So how does lymphedema start? The current thinking is that, in some people, the lymph finds other ways to get where it needs to go after the lymphatic system is disrupted by breast cancer treatments. We’re not sure how this happens, but the body finds a way to compensate. The system adapts to the change.
In other people, the remaining lymph nodes and vessels can’t keep up with the tissues’ need to get rid of extra fluid, proteins, and waste. With fewer lymph nodes, too, the proteins and wastes do not get filtered out of the lymph as efficiently as they once did. Very gradually, waste and fluid build up in the tissues of the arm, hand, breast, chest, or trunk. One or more of these areas may be affected. The result is typically mild lymphedema, which can get worse if it’s not treated. At first, you might notice that your arm or chest feels a little bit different — tingly, uncomfortable, achy, or “full”— or that your bra, sleeve, watch, or ring feels a little tight.
In people who develop lymphedema, symptoms typically appear within 3 years after surgery, although many cases appear 3-5 years after treatment. We don’t have enough longer-term studies to say for sure what the risk is after 5 years. However, there have been cases of lymphedema developing many years or even decades after treatment.
First symptoms are sometimes triggered by a specific event, such as overuse of or injury to the arm. If your lymphatic system is already having a hard time keeping up, such events can “tip” the body into lymphedema. For instance:
- Suppose you normally cook for two people but suddenly spend a holiday cooking for 20, or you tackle hours of intense yard work on a hot day. These activities send more blood pumping through your arm than usual. More blood means more fluid in the tissues, which also means more lymph entering the lymphatic system.
- Let’s say that you get a cut, even a very small one, that allows bacteria to get into the hand or arm. The lymph drains to the underarm lymph nodes that are responsible for straining out the bacteria and setting your body’s immune system into action. But fewer nodes are now available to do this work, so the immune response is slower. The bacteria have the chance to start multiplying in the lymph fluid — a perfect environment because it’s filled with nutrients they can thrive on. The cut gets infected and the lymphatic system is even more overwhelmed. The lymph has so much debris in it that it starts to clog the system. The fluid can’t get where it needs to go and starts pooling in the tissue.
Kathryn Schmitz, PhD, MPH, professor in the division of clinical epidemiology at the University of Pennsylvania, offers this analogy: “If you’ve ever lived at the bottom of a hill, you’ve seen what happens to the storm drain during a rainstorm. Sticks, leaves, and other debris come out of the trees and they all move toward the drain. All of this stuff is trying to get into the system and it gets stuck. The street starts to flood not just with plain old water, but with junk-filled, dirty water. That’s a good way to understand the beginning stage of lymphedema.”