3. Is lymphedema connected in any way to mets from breast cancer?
I wish I could ask you to clarify your question further. Are you asking :
A. Do metastasis from breast cancer cause lymphedema?
B. Does lymphedema cause or contribute to breast cancer metastasis ?
C. Do similar mechanisms acting on the lymphatic system contribute to lymphedema and / or metastatic disease in a person with breast cancer?
First, breast cancer metastasis can cause or contribute to lymphedema through obstruction of lymphatic vessels. Likewise metastatic tumors can compress the lymphatic vessels impeding drainage andbackflow then leads to lymphedema.
Recent scientific investigation reveals to us there are a number of tumor-associated biologic mechanisms that control of growth of lymphatic vessels ( lymphangiogenesis).Since most cancer metastatic cells travel by lymphatic vessels , this clarifies one concept of tumor lymphangiogenesis actively promoting metastasis.
Scientists have looked into the molecular mechanisms acting when lymphatics are dysfunctional such as in lymphedema.Some of the molecular mechanisms they have seen participate in pathways of signaling. These pathways of signaling may send out growth messages while some of the signals "speak" to the walls or lining of lymphatic vesselscommunicating transportation information of particles ( cells) in or out of the lymphatic vessels.
When you take into consideration that cancer tumors are talking,lymphatic vessels are talking and dysfunctional lymphatic vessels, like in lymphedema, are talking it is conceptually easy to see that lymphedema can be related in "some way i.e. any way" to mets from breast cancer.
At present the full extent to which this is true and all the practical implications are unclear or just being discovered. Primarily cancer scientists are interested in the "discussions" between cancer tumors and lymphatic vessels.By understanding these molecular discussions , prevention of cancer spread and development oftreatments are possible.