Are there cancers that could cause mild liver enlargement (16.7) without focal lesions? Also mild elevated ALT. Or would cancer always show focal?

Hepatomegaly. Hepatomegaly, or enlarged liver, is not usually a sign of liver cancer. There are many other things that can cause a large liver and an increase in the ALT. It is important to find the reason for the symptoms, to treat it before it becomes worse. You should see a gastroenterologist if you have not already. Good luck.