The process of cutting apart or separating tissue as, for example, in the study of anatomy or in the course of a surgical procedure. In talking about breast cancer, this word is most often used when talking about removal of lymph nodes from under the arm, or armpit, or “axilla”. We use the term “axillary dissection” to describe the removal of the fatty tissue here. When lymph nodes are to be removed, it’s not like picking grapes out of jello, it’s more like scooping out all the jello (fatty tissue) that contains the grapes (lymph nodes), and then later the pathologist will carefully go through the tissue to find all the lymph contained there. For this reason, there is no set number of lymph nodes that will be removed, since it depends on several factors. The number may range from 5 up to 40, and sometimes more or less than this as well.

A passage or a tube with well-defined walls suitable for the conveyance of air or liquids, as the bile duct and the pancreatic duct. In the breast, this of course is the passage way for milk when it is produced in the lobules, and this is the site where the most common type of breast cancer arises.

A precancerous condition characterized by the clonal proliferation of malignant-looking cells in the lining of a breast duct, without evidence of spread outside the duct membrane to other tissues in the breast or outside the breast. DCIS is clearly the precursor (forerunner) of invasive breast cancer. This is evident from the sharing of clonal chromosome changes by DCIS and adjacent invasive cancers. In other words, invasive breast cancer evolves from DCIS. Also called intraductal carcinoma.
A simple analogy to understand DCIS is to think of it as “cancer seeds.” Just as a dandelion seed has the ability to take root, sprout, and spread in your lawn, so can DCIS take root, and “invade” into the surrounding tissue. As a seed, it hasn’t done yet what cancers do, that is, to invade into tissue, but we know it has all the potential to do so if left in place.