@jchantler I think @val64 can answer this question better than me.

My husband is a pathologist, now retired. He refers to these cancers that we are discussing as "tumors". Like me, you probably think of tumors as a solid sort of lump. I read that a tumor refers to a mass of abnormal cells.

Here is information from Cleveland Clinic:

What is a tumor?

-- https://my.clevelandclinic.org/health/diseases/21881-tumor

Does this help?