them feel better and give them longer. Eventually the tumor will become resistant to the effects and start growing again. It could take a couple week, or it could be a few months. Difficult to predict. With that many tumors, surgery probably wouldn't be feasible. You would have to remove too much of the liver.