Is LE a symptom of breast cancer or result of treatment?

I don't think so. Lymphedema is a direct result of removing the lymphnodes during surgery...

There are two categories of lymphedema: primary and secondary. Primary lymphedema is something that a person is predisposed to from birth, though it doesn't necessarily show up at birth. The three categories of primary lymphedema show up at different ages: birth, adolescent, and 20s-40s. Secondary lymphedema is caused by something specific. Worldwide, the most common cause of secondary lymphedema is an infection called filariasis. In the western world, the most common cause of secondary lymphedema is cancer treatment. Is it possible for lymphedema that shows up in the absence of diagnosed breast cancer to be a symptom of it? Yes, it is an outside possibility, but in someone without known cancer who develops lymphedema, it is far more likely that it is either primary lymphedema or filarial lymphedema (if at risk).

The other thing I would point out is that examining your breasts is a learned art. You said in your other thread that the lumps were symmetrical and extremely large, but the doctor examined you and did not find any masses. Is it possible that you were feeling your ribs? I am a doctor and often have younger patients who come in after finding a rib. I use it as an opportunity to educate, but honestly, I'm just really glad that they are starting to do regular self-exams.

DocSR: The classification of lymphedema as being primary VS secondary has become very inexact as we learn more about lymphedema. Susceptibility to lymphedema given a precipitating trauma is being found to be somewhat genetically determined,possibly related to robustness of the genetically-determined lymphatic system development. Susceptibility may be related to an intrinsic lymph transport margin. The distinction of primary VS secondary lymphedema is becoming less and less clinically relevant.