Been almost six years since sweating started. How r tumors detected? Blood tests?

Sweating. Sweating is caused by many things. It's impossible to say what you have without knowing more information. You need to find the cause. The first thing is always blood tests. Once blood tests confirm an abnormality, imaging studies may then be done. We do not recommend imaging studies without knowing what we are looking for. See your doc for a frank conversation.
Depends on tumor. History, exam, blood tests, ct scan or mri.