In order to understand why lymphatic drainage of the breast may occur, a basic comprehension of the lymphatic system is a good place to start. Also referred to as the lymphoid system, this component of the immune system functions to gather clear fluid called lymph toward the heart. It is somewhat of a filter for the body and acts to protect against foreign bodies, including infection. For this reason, excessive lymphatic drainage of the breast could be linked to an infection in this area.
Regardless of the presence of infection, there is always lymphatic drainage of the breast. After lymph accumulates, it returns to the heart by reaching a great vein through a lymphatic duct. The pattern of fluid movement is a cycle. Blood leaves the heart and reaches the organs as interstitial fluid, the rest of which returns to the heart as normal, and then the interstitial fluid moves into the lymphatic system. Once the lymphatic system has absorbed this fluid through lymph capillaries, it moves to lymph vessels, eventually reaching the right or left thoracic duct. These ducts then drain into a major vein, where the fluid can join the blood flow back to the heart.
The lymphatic system has many functions, some of which are undesirable. The positive functions of the lymph system are to remove interstitial fluid, absorb and transport fatty acids, and transport other immune-related cells, such as white blood cells. The transport of bodily substances by the lymphatic system does not always have a positive impact. One way in which lymphatic drainage of the breast can be dangerous is when it transports cancer cells. These malignant cells may spread throughout the body by the lymphatic system through a process known as metastasis. For this reason, attending physicians often focus on the lymphatic systems of those suspected to suffer from cancer.
The proximity of this system to the tissues of the body that can foster cancer cells contributes to the ease with which these dangerous cells can spread. This is why the lymphatic system and its associate drainage are used to help diagnose and treat different types of cancer. When lymph nodes, another feature of the lymphoid system, become swollen, a person should immediately contact a medical professional. Although this is usually indicative of a simple infection, there is always the chance of a more serious and chronic condition.