 The sentinel node procedure is the identification, removal and analysis of the sentinel lymph nodes of a particular tumour.The spread of some forms of cancer usually follows an orderly progression, spreading first to regional lymph nodes, then the next echelon of lymph nodes, and so on, since the flow of lymph is directional, meaning that some cancers spread in a predictable fashion from where the cancer started.In these cases, if the cancer spreads it will spread first to lymph nodes (lymph glands) close to the tumor before it spreads to other parts of the body.