micrometastasis

noun

mi·​cro·​me·​tas·​ta·​sis ˌmī-krō-mə-ˈtas-tə-səs 

plural micrometastases -ˌsēz 

: the spread of cancer cells from a primary site and the formation of microscopic tumors at secondary sites

also : one of those microscopic tumors resulting from micrometastasis

micrometastatic

-ˌmet-ə-ˈstat-ik 

adjective

micrometastatic disease