Hmm. My terrific lymphoedema therapist notes that officially there isn't a connection between a seroma and lymphoedema but as she puts it, it's hard to let the water out when the plug is still in the sink! I get my arm massaged every 4/5 weeks to keep my fluid levels down and my lymphatic system moving. It does cost a bit, but partly covered by my health insurance. Aspirations were never painful but rarely had any long lasting benefit - I "refilled" in days. So I am not sure what caused what. As you say, if you have general unwell symptoms it's hard to know when you have had multiple treatments. I never had any problem with herceptin, and while I do have some letrozole side effects, they are very specific. My oncologist had no qualms about draining, he didn't like the idea of chemo affected fluid hanging around. Different medicos, different approaches. I would certainly think it's worth seeing if your hospital has a lymphoedema therapist, rather than a general physio, or if you can be referred to one and what it may cost. Bottom line is how much trouble the seroma is causing? My first aspiration removed 1.5 litres - I was staggered but it explained why my mastectomy had left me quite rounded!!