Anatomical bases for the radiological delineation of lymph node areas. Upper limbs, chest and abdomen

Cancer spreads locally through direct infiltration into soft tissues, or at distance by invading vascular structures, then migrating through the lymphatic or blood flow. Although cancer cells carried in the blood can end in virtually any corner of the body, lymphatic migration is usually stepwise, through successive nodal stops, which can temporarily delay further progression. In radiotherapy, irradiation of lymphatic paths relevant to the localisation of the primary has been common practice for decades. Similarly, excision of cancer is often completed by lymphatic dissection. Both in radiotherapy and in surgery, advanced knowledge of the lymphatic pathways relevant to any tumour location is an important information for treatment preparation and execution. This second part describes the lymphatics of the upper limb, of the thorax and of the upper abdomen. Providing anatomical bases for the radiological delineation of lymph nodes areas in the axilla, in the chest and in the abdomen, it also offers a simplified classification for labeling the mediastinal and intra-abdominal nodal levels, grouped in each location inside three major functional areas (called I, II and III) which are all divided into three sublevels (named a, b or c).