The search textbox has an autosuggest feature. When you enter three or more characters, a list of up to 10 suggestions will popup under the textbox. Use the arrow keys to move through the suggestions. To select a suggestion, hit the enter key. Using the escape key closes the listbox and puts you back at the textbox. The radio buttons allow you to toggle between having all search items start with or contain the text you entered in the search box.
A case in which cancer cells are found in the body, but the place where the cells first started growing (the origin or primary site) cannot be determined. Also called cancer of unknown primary origin and carcinoma of unknown primary.