into the lymph nodes

before you can understand the importantance of cancer spread to the lymph nodes, you need to first understand the fuction of the lymphatic system. as the arteries enter tissues, they subdivide into progressively smaller branches. in the smallest vessels, called capillaries, oxygen and food are released into the tissues and carbon dioxide and other wastes are removed. in order to facilitate the transfer of these and other blood components, the capillaries are leaky. a wide variety of proteins and fluid constantly exit the capillaries and enter the tissues. without such an escape path, this fluid would accumulate in the tissues, causing edema.
fortunately, the lymphatic vessels are open-ended tubes that can drain this fluid out of the tissues and channel it back toward the heart. all of the lymph nodes from the lower extremities and pelvis merge into one large pipe in the back of the abdomen. this large pipe passes up through the middle of the chest, gathering fluid from the lungs and exiting into the venous blood behind the clavicle on the left.
if this were the complete story, any parasite or bacteria that entered your tissues through a wound would rapidly gain access to your blood, which has potentially devasting consequences. to avoid such a scenario, the body has established a rather sophisticated defense system. first, various white blood cells involved in killing invaders also constantly exit the capillaries and enter the tissues of the body, thereby placing them in position to handle bacteria and parasites. these same white cells enter the lymph channels and could travel upward with any invading bacteria, virus or parasite. and the lymphatic channels pass through four or five lymph nodes on their way to the blood stream. each lymph node acts like a filtering device, capturing invading organisms. once trapped in the node, an elaborate process takes place that aims to kill the invading organism. I am sure you seen this in action. if you get an infection in your throat, the lymph nodes in your neck enlarge as they fight the infection. likewise, if you have a boil on your legs, the nodes in your groin enlarge and become tender.
once in the pelvic lymph nodes, the natural path of cancer spread is up the lymphatic chain into the abdomen, chest, and then on to the venous blood behind the left clavicle. there is a node right next to the point where the lymphatic channel empties into the veins behind the left clavicle. this lymph node is called virchow’s node, named after one of the major german pathologists of the 1800’s, rudolph virchow. once the cancer cells enter the arterial blood supply, they travel to all parts of the body.