T or F? Not all LCIS becomes ILC but all ILC was once LCIS

I would assume so..............the difference being that the LCIS has spread beyond the original site to become invasive?

I too assume so, @cindylb

LCIS is not invasive and Lobular Carcinoma would be called, invasive. In LCIS the cancer cells are contained and when they leave their 'little home'...they are invasive and have the potential to spread to other parts of the breast and beyond. LCIS may not be become invasive or spread....or it could. Removing LCIS reduces the chance of it becoming invasive because it's removed. However, you can get LCIS again, in a new location and it could spread (that is what happened to me). The LCIS I had in my left breast was removed and never grew back or again. However, I developed invasive lobular cancer in the other breast, the right, and then I had evidence of cancer growth in both breasts and had a bi lateral mastectomy because I had cancer in both and assumed it could happen again. It might not have in the case of some people, but the extensive testing that is done on breast tissue, following mastectomy showed more LCIS in my right breast and DSIC (ductal) in both breasts as well as other abnormalities that might be troublesome at some point. Of course you don't have that info unless they have all your breast tissue to test. If I hadn't removed the LCIS in the left breast it might have stayed LCIS or become invasive. We will never know.

LCIS has not metastasized and is contained in it's original location in the breast. ILC has invaded the surrounding tissue and has higher incidence of metastasis.