Reading about cancer is second-hand experience, i.e., it is gaining knowledge from someone else’s experience. Laboratory work is first-hand experience. i.e., the researcher gains knowledge from her own experience, not someone else’s. That’s what the experimental method in science is all about: gaining knowledge through controlled experience. It is not the same kind of first-hand experience as undergoing the disease, but it is first-hand experience nonetheless. That’s why it’s called primary research. An experienced researcher might very well know more about cancer than the patient, though the researcher does not know what the patient knows, or does not know it in the same way.
Yes, it might cause confusion for the researcher to say “I’m dealing with cancer” if the context doesn’t make clear what she is talking about, so I probably shouldn’t have put it that way. But the researcher can still honestly say that her knowledge of cancer is based on relevant experience.
I think the phrase lived experience has become a kind boilerplate in certain kinds of discourse, but I’m not going to get into that (Google it if you’re interested).